The goal of cancer screening is to detect asymptomatic cancers by using diagnostic tests or methods which can be proposed to a great number of healthy persons. The result of these tests enable the separation of healthy subjects with no cancer from persons who may be affected by cancer and for whom further thorough examinations are needed.
The validity of a screening policy can be demonstrated by the reduction of mortality (and reduced treatment morbidity) in patients who have been screened compared to patients for whom cancer has been diagnosed after the apparition of classical symptoms.
Ideal cancers for screening should :
Every screening technique should be evaluated for its postive and negative effects.
The benefits include :
Negative aspects
The negative aspects should not be neglected: in fact, we are dealing with a healthy population presenting no symptoms and with no particular demand. They include:
In summary, potential drawbacks should be minimal in relation to genuinely observed advantages.
1) Sensitivity and specificity:
Cancers which can been screened
In order for valid screening to be possible, the pre-clinical phase of the cancer involved should be long enough to enable screening to be carried out within this period. The advance in diagnosis offered by such screening should then give way to active therapy, reducing, if possible, mutilations and other therapeutic complications involved in the treatment of more advanced cancer.
If the pre-clinical phase is too short (which is currently, but may not always be, the case for lung cancer and leukaemia), then screening is impossible.
If no efficient treatment exists (within current cancer discovery conditions) or if cancer has already produced metastases (for instance - for many brain tumours such as glioblastomas or pancreas carcinoma with liver metastases), screening has no utility.
We need, of course, to have a simple, reproducible and relatively inexpensive test: systematic pulmonary radiography does not permit secure early diagnosis of lung cancer (too many false negatives); nowadays an annual multi-slice helicoidal scanner for all smokers is economically too expensive even if some studies have shown its potential utility .
For every screening test, we can define the following values : true positive (TP), true negative (TN), false positive(FP), false negative(FN), positive predictive value (PPV) and negative predictive value (NPV).
A good screening test should be very sensitive (it do not miss cancers) and specific (fear of cancer inducing unnecessary further examinations)
Generally speaking, the more sensitive a test is, the less specific it is (other pathologies can also induce abnormal tests: for instance PSA can also be increased in prostatitis and faecal blood can be observed during colon inflammatory diseases.
On the contrary, the more specific a test is, the less sensitive it is (many cancer patients do not have a positive result: for instance, normal pulmonary radiography for small lung cancers andabsence of elevation of the carcino-embryonic antigen (CEA) in small colon carcinoma.
A low positive predictive value will induce, in order to confirm the diagnosis, high numbers of painful, costly and unnecessary examinations to healthy persons: for instance prostate biopsies for an elevated prostatic specific antigen ( PSA) level.
A low negative predictive value will mistakenly reassure people who have cancer: for instance, the absence of faecal blood associated with the presence of a colon cancer which intermittently bleeds.
What proves the efficiency of a screening policy is the diminution of mortality
The diagram below does not show any advantage in earlier screening since the mortality is identical between a population submitted to a screening policy and a population where no such policy has been instituted.
Screening is of real interest if it brings longer survival for the whole population with a clear decrease in the mortality of the screened cancer. This is the classical scenario where, generally, small cancers are more often cured using simpler treatment modalities. As a matter of fact, the increasing number of small cancers in the screened population will bring a much higher survival curve than in the non screened population.
The diagram below attempts to explain how such interval cancers occur. Let us suppose that the cancer can be clinically discovered when its diameter is around 18 mm (blue horizontal line).
If the campaign screens the population every two years (red numbers), the screening test will reveal the cancer between test T2 and test T3 (i.e. a tumour which has just attained a diameter of 18 mm).
If the campaign screens the population every three years (blue numbers), the T2 test might easily fail to spot the tumour which measures only 15 mm in diameter, and it will only be discovered at T3 (i.e. when the cancer is already larger than 2 cm in diameter).
It is almost impossible to totally avoid the occurrence of interval cancers:
In the 70 - 74 year age bracket, the incidence of breast cancer is high, but data concerning the value of mass screening is scarce. Taking into account the organisational difficulties involved in large scale campaigns, the extension of screening to this age bracket appears to be currently premature in France. On the other hand, it appears logical to continue screening between 70 and 74 years for women already included in the systematic screening program from the age of 50 to 69.
