How do cure rates for topical fluorouracil compare with surgical excision and Mohs surgery for superficial basal cell carcinoma?
Executive summary
For superficial basal cell carcinoma (sBCC) Mohs micrographic surgery produces the highest reported long-term cure rates (approaching 99%), standard surgical excision typically cures roughly 90% of cases, and topical 5% fluorouracil yields lower and more variable clearance rates—commonly reported between about 68% and 80% in published series and randomized trials (Mohs ≈99%; excision ≈90%; topical 5-FU ≈68–80%) [1] [2] [3]. The evidence base shows surgery as the gold standard while topical 5-FU is an accepted, non‑invasive option for selected, low‑risk, epidermally confined lesions and for patients who decline or cannot undergo procedures [4] [5].
1. Mohs sets the benchmark: near‑universal clearance for appropriate sBCCs
Multiple authoritative sources and systematic comparisons describe Mohs micrographic surgery as having the highest cure rate of any modality for non‑melanoma skin cancer, with long‑term clearance rates reported near 99% for appropriately selected lesions, which is why Mohs is the preferred option for high‑risk, recurrent, or cosmetically sensitive sBCCs [1] [2] [6].
2. Standard excision: high success but measurably below Mohs
Standard surgical excision achieves very good outcomes—commonly cited around a 90% cure rate for sBCC—making it an effective first‑line choice for many small, low‑risk lesions; excision is less tissue‑sparing and offers less immediate microscopic margin control than Mohs, which explains the gap in recurrence/clearance figures [1] [7].
3. Topical 5‑fluorouracil: effective, less predictable, and patient‑dependent
Topical 5% fluorouracil is approved and widely used for epidermally limited lesions and preventive field therapy, but its complete clinical response and cure rates are lower and more variable than surgical options—trial and cohort data report a range (for sBCC and related superficial keratinocyte cancers) from roughly the high‑60s up to ~80% depending on regimen, lesion selection, and follow‑up duration, and retrospective analyses caution that real‑world effectiveness can diverge from clinical trial results [3] [8] [9].
4. Why numbers differ: lesion selection, follow‑up, and study design matter
Comparisons are confounded by differences in which lesions were treated (true superficial vs. deeper subtypes), how strictly “clearance” was defined, treatment duration and adherence (5‑FU is commonly applied twice daily for 28–42 days), and length of follow‑up; head‑to‑head randomized trials are limited, and retrospective cohorts show that topical 5‑FU can be noninferior in selected circumstances but often performs worse when applied to lesions that would better suit excision or Mohs [9] [8] [4].
5. Clinical implications: tradeoffs between cure, cosmesis, cost and access
Surgery (Mohs or excision) maximizes the chance of definitive cure and margin control—favored for facial, recurrent, or aggressive lesions—while topical 5‑FU offers a non‑surgical, scar‑sparing alternative for small, superficial, low‑risk tumors or for patients prioritizing noninvasive care; practical considerations such as limited access to Mohs surgeons, cost, patient comorbidities, and desire to avoid surgery influence choice, and some clinicians use 5‑FU as adjunctive or presurgical therapy to delineate margins or treat residual superficial foci [5] [4] [6].
6. Limits of the reporting and where uncertainty remains
Available sources consistently rank Mohs highest and show excision superior to topical 5‑FU on average, but the literature contains heterogeneity in outcomes and sparse rigorous, modern head‑to‑head trials focused exclusively on sBCC; therefore conclusions apply best to appropriately selected lesions and patients, and treatment decisions should integrate tumor subtype, location, patient preferences, and local expertise [9] [4] [8].