I almost fell of office chair yesterday when I read this article in the UK’s Daily Mail by oncologist (cancer specialist) Professor Angus Dalgleish. Professor Dalgleish has a particular interest in malignant melanoma. In the piece, he draws our attention to the links between vitamin D and cancer, including the link between low vitamin D levels and melanoma. He warns that the anti-sun propaganda many us have been familiar with for much of our lives may well have led to a chronic deficiency of vitamin D. The implication is clear: our advice about sun exposure may be contributing to increasing cancer incidence, including melanoma.
Back in April, one of my blogs focused on the relationship between sunlight and melanoma, and presented some observations from dermatologist Dr Sam Shuster including the fact that:
- The relationship between melanoma and latitude is small and inconsistent (in other words, locations closer to the equator with more sunlight exposure do not see very significantly increased malignant melanoma incidence).
- Malignant melanoma incidence and death from this condition are lower in individuals with increased sunlight exposure (11 studies are cited as evidence to support this).
- Incidence of malignant melanoma is not reduced and can be increased by sunscreen use.
- Melanoma risk associated with sunbed use is “small and inconsistent”.
- Inducing malignant melanoma in the laboratory using ultraviolet light is difficult (in contrast to other less aggressive and more treatable skin cancers).
Professor Dalgleish’s comments further call into question the general advice we have about sun exposure, and the risks it poses regarding melanoma specifically. His ideas go against the grain of conventional thinking somewhat, and I believe he should be applauded for injecting some objectivity into the debate.
I don’t know Professor Dalgleish personally, but my suspicion is he is a man who thinks for himself and is interested in giving the best care and advice possible to his patients. I also think it’s probably true that he and his department receive no funding from the manufacturers of sunscreen…