For the 40-49 year age bracket, the benefit of systematic screening is low and is only proven for studies with at least ten years follow-up with regular mammographies carried out in optimal conditions. Screening risks are not insignificant, particularly the risk of false positives which are followed by numerous other examinations (up to biopsies), bringing a lot of unnecessary anxiety and psychological traumatism.
The European reference for participation level after three years should be at least 60% (in France, it is around 65% if we include the mammographies carried out outside campaigns for benign breast pathologies).
The recall level (suspect images needing further exploration) should not be higher than 7%: a higher level would mean a great quantity of false positives and a much lower rate would suggest a high number of false negatives (poor radiological interpretation).
The biopsy rate (i.e. to verify dubious radiological images) should be lower than 1.5%, otherwise mammography interpretation should be improved by radiologist training. In France this rate is approximately 1%.
Taking into account epidemiological data in Europe, the detection rate (cancer / women tested) should be around 5% . In France the mean rate is 5.9%.
The percentage of invasive cancers without node involvement (i.e. small cancers of good prognosis) should be higher than 60% (in France, it is around 69%). At least 30% of the discovered cancers should have a diameter of less than 1 cm (in France: 36%).
Therefore, similarly to many other countries, breast screening in France is a question of political commitment: the recent French 'plan cancer' has established the goal that every woman in our country should have access, in the next two years, to efficient breast cancer screening. We should see a genuine decrease in the mortality of breast cancer in the next few years.
The screening of Cervix Uteri cancer should theoretically be the most efficient cancer screening since it can detect pre-cancerous lesions and avoid the development of cancer. Once the cancerisation process is engaged, it can detect in situ cancers (i.e. for which 100% of patients can be cured). Even with more advanced disease (T1 and proximal T2), curing probability remains high.
This recommendation is simple but its application proves to be difficult due to:
One of the major advantages of the pap smear is the possibility of discovering and treating pre-cancerous lesions (dysplasia also called intra-epithelial neoplasia).
In every country where systematic screening campaigns have been organised (like in the United Kingdom or in Iceland), the mortality rate by cervix uteri carcinoma sharply diminishes
Unfortunately, in France, like in many other countries, such campaigns are not organised. Quoting cultural differences between Anglo-Saxon and Mediterranean countries is a false argument for not applying such a policy: in the department of Doubs (in Eastern France), a clear local political commitment and many volunteers have led to a significant decrease in the mortality rate by this cancer.
Clear financing of the campaign should also be made available in order to allow poor and disadvantaged women to benefit from the program.
Quality control is high for the cytologists (at least in France) and a clear interpretation description has been defined by Pathologist Societies.
A very simple lexicon may help to understand these cytological reports.
A simple attitude can be adopted according to results:
This scheme is inspired by the Canadian Health Ministry.
We have the means to almost make this cancer disappear: but it is not a very ‘chic’ cancer: many of its victims have neither the time, the knowledge, the means, nor the will to be screened. Only a clear political commitment could help solve this problem and offer the same great success as seen in certain Scandinavian countries.
From its well known evolution from a simple adenoma towards colic cancer through multiple steps separated by relatively long periods of time, colo-rectal cancer should constitute an ideal model for setting up a screening policy.
In fact, two methods are proposed:
However, compliance to the test has always been a problem. Healthy people find the stool collection procedure very unpleasant and are difficult to motivate. Moreover, physicians often lack confidence in this method given that around half of the negative test results could in fact be false negatives, since adenoma and even adenocarcinoma do not regularly bleed.
Systematic endoscopy, even at a less frequent rate (once every five years) is difficult to achieve due to the small number of gastro-enterologists, the examination cost and the discomfort it causes, which all prevent its regular repetition.
For patients having genetic or family predisposition to colo-rectal carcinoma, screening should be more rigorous and involve endoscopy.
It is therefore difficult to obtain a clear recommendation for colo-rectal cancer screening. Patients should be informed of the possibility of Haemoccult II, but a clear explanation of the test should be given (its value, its limits). In fact, among patients with a negative Haemoccult II test, colo-rectal cancer incidence is approximately half that of the normal population . It is only through clear dialogue and informed patient consent that both the general practitioner and the patient can be protected from false interpretations.
If the patient is particularly anxious about colon cancer and has objective reasons to fear the development of polyps, it might be safer for the physician to ask a gastro-entorologist for advice, and to propose a colonoscopy.
