Cancer a group of diseases characterized by abnormal proliferation of cells, usually in a random, disorderly manner. Through the uncontrolled growth of these malignant cells tumors are usually formed. These crowd out healthy tissue and eventually interfere with the vital functioning of affected organs. Malignant cells tend to spread from their site of origin by travelling through the blood stream or lymphatic system.

There are many types of cancer. Some, like lung or bowel cancer, are common; others are rare. The likely cause remains unexplained. Triggering agents include chemicals such as those found in cigarette smoke, other forms of smoke, asbestos dust, exhaust fumes, and many industrial chemicals. Some viruses can also trigger the cancerous growth of cells, as can x-rays and radioactivity.

Cancer poses serious health problems both in developed and developing countries. The prevention and control of cancer in developing countries deserve urgent attention since the disease is expected to double in these countries in the next 20 to 25 years. The problem of cancer in Bangladesh is a particularly acute because of poverty, illiteracy, and other diseases associated with poor nutrition and lack of basic knowledge of people about health matters.

Cancer control means its primary prevention, early detection (ie secondary prevention), treatment, follow-up, treatment of recurrent cases, and palliative care, including relief of pain of advanced and incurable cases. In other words, the real object of cancer control is to minimize the total impact of cancer by reducing mortality from cancer.

No reliable statistical data about cancer are available for most developing countries in general, and Bangladesh in particular. In the light of the statistics available from the World Health Organisation, cancer incidence, prevalence and mortality can be estimated approximately as 2,00,000, 8,00,000 and 1,50,000 respectively for the 130 million people of Bangladesh. Based on the World Health Statistics, new cancer cases in Bangladesh have been estimated at 167 per 1,00,000 population.

Common cancers in Bangladesh Based on the data available from the Radiotherapy Department of the dhaka medical college and hospital, common cancers in males and females can be figured out as shown in table.

Table 1 Relative percentage of common cancers in Bangladesh.

Male % Female %
Lung 21 Cervix 24
Larynx 13 Breast 17
Oral cavity 12 Oral cavity 13
Leukaemia/Lymphoma 8 Ovary 6
Pharynx 6 Leukaemia/Lymphoma 5
Oesophagus 5 Oesophagus 4
Others 35 Others 31

Source Based on 21,238 cancer (Male 14,222 and female 7,076) treated at the Radiotherapy Department of Dhaka Medical College Hospital during the period of 1985-92.

Causes tobacco smoking is the major cause of lung cancer. About 85 percent of lung cancer cases are caused by smoking. This cancer causes death to about 35 percent of all cancer patients in developed countries and about 21 percent of all cancer patients among men in Bangladesh.

Tobacco chewing is an important cause of oral cancer and account for about 13 percent of all cancers in Bangladesh. Most people of the country generally use tobacco products such as raw tobacco leaf, Jarda, Kimam, etc with betel leaf, betel nut, slaked lime and catechu that are responsible for oral cancer. Use of Gul and Khaini are responsible for cancers of gum and cheek. Use of snuff may cause nasal cancer as well. Bad oral hygiene and poor dental care are also responsible for cancer of oral cavity.

Use of tobacco is not only responsible for causing cancers of the lung and oral cavity, but is also responsible for causing cancers of the larynx, pharynx, esophagus, pancreas, kidney and bladder. About 50 percent of all cancers in this country can be prevented in Bangladesh if smoking and chewing tobacco is stopped.

Table 2 Prevalent cancers in Bangladesh and their risk factors.

Sites Risk factors
Lung, Larynx Tobacco smoking
Oral cavity Tobacco chewing
Pharynx Air pollution and chemicals: Asbestos (Lung)
Oesophagus Poor dental care and oral hygiene (oral cavity)
Pancreas Excessive intake of red chilli (oesophagus)
Kidney, Bladder Early sex, early marriage, multiple sex partners, multiple pregnancies, low socio-economic status, poor personal hygiene, venereal diseases
Cervix HSV-2, HPV, Uncircumcised male partner, nulliparous
Breast Daughters of breast cancer patients, less breast feeding, high fatty food, alcohol drinking (+tobacco smoking)
Liver HBV
Stomach High fatty food
Colo-rectum Low fibrous food, low Vitamin A,C,E, and Selenium, Zinc in food
Penis Uncircumcised male organ

Cervical cancer, the most common cancer affecting women of Bangladesh is probably due to repeated childbirth resulting in lacerations of the cervix and cervicitis. This cancer can be minimised by limiting the number of children. Early sex life, early marriage, multiple sexual partners, venereal disease, Herpes virus, human papilloma virus, low socio-economic status, and poor personal hygiene are also associated with higher incidence of cervical cancer. Prostitutes have very high risk of cervix cancer.

