Q Do you know of any effective treatment for solar keratoses, an early form of skin cancer caused by overexposure to the sun? - Mrs S.A. Morrill, Hereford
A Solar, or actinic keratoses (AK), or sunspots, are sandpapery patches of grey or pink skin that may become wart-like, and are often itchy or prickly, on sun-exposed parts of the body. Although thought to be due to overexposure to the sun, AK can strike even in Britain's temperate climate, mostly affecting fair-skinned people, the very young and the old. However, the risk of AK becoming squamous cell skin cancer within one year is less than one in 1000 (Lancet, 1988; i: 795-7). Most lesions will go away on their own.
Conventional treatments for AK include freezing with liquid nitrogen (cryotherapy), creams containing 5-fluorouracil (an anticancer agent), surgical removal, and photodynamic or laser therapy. That there are so many treatments suggests that none is truly satisfactory.
However, neither are any of the alternatives, at least according to the evidence so far. Alpha-hydroxy acids, such as glycolic and lactic acids, are derived from fruit and dairy products. Milder relatives of the compounds used by dermatologists for chemical peels that remove damaged skin, in recent years, cosmetic manufacturers have begun to add AHAs to numerous skincare products.
There is modest evidence that AHAs can help sun-damaged skin (Arch Dermatol, 1996; 132: 631-6), but their side-effects - such as burning, blistering and sun-sensitivity - are clearly counterproductive.
Early trials found that a vitamin C-containing cream produced positive changes in sun-damaged skin (Arch Otolaryngol Head Neck Surg, 1999; 125: 1091-8), but the evidence is not definitive.
Grape skin and pine bark contain OPCs (oligomeric proanthocyanidin complexes), which appear to strengthen collagen and elastin, suggesting some value for skin damage. Again, however, their use is not backed up by any formal evidence of benefit.
Medicine is now veering toward natural ingredients - albeit in adulterated forms. One such is colchicine, from crocuses. As a 'mitotic inhibitor', this plant alkaloid may be able to stop cancer-cell reproduction in its tracks.
Indeed, in a randomised double-blind study of 20 patients with AK, seven out of 10 using colchicine gel had a complete healing of lesions. But there's one caveat: all of the colchicine users had itching and burning initially, and skin inflammation wherever the gel was applied (Dermatology, 2000; 200: 346-8).
Masoprocol (used in Actinex) is derived from the chaparral shrub native to the American Southwest. It also inhibits cancer-cell proliferation but, like colchicine, it causes a burning contact dermatitis.
There's Elicina cream, which claims to treat damaged skin, including AK. It contains a substance produced by the Chilean snail Helix aspersa M"uller to regenerate its own shell and skin damage. Again, we could find no scientific evidence to support its claims, but we also found no complaints of dermatitis.
Finally, you could try aloe vera. One WDDTY reader with basal-cell skin cancer used aloe vera skin gel (the highest potency available) on it - it worked within two weeks (see WDDTY vol 12 no 6).