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Cancer survival is dependent on season of diagnosis and sunlight exposure
Author(s) -
Lim HyunSook,
Roychoudhuri Rahul,
Peto Julian,
Schwartz Gary,
Baade Peter,
Møller Henrik
Publication year - 2006
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.22052
Subject(s) - sunlight , medicine , breast cancer , proportional hazards model , lung cancer , cancer , vitamin d and neurology , cancer registry , hazard ratio , prostate cancer , population , seasonality , relative survival , oncology , physiology , environmental health , biology , confidence interval , physics , ecology , astronomy
Sunlight is essential for the production of vitamin D in the body. Evidence exists to suggest that vitamin D metabolites may have a role in tumor growth suppression. In this large study, involving over a million cancer patients from the United Kingdom, we have analyzed the role of season of diagnosis and sunlight exposure in cancer survival for cancers of the breast, colorectum, lung, prostate and at all sites combined. We used population‐based data from the Thames Cancer Registry to analyze cancer survival in periods 0–1 and 0–5 years after diagnosis. The analysis was performed using Cox proportional regression analysis adjusting for age and period at diagnosis and including season of diagnosis and sunlight exposure in the preceding months as factors in the analysis. We found evidence of substantial seasonality in cancer survival, with diagnosis in summer and autumn associated with improved survival compared with that in winter, especially in female breast cancer patients and both male and female lung cancer patients (hazard ratios 0.86 [95% CI 0.83–0.89], 0.95 [95% CI 0.92–0.97] and 0.95 [95% CI 0.93–0.98] respectively). Cumulative sunlight exposure in the months preceding diagnosis was also a predictor of subsequent survival, although season of diagnosis was a stronger predictor than cumulative sunlight exposure. We found seasonality in cancer survival to be stronger in women than in men. Our results add to a growing body of evidence that vitamin D metabolites play an important role in cancer survival. © 2006 Wiley‐Liss, Inc.