Cancer Survival Tied to Season of Diagnosis, Sunlight Exposure

NEW YORK OCT 18, 2006 (Reuters Health) - The season in which cancer is diagnosed appears to affect survival, as does sunlight exposure to some extent, according to a study published in the October issue of the International Journal of Cancer. 

"Sunlight is essential for the production of vitamin D in the body," Dr. Hyun-Sook Lim, of King"s College London, UK, and colleagues write.  "Evidence exists to suggest that vitamin D metabolites may have a role in tumor growth suppression."

The researchers used data from the Thames Cancer Registry to assess survival for cancers of the breast, colorectum, lung, prostate, and all sites combined, in relation to season of diagnosis and sunlight exposure.

Patients who were diagnosed with cancer in summer and autumn had better survival compared to those diagnosed in winter.  This was especially true in female breast cancer patients and both male and female lung cancer patients. The beneficial effect on survival was also observed for cancers at all sites combined in both sexes.

Cumulative sunlight exposure in the months preceding cancer diagnosis also predicted subsequent survival.  However, season of diagnosis was a stronger predictor.

"Our results add to a growing body of evidence that vitamin D may play an important role in cancer survival," the investigators conclude.

SOURCE:

Int J Cancer 2006;119:1530-1536.


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