Prostate cancer is the second cause of death by cancer in men (after lung cancer) and it is the most frequent cancer. It is characterised by a local phase during which radical treatment may cure it (however this treatment can be aggressive), and a metastasis phase for which only palliative measures are feasible, without modifying the poor prognosis, even if they can slightly increase survival.
Since the introduction of the PSA test (around 1990), many men between 50 and 70 have been tested. In the United States, due to the very important statistical work of the Registries (SEER study from NCI), it is clear that prostate cancer is now diagnosed at an earlier age, with a more limited stage than in previous years, but we still do not have scientific data proving that survival in prostate cancer patients has been increased.
PSA can be elevated by prostate cancer but also by other prostate diseases (benign hyperplasia, prostatitis, recent cystoscopy). Classically, one gram of cancer gives a blood level of 3 ng/ml whereas one gram of normal prostate 0.3 ng/ml.
Certain questions need to be clarified before systematically proposing a PSA test to men over 50.
Are all cancers detected after a PSA test clinically important? We know that, at autopsy, many old men have prostate cancer which has never be clinically significant (unfortunately we do not know their pre-mortem PSA value!).
Should we apply a variation according to age? It has been suggested to consider, as an upper PSA limit: 2.5 ng/ml up to 50 years, 3.5 ng/ml up to 60 years, 4.5 ng/ml up to 70 years, and up to 6.5 ng/ml after 70 years.
Should we use the free PSA / total PSA fraction as a way to better differentiate patients requiring biopsy when the total PSA is not very high?
In fact, the real problem is knowing what to do with a localised prostate carcinoma. Many treatments are aggressive and past controversies between surgeons and radiotherapists have not improved the quality of the debate.
What should be proposed if the biopsy is positive?
Age at diagnosis should be treated with caution. Spontaneous survival according to age is well known. Low histological grade and associated pathologies may indicate watchful waiting or hormone therapy.
However, men who enjoy good health at 75 may live long enough to run the risk of developing metastases and die in pitiful conditions inciting a more aggressive approach to their cancer.
Our citizens want to be better informed. Before proposing the PSA test, it is necessary to clearly inform them of the consequences of a positive test.
The American Cancer Society recommends teaching male adolescents on how to self examine their testes. However the low incidence of this tumour renders a real screening policy difficult to set up.
A patient with many naevi or brown lesions should be advised of the importance of looking out for (or being regularly checked by a physician) any modifications in order to diagnose a melanoma as quickly as possible.
Some lesions, like Bowen's disease , are true in situ skin cancer on unexposed skin surfaces.
When treating elderly people, the physician should be aware that the so-called benign skin epithelioma may give rise to very aggressive tumours, and should be treated as early as possible.
Some parts of the body skin may also degenerate : prudish attitudes should not prevent a clinical examination of vulvar itching to diagnose vulvar carcinoma , likewise itching or haemorrhage for penis carcinoma .
The validity of a screening policy can be demonstrated by the reduction of mortality (and reduced treatment morbidity) in patients who have been screened compared to patients for whom cancer has been diagnosed after the apparition of classical symptoms.
Ideal cancers for screening should :
In reality, up to now, the only cancers which can be practically screened are : breast, cervix uteri, skin, colon and rectum, prostate, although controversy remains regarding certain techniques.
- · be frequent with heavy mortality,
- · remain over a long period at a pre-clinical stage (without symptoms),
- · be detected at a stage when therapy is efficient,
- · be detected using a high sensitivity and high specificity test, of a moderate cost and limiting inconvenience to the healthy person in order to be accepted and regularly repeated.
Every screening technique should be evaluated for its postive and negative effects.
The benefits include :
- · improved prognosis for patients for whom cancer has been detected through screening,
- ·reduction in aggressive treatment necessary to treat this screened cancer,
- · peace of mind for subjects with a negative test,
- · reduction of the general cost of cancer treatment,
- · and, of course, a reduction in mortality via the screening policy.
Negative aspects
The negative aspects should not be neglected: in fact, we are dealing with a healthy population presenting no symptoms and with no particular demand. They include:
- · discomfort brought by screening tests,
- · psychological and economical consequences of false positive results (more complex examinations which take place to finally reveal absence of pathology): precise description of morbidity (and sometimes mortality) induced for no reason,
- · the more tragic consequences of false negative.
