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Introduction

Cancer is group of diseases with similar characteristics. Cancer can occur in all living cells in the body and different cancer types have different natural history. Epidemiological studies have shown that 70-90% of all cancers are environmental. Lifestyle related factors are the most important and preventable among the environmental exposures. Tobacco consumptions either as chewing tobacco or smoking tobacco will account for 50% of all cancers in men. Dietary practices, reproductive and sexual practices etc will account for 20-30% of cancers. Appropriate changes in lifestyle can reduce the mortality and morbidity from a good proportion of cancer and heart diseases.

Diet:

The causes of cancer in U.S.A. was estimated by Doll and Peto in 1981. Tobacco was found to be responsible for 25-40% of cancers and diet for 10-70% of cancers. In Kerala tobacco is responsible for 505 of cancer and diet for 10-20%of cancers. Dietary factors may be potentiating the role of other risk factors. Most of the cancers have some relationships with diet predominant among them are cancers of the upper aero digestive tract (mouth, throat), oesophagus (food pipe and lungs), stomach, large intestine, and breast cancer in women.

The idea that nutrition is an important factor in cancer causation is not new. Yong-He Yan living in Song Dynasty( 960-1279 AD) thought that poor nutrition was a cause of the condition now known as oesophageal (food pipe )cancer. Lambe in 1815 warned against the danger of excess consumption of food in general and meat in particular. Roger Williams in 1908 observed that excessive feeding especially meat, deficient exercise and probably lack of sufficient vegetable food are the predisposing factors for cancer. In one of the earliest epidemiological studies on record Orr 91933, who undertook a study in Travancore on oral cancer identified low intake of vegetables and fruits as risk factors. We have not moved far from these observations as we enter into the 21st century.

The role of diet takes special importance in countries like India which are fast moving towards industrialization and westernization. We had a predominantly plant based diet and with the advent of western life style we are moving towards a diet rich in animal proteins. This coupled with other habits like smoking and alcohol will lead to increase in the chronic disease burden especially cancer and cardiovascular diseases. Prompt action has to be taken to spread the message of healthy life style and dietary practices.

Epidemiological Studies:

Descriptive epidemiological studies and International correlation studies have raised specific dietary hypothesis like meat consumption and colon (large intestine) cancer. Studies on migrant populations stressed the role of environmental factors more than genetic predisposition. Japanese have the highest rate of stomach cancer incidents and very low rates of colon cancer and breast cancer. Among the Japanese who have migrated to the USA, their stomach cancer rates have dropped considerably and the rates of colon have increased to that of Americans. These observations were followed by case control and cohort studies which also identified high fat, meat consumption as risk factors and a diet rich in fruits and green and yellow vegetables protective against many cancers.

The biologically active ingredients of the fruits and vegetables are from the carotenoid family and they have substantial anti-cancer properties. Intervention Studies have tried to get the advantage of eating vegetables through supplementation of beta carotene, the most active ingredient.

A study on smokers in Finland infact enhanced the risk of lung cancer among those who took regular supplements of beta carotene. What nature provides in its fullness cannot be encapsulated and there is no substitute for a wholesome healthy diet.

Cancer in Kerala

Population based cancer registries have provided reliable data on the occurrence of cancer in the State. The rate of cancer occurrence in Kerala and in India is much lower compared to Western countries, but the large population will give rise to a large number of cancers. It is estimated that 35,000 new cancer cases occur in Kerala in one year. Among males 50% of cancers in the mouth, throat and lungs are caused by Tobacco and alcohol habits. Among women tobacco related cancers are 15%.

Cancer of the head and neck:

The main risk factor for these cancers is tobacco and alcohol. A diet rich in green and yellow vegetables has been shown to offer protection against oral cancer. Avoidance of tobacco and alcohol is the most important preventive action against mouth, throat and lung cancers.

Cancer of the stomach:

Japanese had the highest rate of stomach cancer of the world and the rates in Japanese migrants have dropped to very low levels as that of Americans when they migrated to the United States. This is clear evidence of the dietary pattern and risk of stomach cancer. The advent of refrigeration has dramatically reduced stomach cancer incidents as it has revolutionized food preservation. Consumption of large amounts of red chillies, food at very high temperatures and alcohol consumption are the main risk factors for stomach cancer in Kerala.

Cancer of the large intestine:

Heavy consumption of red meat can lead to risk of colon cancer. White meat such as that of poultry do not have this risk. There is an international correlation in between the occurrence of large bowel cancer and consumption of red meat. In South India there is a trend towards increasing consumption of red meat and this can lead to increased risk for large bowel cancer.

Cancer of the breast in women:

A large number of factors are identified as risk factors for breast cancer. Late age at first pregnancy greater than 30 years, single child, late age at menopause etc are some of them. A high fat diet is also identified as a risk factor. Physical activity is found to be protective for breast cancer. The sudden changes towards affluent life styles have reduced the physical activities to a minimum and increased the consumption of diets rich in fat. High fat diets during the pubertal age and obesity in the post menopausal age are risk factors for breast cancer.

Regular breast self examination by women themselves is a very good way of detecting breast cancer in early stages. Detecting a cancer when it is in the very early stage can improve the cure rate from breast cancer. Mammography (X-rays of the breast ) is another way of detecting breast cancer that cannot be palpated by hand.

Cancer of the uterine cervix:

Early age at first intercourse, multiple sexual partners, poor sexual hygiene, repeated child birth etc are some of the reproductive risk factors for cervical cancer. Improvements in the living standards of women has resulted in a reduction in the incidents of cervical cancer. Regular cervical cytology examination (pap smear) by all women who have initiated sexual activity can prevent the occurrence of cervical cancer. This has been successfully achieved in many European countries.

 

 

 

 

 


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