A. The most important factors increasing probability of cancer common for all the three sites:

1. SMOKING―especially of cigarettes without filters; more than 20 cigarettes a day; a long history of smoking.

2. OVERINDULGENCE IN ALCOHOL.

3. EMPLOYMENT IN ANY INDUSTRY.

4. “UNCOMFORTABLE” HOUSING (no piped water supply, poor sanitation, use of indoor coal burners for heating, water boiling and especially for cooking).

5. COAL-FIRED KITCHEN OVEN (irrespective of housing type).

6. BEING A PERMANENT RESIDENT (as opposed to immigrant).

For lung cancer only: CHRONIC BRONCHITIS.

For gastric cancer only: CHRONIC GASTRITIS AND GASTRIC ULCER.

For colorectal cancer only: LIVER DISEASES.

B. Factor decreasing probability of gastric and colorectal cances: PREFERRING MILK-VEGETABLE-FISH DIETS.