ABSTRACT

The incidence of non-Hodgkin’s lymphoma (NHL) in North America has been rising for the past 50 years at a rate of approximately 2-3% per year. It has become the fourth most common type of cancer for adult men (after lung, prostate, and colorectal) and women (after lung, breast, and colorectal) reaching an incidence of approximately 15 cases per 100,000 per year in women and 25 cases per 100,000 per year in men and causing approximately 60,000 new cases annually. The reason for this rise is unknown, though three observations may be relevant. Firstly, although a modest contribution to this rise has come from the cases seen in patients with

AIDS, most of the increase has occurred in the elderly. Secondly, workers in occupations such as farming, processing of forestry products, paper processing, and others that involve long-term exposure to bioactive solvents and reagents have an increased risk of developing NHL, which is 1.5-4.0 times normal. Thirdly, the increase in lymphomas is exactly parallel to that seen in melanoma, the only other cancer with a rising incidence unrelated to smoking. It is possible that exposure to solar radiation plays a role in both increases.