The practice of circumcision greatly reduces the risk of penile cancer in males and to some extent of cervical cancer in female partners.

Breast cancer is the second commonest cancer among women of Bangladesh. Nulliparous women, daughters of breast cancer patients, and those who do not breast-feed their babies and indulge in high-fat diet suffer more from breast cancer.

Cancer of oral cavity, larynx, oesophagus, and particularly of liver occur more frequently among heavy drinkers of alcohol, specially when accompanied by smoking and chewing of tobacco. Hepatitis B virus is also responsible for liver cancer against which a successful vaccine has been developed and is in use. Aflatoxins produced by the fungus developed in most carbohydrate foods in hot, humid climates are highly carcinogenic for the liver.

High fatty food may cause certain cancers such as breast, colo-rectum, uterus and prostate cancer. High fibrous food, on the other hand, helps reduce the risk of colon cancer and foods rich in vitamins A, C, E for cancers of larynx and lung.

Prevention of cancer At present, about one-third of the cancers affecting people can be prevented; one third can be cured, and palliation is possible for the rest. Recent data from developed countries show that there has been a decline in all cancer deaths except lung cancer. Early diagnosis, improved treatment, and appropriate change in life style have led to this development. Rise of total cancer deaths is due to consumption of tobacco.

Prevention of cancer may be primary or secondary. Primary prevention indicates steps to be taken before the development of the disease, for which one must know the causes of cancer, must take measures to avoid them and must make appropriate changes in ones lifestyle.

Secondary prevention of cancer involves early detection of the disease through increased awareness achieved by imparting knowledge of early signs and symptoms of cancer, by screening through promotion of self-examination of breast and mouth, by periodic check-ups, eg X-ray of chest, mammography, and by other special examinations.

Control of cancer Cancer control programme comprises a series of activities to diminish the total impact of cancer in any community or country by prevention, early detection, and the provision of facilities for appropriate treatment at an early stage of the disease. Also included are follow-up and rehabilitation of the treated cases, treatment of recurrent cases, and relief of pain for patients with incurable cancers. Evaluation of the programme is necessary from time to time as per data provided by the Cancer Registry.

The Bangladesh Cancer Society has prepared 'A Plan for Cancer Control in Bangladesh' and formally handed it to the Government for implementation. The plan recommends: (i) primary prevention of cancers related to the use of tobacco, ie those of the lung, oral cavity, larynx, and esophagus; (ii) development of facilities for early diagnosis of cervical, oral, and breast cancers and treatment of these and other cancers in existing institutions and other centres in due course; (iii) efforts for early diagnosis through increased awareness by imparting knowledge of early signs and symptoms of cancer and by promoting self-examination of breast and mouth, and where possible down-staging with cytology; (iv) measures for relief of pain for patients with advanced cancer; (v) training programmes for specialists and technicians, and (vi) setting up a National Cancer Registry in order to monitor the status of cancer in Bangladesh.

The plan calls for a firm political commitment by the Government for implementation of the programme and allocation of necessary funds. There are reasons to believe that the programme for prevention of cancer can be profitably integrated with those for Primary Health Care and Family Welfare. [Sayyid Fazlul Huq]

Breast Cancer A malignant neoplasm of the breast. Breast cancer is an important health problem of women between the age of 40 and 50. Most cancers of the breast occur in the duct of the milk-secreting gland, while some originate at the gland itself. Early sign is usually the appearance of a lump in the breast that slowly enlarges with passage of time. Seeking immediate medical advice is recommended should these signs are detected.

There is no accurate data on the incidence of breast cancer in Bangladesh. Figures available suggest that about 200,000 patients are treated for cancer every year and that the yearly death toll is 150,000 per year. There is no statistics as to how many of these are breast cancer cases. But it would probably be quite small since breast cancer cases at the early stage of illness are rarely reported to physicians. In cities and towns this medical non-compliance is mainly due to lack of facilities, while in rural areas the social inhibition also plays in a role. Based on the data available from the Radiotherapy Department of the Dhaka Medical College Hospital, it is estimated that the incidence of breast cancer will be about 17%.

Since the early 1990s there has been considerable improvement in diagnostic health services that have coincided with the country's entry into free market economy. Mammography, which is a special imaging technique using x-rays, came to be available in the private sector at about this time. The technique visualises soft tissue of the breast making it easy to detect breast cancer. In a small number of Dhaka private clinics, mammography facilities are available that are used in suspected cases of breast cancer, while a small number of users take the test for monitoring purpose. Between the age of 35-40, it is recommended that a woman should take a mammogram once in two years up to the age of 50, and once a year after 50. However, some recent studies seem to suggest that routine monitoring for breast cancer by mammograms may not be very useful for women under the age of 50. [Zia Uddin Ahmed]