Previous studies have suggested that people who live in southern regions are at greater risk for non-Hodgkin’s lymphoma, leading researchers to hypothesize that exposure to sunlight may play a role in causing the lymph tissue cancer.
But a new study, published in the March 1st issue of the International Journal of Cancer, contradicts this theory. An international team of researchers studying people living in Sweden has found no link between sunlight exposure in individuals — as measured by job description — and non-Hodgkin’s lymphoma.
Although using a person’s job description may be a rough way to measure sunlight exposure, the findings suggest that exposure to ultraviolet rays in sunlight is not a major cause of the disease, according to Dr. Johanna Adami from the Karolinska Institute in Stockholm, Sweden, and colleagues.
Cases of non-Hodgkin’s lymphoma are increasing in most Western countries by 3% to 4% per year, and the reason why is unclear.
In the study, Adami and colleagues examined information on more than 4 million people in the Swedish Cancer-Environment Registry, including details about their occupation in 1960 and 1970, and their place of residence.
The investigators found that people who lived in southern regions were indeed at greater risk for non-Hodgkin’s lymphoma, as well as skin cancers such as malignant melanoma and squamous cell carcinoma. However, there was no link between sun exposure, as estimated by occupation, and the cancer.
The findings do confirm the connection between residence in southern regions and non-Hodgkin’s lymphoma, but do not support the theory that exposure to ultraviolet light is the cause of the increased cancer risk, Adami and colleagues conclude.
Tags: cancer, lymphoma, melanoma