In summary, potential drawbacks should be minimal in relation to genuinely observed advantages.
cancers:
1) Sensitivity and specificity
2) Delay effect
3) Interval cancers
4) Breast cancer
5) Cervix Uteri
6) Colon and rectum
7) Prostate
8) Other cancers
1) Sensitivity and specificity:
Cancers which can been screened
In order for valid screening to be possible, the pre-clinical phase of the cancer involved should be long enough to enable screening to be carried out within this period. The advance in diagnosis offered by such screening should then give way to active therapy, reducing, if possible, mutilations and other therapeutic complications involved in the treatment of more advanced cancer.
If the pre-clinical phase is too short (which is currently, but may not always be, the case for lung cancer and leukaemia), then screening is impossible.
If no efficient treatment exists (within current cancer discovery conditions) or if cancer has already produced metastases (for instance - for many brain tumours such as glioblastomas or pancreas carcinoma with liver metastases), screening has no utility.
We need, of course, to have a simple, reproducible and relatively inexpensive test: systematic pulmonary radiography does not permit secure early diagnosis of lung cancer (too many false negatives); nowadays an annual multi-slice helicoidal scanner for all smokers is economically too expensive even if some studies have shown its potential utility .
Screening tests
A screening test should be easy to perform and well accepted by healthy persons (especially if it needs to be repeated often), have only light secondary drawbacks and if possible cost as little as possible. But above all, it should be efficient.For every screening test, we can define the following values : true positive (TP), true negative (TN), false positive(FP), false negative(FN), positive predictive value (PPV) and negative predictive value (NPV).
| Cancer patients | Healthy persons | Total | Predictive value | |
| Positive test | True positive (TP) | False positive (FP) | Total positive (TtP) | PPV = TP/TtP |
| Negative test | False negative (FN) | True negative (TN) | Total negative (TtN) | VPN= VN/TtN |
| Total | Total cancer (TK) | Total healthy (TH) | - | - |
- | Sensitivity = TP / TK | Specificity = TN/TH | - | - |
A good screening test should be very sensitive (it do not miss cancers) and specific (fear of cancer inducing unnecessary further examinations)
Generally speaking, the more sensitive a test is, the less specific it is (other pathologies can also induce abnormal tests: for instance PSA can also be increased in prostatitis and faecal blood can be observed during colon inflammatory diseases.
On the contrary, the more specific a test is, the less sensitive it is (many cancer patients do not have a positive result: for instance, normal pulmonary radiography for small lung cancers andabsence of elevation of the carcino-embryonic antigen (CEA) in small colon carcinoma.
A low positive predictive value will induce, in order to confirm the diagnosis, high numbers of painful, costly and unnecessary examinations to healthy persons: for instance prostate biopsies for an elevated prostatic specific antigen ( PSA) level.
A low negative predictive value will mistakenly reassure people who have cancer: for instance, the absence of faecal blood associated with the presence of a colon cancer which intermittently bleeds.
2) Delay effect:
Delay effect and screening evaluation
Generally speaking, when patients have their cancer detected through a screening procedure, they survive longer than patients for whom diagnosis has been established after the appearance of symptoms. The diagram below shows that the time gained may be:- either a genuine benefit for the patient (for a long evolving cancer for which treatment at a precocious stage will be more efficient and will bring less morbidity): for instance, for cervix uteri carcinoma, early screening (in situ carcinoma) will induce local treatment which may not compromise the reproductive possibilities of the patient
- or solely an advance in diagnosis without any modification in therapy. For instance, treatment of leukaemia at the pre-leukaemic stage is not very different from treatment at the leukaemic stage and will always involve relatively high morbidity.
 |
The diagram below does not show any advantage in earlier screening since the mortality is identical between a population submitted to a screening policy and a population where no such policy has been instituted.
 |
Among the reasons for such equivalence,
- screening reveals cancer at stages that are just as advanced as those of fortuitous or symptom-related discoveries,
- the cancer spontaneously has a slow evolution and screening does not bring a real benefit,
- the screening technique may have noticeable drawbacks (!)
- the treatment involves heavy morbidity, regardless of the stage of the treated cancer (i.e. leukaemia).
