CANCER

Cancer

The term cancer is a generalized and refers to a group of more than 100 diseases that can affect any part of the body. It can also be referred as malignant tumours and neoplasms. One definite characteristics of cancer is that there is uncontrolled growth of abnormal cells beyond the usual boundaries, and often spread to other parts of the body. The spreading is called as metastasis and it is the major cause of deaths in persons suffering from cancer.

FACTS ABOUT CANCER

Cancer is a leading cause of death worldwide. From a total of 58 million deaths worldwide in 2005, cancer accounts for 7.6 million (or 13%) of all deaths. The main types of cancer leading to overall cancer mortality are:

• lung (1.3 million deaths/year);
• Stomach (almost 1 million deaths/year);
• Liver (662,000 deaths/year);
• Colon (655,000 deaths/year) and
• Breast (502,000 deaths/year).

More than 70% of all cancer deaths in 2005 occurred in low and middle income countries. Deaths from cancer in the world are projected to continue rising, with an estimated 9 million people dying from cancer in 2015 and 11.4 million dying in 2030.
The most frequent cancer types world wide are:

• Among men (in order of number of global deaths): lung, stomach, liver, colorectal, oesophagus and prostate.
• Among women (in order of number of global deaths): breast, lung, stomach, colorectal and cervical.

QUICK CANCER FACTS

• 40% of cancer can be prevented (by a healthy diet, physical activity and not using tobacco).
• Tobacco use is the single largest preventable cause of cancer in the world. Tobacco use causes cancer of the lung, throat, mouth, pancreas, bladder, stomach, liver, kidney and other types; Environmental tobacco smoke (passive smoking) causes lung cancer.
• One-fifth of cancers worldwide are due to chronic infections, mainly from hepatitis B viruses HBV (causing liver), human papilloma viruses HPV (causing cervix), Helicobacter pylori (causing stomach), schistosomes (causing bladder), the liver fluke (bile duct) and human immunodeficiency virus HIV (Kaposi sarcoma and lymphomas).

Causes of Cancer

Cancer usually occurs if there is any change in the genes responsible for cell growth and repair. These changes can arise as a result of the interaction between genetic host factors and external agents which can be categorized as:

• physical carcinogens such as ultraviolet (UV) and ionizing radiation
• chemical carcinogens such a asbestos and tobacco smoke
• biological carcinogens such as
• infections by virus (Hepatitis B Virus and liver cancer, Human Papilloma Virus (HPV) and cervical cancer) and bacteria (Helicobater pylori and gastric cancer) and parasites (schistosomiasis and bladder cancer)
• contamination of food by mycotoxins such as aflatoxins (products of Aspergillus fungi) causing liver cancer.

Tobacco use is the single most important risk factor for cancer and causes a large variety of cancer types such as lung, larynx, oesophagus, stomach, bladder, oral cavity and others. Although there are still some open questions, there is sufficient evidence that dietary factors also play an important role in causing cancer. This applies to obesity as a compound risk factor per se as well as to the composition of the diet such as lack of fruit and vegetables and high salt intake. Lack of physical activity has a distinct role as risk factor for cancer. There is solid evidence about alcohol causing several cancer types such as oesophagus, pharynx, larynx, liver, breast, and other cancer types.

Development of cancer

Cancer arises from one single cell. The transformation from a normal cell into a tumor cell occurs in more than one step, typically a progression from a pre-cancerous lesion to malignant tumors. The development of cancer may be initiated by external agents and inherited genetic factors. Ageing is another fundamental factor for the development of cancer. The incidence of cancer rises dramatically with age, most likely due to risk accumulation over the life course combined with the tendency for cellular repair mechanisms to be less effective as a person grows older.

Reducing the burden of cancer

The existing body of knowledge about the causes of cancer and about interventions to prevent and manage cancer is extensive. The burden of the cancer can be reduced to a considerable extent by employing the following strategies.

• changes in tobacco and alcohol use, and dietary and physical activity patterns
• immunization against HPV infection
• the control of occupational hazards
• reducing exposure to sunlight

Another third of the cancer burden could be cured if detected early and treated adequately.
Early detection of cancer is based on the observation that treatment is more effective when cancer is detected earlier. The aim is to detect the cancer when it is localized. There are two components of early detection programmes for cancer:

• Education to promote early diagnosis by recognizing early signs of cancer such as: lumps, sores, persistent indigestion, persistent coughing, and bleeding from the body's orifices; and the importance of seeking prompt medical attention for these symptoms.
• Screening is the identification by means of tests of people with early cancer or pre-cancer before signs are detectable. Screening tests are available for breast cancer (Mammography) and cervical cancer (Cytology tests).
• Treatment of cancer is aimed at curing, prolonging life and improving quality of life of patients with cancer. Some of the most common cancer types such as breast cancer, cervical cancer and colorectal cancer have a high cure rate when detected early and treated according to best evidence. The principal methods of treatment are surgery, radiotherapy and chemotherapy. Fundamental for adequate treatment is an accurate diagnosis by means of investigations involving imaging technology (ultrasound, endoscopy, radiography) and laboratory (pathology).
• Relief from pain and other problems can be achieved in over 90% of all cancer patients by means of palliative care. Effective strategies exist for the provision of palliative care services for cancer patients and their families, even in low resource settings.