To minimize the duration of side effects, compliance issues and phone calls when prescribing 5-FU prescribe 0.5% 5-FU therapy for 1 week. Phase 3 FDA data on 0.5% 5-FU used for 1 week demonstrate over 70% individual lesion clearance. Is it worth continuing an extra 3 weeks to achieve a > 90% clearance? No.
What does Dr. George Martin do? He cycles 5-FU therapy: 1st cycle—Face: 7 days 5-FU/Non-facial areas: 10 days 5-FU; Rest period for at least one month; 2nd cycle— 5-FU for at least 2 weeks. Data suggest that 0.5% 5-FU QD is at least as effective as 5% 5-FU BID in percent reduction of AK lesions. The short treatment cycles result in great compliance and minimal downtime.
Treating AKs on the chest?
Avoid 3.75% imiquimod. It is likely to result in permanent depigmentation at the AKs treated sites on the chest in the majority of patients. It is not yet FDA approved for the trunk…and with good reason.
Try: ingenol mebutate 0.05% x 2 nights. Instead of spot treating, cover the entire sun-damaged AK area of the chest with the entire amount in the tube. Best used on moistened skin post shower because it spreads better. Because of its direct cytotoxic effect, in addition to up-regulation of IL-8 induced neutrophil chemotaxis, it produces discomfort within 4 hours requiring analgesia. Be sure to set patient expectations and prescribe analgesia. Patients describe it’s use on large areas on the upper chest as feeling like a “really bad sunburn.” Although not FDA approved to treat areas >25 cm2 and there is no efficacy data, Dr. Martin has found it to produce excellent AK clearance and a great cosmetic result.