Screening is of real interest if it brings longer survival for the whole population with a clear decrease in the mortality of the screened cancer. This is the classical scenario where, generally, small cancers are more often cured using simpler treatment modalities. As a matter of fact, the increasing number of small cancers in the screened population will bring a much higher survival curve than in the non screened population.
 |
For the cancer screened on the above diagram, screening is very efficient with smaller tumours benefiting from treatment. Survival is clearly increased both on median survival and on the number of surviving patients 5 or 10 years after treatment.
3) Interval cancers:
Interval cancers are cancers discovered between two screening campaigns.
If the campaign screens the population every two years (red numbers), the screening test will reveal the cancer between test T2 and test T3 (i.e. a tumour which has just attained a diameter of 18 mm).
If the campaign screens the population every three years (blue numbers), the T2 test might easily fail to spot the tumour which measures only 15 mm in diameter, and it will only be discovered at T3 (i.e. when the cancer is already larger than 2 cm in diameter).
 |
In well elaborated screening policy, these interval cancers should be of a small size: they reflect the degree of uncertainty of the intervals between screening campaigns, which are adjusted to the common speed of growth of the cancer (or the pre-cancer states) and to the cost and the discomfort of the tests proposed.
Independently of good policy, there will always be very aggressive cancers which do not follow the usual biology of their type of cancer or do not respond to usual therapies.
Unfortunately, these interval cancers may also be a sign of mistakes in the interpretation of screening tests: a highly secure reading of the test should be provided (for instance by double reading mammographies or pap smears).
4) Breast cancer Screening:
In France, in March 1999, a synthesis document was produced by the French Agency for Accreditation and Health Evaluation (ANAES) in order to answer very basic questions about breast cancer screening:
1. At what age does breast cancer screening bring a genuine scientifically proven improvement in the survival of breast cancer patients?The recommendations of this report are listed below:
2. What is the optimal interval before repeating a screening mammography?
3. How many radiological examinations should be carried out in order to optimise screening?
4. Are there women who should be excluded from screening programs?
Systematic screening is recommended between 50 and 69 years.
In the general population, the benefit of a breast cancer screening policy has clearly been demonstrated from the age of 50 to 69. Thus, in this age bracket, systematic screening should be set up.In the 70 - 74 year age bracket, the incidence of breast cancer is high, but data concerning the value of mass screening is scarce. Taking into account the organisational difficulties involved in large scale campaigns, the extension of screening to this age bracket appears to be currently premature in France. On the other hand, it appears logical to continue screening between 70 and 74 years for women already included in the systematic screening program from the age of 50 to 69.
For the 40-49 year age bracket, the benefit of systematic screening is low and is only proven for studies with at least ten years follow-up with regular mammographies carried out in optimal conditions. Screening risks are not insignificant, particularly the risk of false positives which are followed by numerous other examinations (up to biopsies), bringing a lot of unnecessary anxiety and psychological traumatism.
A mammography every two years
The interval between two screening mammographies must be lower than three years. When the interval is 3 years, there is an important number of interval cancers during the third year.Two views for each mammography
If some trials or programs in optimal situations have shown the efficiency of screening with only one mammographic view (mediolateral oblique), it has been clearly demonstrated that two views (mediolateral oblique and craniocaudal) are most cost-effective and reduce the risk of false negatives. Examination conditions should always be optimalWomen to be excluded from screening programs
Systematic screening programs are not recommended for women having had breast carcinoma, who should be followed-up according to other protocols. It is also not recommended for women with familial predisposition to breast cancer for whom more strict surveillance should be established.Quality control of screening programs
Screening campaigns are a very costly investment (around 50 € per screened woman) and directly financed by the State or local authorities. Therefore, resources and results are essential.The European reference for participation level after three years should be at least 60% (in France, it is around 65% if we include the mammographies carried out outside campaigns for benign breast pathologies).
The recall level (suspect images needing further exploration) should not be higher than 7%: a higher level would mean a great quantity of false positives and a much lower rate would suggest a high number of false negatives (poor radiological interpretation).
The biopsy rate (i.e. to verify dubious radiological images) should be lower than 1.5%, otherwise mammography interpretation should be improved by radiologist training. In France this rate is approximately 1%.
Taking into account epidemiological data in Europe, the detection rate (cancer / women tested) should be around 5% . In France the mean rate is 5.9%.
