medwireNews: A single course of topical fluorouracil can prevent the occurrence of cutaneous squamous cell carcinoma (SCC) requiring surgery in the first year after use, trial results suggest.
Noting the aggressive nature of cutaneous SCCs and the fact that the number of lesions tends to increase over time, the investigators highlight that “[t]his trial demonstrates a proactive approach that is effective.”
They add: “Topical fluorouracil is the first agent we know of that demonstrates extended posttreatment effects in SCC chemoprevention.”
In the double-blind Veterans Affairs Keratinocyte Carcinoma Chemoprevention Trial, individuals with a history of two or more keratinocyte carcinomas in the previous 5 years (98% men; median age 70 years) were randomly assigned to apply either topical fluorouracil, 5%, or vehicle control cream twice daily to their face and ears for 2–4 weeks.
Martin Weinstock, from the Providence Veterans Affairs Medical Center in Rhode Island, USA, and co-researchers report that the trial did not meet its primary endpoint, with no significant differences between the topical fluorouracil and control treatment arms in terms of time to first keratinocyte carcinoma, BCC, or SCC over the 4 years of the study.
During the first year after use, however, SCCs developed in five of 468 fluorouracil-treated individuals and 20 of 464 controls, equating to a significant 75% reduced risk for developing cutaneous SCCs with fluorouracil treatment relative to the control cream.
By contrast, there was no significant effect on the risk for developing basal cell carcinoma (BCC) in the first year, nor on the year 1 overall keratinocyte carcinoma risk.
But topical fluorouracil treatment appeared to significantly reduce the proportion of patients requiring Mohs surgery for at least one BCC or keratinocyte carcinoma in year 1, with risk ratios relative to the control group of 0.51 in each case.
Despite “the expected adverse effects of fluorouracil,” including erythema and crusting, the investigators note that 87% of fluorouracil-treated participants indicated a willingness to repeat the treatment if shown to be effective in reducing future incidences of keratinocyte carcinomas.
And they conclude in JAMA Dermatology: “It is reasonable at this point to consider the use of a standard and perhaps annual course of topical fluorouracil, 5%, to the face and ears for the reduction of SCC risk in high-risk populations, and potentially for a reduction in need for Mohs surgery.
“[M]ore detailed study could define precisely the groups that would most benefit.”
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