Some risk factors that have been identified for stomach cancer are employment in dusty occupations, inheritable conditions, and a minor influence of smoking, and dietary factors. Several studies have shown that a high intake of salt and preserved meat or fish increases the risk for stomach cancer. The factor that has been investigated most extensively is dietary. As with lung cancer, it has been shown that people with the highest intake of fruit and vegetables have half the risk of developing stomach cancer compared to people with the lowest intake of fruit and vegetables. A decrease in the use of preserved foods and salt, along with an increased intake of fruit and vegetables can explain the world-wide decline in stomach cancer.
Prostate cancer is the fourth most common cancer of men world-wide.
The most important risk factor for prostate cancer is inheritance. Men who have a father or brother with prostate cancer have twice the risk of developing the cancer than those men without a family history of the disease. The risk increases if there is more than one affected relative or if a relative developed the disease at a young age. Large variations in incidence rates between countries, along with the increase in rates in migrants from low risk areas to high risk areas, suggest that environmental factors are involved. Current research has concentrated on hypotheses involving sexual activity or diet.