The percentage of invasive cancers without node involvement (i.e. small cancers of good prognosis) should be higher than 60% (in France, it is around 69%). At least 30% of the discovered cancers should have a diameter of less than 1 cm (in France: 36%).
Therefore, similarly to many other countries, breast screening in France is a question of political commitment: the recent French 'plan cancer' has established the goal that every woman in our country should have access, in the next two years, to efficient breast cancer screening. We should see a genuine decrease in the mortality of breast cancer in the next few years.
5) Cervix Uteri cancer screening:
Recommendation
Cervix Uteri cancer screening is based on the regular and systematic realisation of a cervico-vaginal smear every 3 years from the beginning of sexual activity up to the age of 65.This recommendation is simple but its application proves to be difficult due to:
Thus, a great number of women avoid this simple technique and unfortunately are treated for already invasive carcinoma when they present abnormal vaginal bleeding.
- lack of means,
- technical difficulties (in reality easy to solve),
- the psychological difficulties in accepting such screening, mainly among uneducated or marginal women.
One of the major advantages of the pap smear is the possibility of discovering and treating pre-cancerous lesions (dysplasia also called intra-epithelial neoplasia).
In every country where systematic screening campaigns have been organised (like in the United Kingdom or in Iceland), the mortality rate by cervix uteri carcinoma sharply diminishes
Unfortunately, in France, like in many other countries, such campaigns are not organised. Quoting cultural differences between Anglo-Saxon and Mediterranean countries is a false argument for not applying such a policy: in the department of Doubs (in Eastern France), a clear local political commitment and many volunteers have led to a significant decrease in the mortality rate by this cancer.
Clear financing of the campaign should also be made available in order to allow poor and disadvantaged women to benefit from the program.
Technical problems
The pap smear technique is simple: it needs to be learned by every general practitioner or cancer nurse. It is a painless procedure but is sometimes faced with strong prudish feelings (particularly for certain immigrants). A correct exposition of the cervix is necessary to obtain a good quality smear of the cervix junction.Quality control is high for the cytologists (at least in France) and a clear interpretation description has been defined by Pathologist Societies.
A very simple lexicon may help to understand these cytological reports.
A simple attitude can be adopted according to results:
 |
We have the means to almost make this cancer disappear: but it is not a very ‘chic’ cancer: many of its victims have neither the time, the knowledge, the means, nor the will to be screened. Only a clear political commitment could help solve this problem and offer the same great success as seen in certain Scandinavian countries.
6) Colon and rectum cancer screening:
From its well known evolution from a simple adenoma towards colic cancer through multiple steps separated by relatively long periods of time, colo-rectal cancer should constitute an ideal model for setting up a screening policy.
 |
The above diagram details the various molecular steps involved in colon carcinogenesis.
The problem for a good screening policy is to find an easy, reproducible test, well accepted by healthy individuals and not subject to too many false positive or false negative results.In fact, two methods are proposed:
- the systematic research of fæcal bleeding (with various modalities),
- systematic colonoscopy.
However, compliance to the test has always been a problem. Healthy people find the stool collection procedure very unpleasant and are difficult to motivate. Moreover, physicians often lack confidence in this method given that around half of the negative test results could in fact be false negatives, since adenoma and even adenocarcinoma do not regularly bleed.
Systematic endoscopy, even at a less frequent rate (once every five years) is difficult to achieve due to the small number of gastro-enterologists, the examination cost and the discomfort it causes, which all prevent its regular repetition.
For patients having genetic or family predisposition to colo-rectal carcinoma, screening should be more rigorous and involve endoscopy.
It is therefore difficult to obtain a clear recommendation for colo-rectal cancer screening. Patients should be informed of the possibility of Haemoccult II, but a clear explanation of the test should be given (its value, its limits). In fact, among patients with a negative Haemoccult II test, colo-rectal cancer incidence is approximately half that of the normal population . It is only through clear dialogue and informed patient consent that both the general practitioner and the patient can be protected from false interpretations.
If the patient is particularly anxious about colon cancer and has objective reasons to fear the development of polyps, it might be safer for the physician to ask a gastro-entorologist for advice, and to propose a colonoscopy.
