The effectiveness of 5-fluorouracil compared to imiquimod for preventing keratinocyte carcinoma is unknown.
To compare the effectiveness of 5-fluorouracil and imiquimod in preventing keratinocyte carcinoma in a real-world practice setting.
We identified 5,700 subjects who filled prescriptions for 5-fluorouracil or imiquimod for actinic keratosis treatment in 2007. An intention-to-treat analysis controlling for potential confounding variables was used to calculate 2- and 5-year cumulative risk differences for subsequent keratinocyte carcinoma overall and in field-treated areas.
5-fluorouracil was associated with a statistically significant decreased risk of any keratinocyte carcinoma compared to imiquimod (adjusted hazard ratio [aHR] 0.86, 95% CI 0.76-0.97), but there were no significant differences in risk by tumor subtype (squamous cell carcinoma aHR 0.89, 95% CI 0.74-1.07; basal cell carcinoma aHR 0.87, 95% CI 0.74-1.03), or site-specific keratinocyte carcinoma (aHR 0.96, 95% CI 0.81-1.14). There were no significant differences in 2- or 5-year cumulative risk for keratinocyte carcinoma among those treated with 5-fluorouracil versus imiquimod.
Generalizability to other practice settings may be limited.
Whereas 5-fluorouracil was more effective in reducing keratinocyte carcinoma risk overall, we found no differences in the short- or long-term risk of subsequent site-specific keratinocyte carcinoma in a real-world practice setting.