"While few epidemiologic studies have examined the relationship of sunscreen use and skin cancer, two studies suggest that sunscreens may not be effective in preventing skin cancer. A large case-control study showed higher risks of melanoma in men who used sunscreens, and a large prospective study showed a higher incidence of basal cell carcinoma in women who used sunscreens. The excess risks in the latter study persisted after multiple adjustment for differences in skin type and time spent outdoors."
This is from 1992 and earlier, though. One wonders if there has been any more progress in recent years.
And here is where I get to rant about my own pet peeve: Why should I be surprised that so few people know how to properly cite scientific literature? That literature is locked behind paywalls! I'm not going to even bother using PubMed on this, and it's only partly because I don't care. It's mostly because, even if I turn up a definitive set of review papers in Nature on this very topic, I won't be able to read them without paying $15 each, or whatever.
I'm not sure if you are referring to the article I quoted or to its references... but the page that I linked to let me download the article directly for free, despite a sidebar link that purportedly also allows you to purchase the article. (I was surprised, too.)
I, too, wonder if there aren't more recent studies. The two studies cited were from 1985 and 1990, though; if that's the most they could come up with in 1992, it sounds like the area is sparsely researched.
The references, of course. It's hard to operate without them. Particularly when you're outside of your own field, and can't just name the various schools of thought -- and the major authors and manuscripts associated with them -- off the top of your head.
"While few epidemiologic studies have examined the relationship of sunscreen use and skin cancer, two studies suggest that sunscreens may not be effective in preventing skin cancer. A large case-control study showed higher risks of melanoma in men who used sunscreens, and a large prospective study showed a higher incidence of basal cell carcinoma in women who used sunscreens. The excess risks in the latter study persisted after multiple adjustment for differences in skin type and time spent outdoors."
-- "Could Sunscreens Increase Melanoma Risk?" http://www.ajph.org/cgi/reprint/82/4/614