7) Prostate cancer screening:
Since the introduction of the PSA test (around 1990), many men between 50 and 70 have been tested. In the United States, due to the very important statistical work of the Registries (SEER study from NCI), it is clear that prostate cancer is now diagnosed at an earlier age, with a more limited stage than in previous years, but we still do not have scientific data proving that survival in prostate cancer patients has been increased.
PSA can be elevated by prostate cancer but also by other prostate diseases (benign hyperplasia, prostatitis, recent cystoscopy). Classically, one gram of cancer gives a blood level of 3 ng/ml whereas one gram of normal prostate 0.3 ng/ml.
Certain questions need to be clarified before systematically proposing a PSA test to men over 50.
Are all cancers detected after a PSA test clinically important? We know that, at autopsy, many old men have prostate cancer which has never be clinically significant (unfortunately we do not know their pre-mortem PSA value!).
Should we apply a variation according to age? It has been suggested to consider, as an upper PSA limit: 2.5 ng/ml up to 50 years, 3.5 ng/ml up to 60 years, 4.5 ng/ml up to 70 years, and up to 6.5 ng/ml after 70 years.
Should we use the free PSA / total PSA fraction as a way to better differentiate patients requiring biopsy when the total PSA is not very high?
There is generally a long period between the elevation of PSA and the clinical evidence of prostate cancer (at least 5 years). Smith and Catalona demonstrated that the pathological studies in patients who underwent radical prostatectomy because of prostate cancer detected by an elevated PSA revealed that 97% of cases were genuinely evolving cancers.Should we use the increase in the PSA value (the so called velocity) in order to avoid the great personal variability of PSA values?
In fact, the real problem is knowing what to do with a localised prostate carcinoma. Many treatments are aggressive and past controversies between surgeons and radiotherapists have not improved the quality of the debate.
What should be proposed if the biopsy is positive?
Randomised studies comparing the mortality of screened and non screened male populations are rare and although they have been criticised for their methodology, they tend to show that active treatment is necessary. The same conclusion is made in Scandinavian watchful studies and in their long term results.
- radical prostatectomy with many different procedures (open surgery, endoscopy) with a risk of impotence and urinary incontinence which is most often under-evaluated by surgeons,
- radiotherapy with many different procedures (external conformational radiotherapy, brachytherapy, associations) with a risk of impotence and rectal complications, also most often under-evaluated by radiotherapists,
- high-frequency treatments (whose risk is poorly known),
- systematic hormone therapy alone or in association with other treatments,
- watchful waiting - although this attitude has recently been criticised, it could be a possibility for older patients.
Age at diagnosis should be treated with caution. Spontaneous survival according to age is well known. Low histological grade and associated pathologies may indicate watchful waiting or hormone therapy.
However, men who enjoy good health at 75 may live long enough to run the risk of developing metastases and die in pitiful conditions inciting a more aggressive approach to their cancer.
From a practical point of view
Nowadays, in total honesty towards our patients and ourselves, we should recognise that we do not have sufficient knowledge to systematically propose prostate cancer screening. However the American Cancer Society, like the French Urology Association, recommends that all healthy men above 50 have an annual rectal examination and a PSA test. Men with a familial history of prostate cancer should be screened before the age of 50.Our citizens want to be better informed. Before proposing the PSA test, it is necessary to clearly inform them of the consequences of a positive test.
8) Other cancers screening:
Testis cancer
Most testicular cancers are fortuitously discovered by the patient himself (for instance while taking his shower). In the past, diagnosis was often made by army doctors during call-up medical visits. Diagnosis is very simple, based on palpation: every lump in the testis should be investigated by ultrasound and, in the case of doubt, the patient should be referred to a surgeon.The American Cancer Society recommends teaching male adolescents on how to self examine their testes. However the low incidence of this tumour renders a real screening policy difficult to set up.
Skin cancers
The physician should look at the patient’s skin.A patient with many naevi or brown lesions should be advised of the importance of looking out for (or being regularly checked by a physician) any modifications in order to diagnose a melanoma as quickly as possible.
Some lesions, like Bowen's disease , are true in situ skin cancer on unexposed skin surfaces.
When treating elderly people, the physician should be aware that the so-called benign skin epithelioma may give rise to very aggressive tumours, and should be treated as early as possible.
Some parts of the body skin may also degenerate : prudish attitudes should not prevent a clinical examination of vulvar itching to diagnose vulvar carcinoma , likewise itching or haemorrhage for penis carcinoma .
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