Hypofractionated electron beam RT for epithelial skin cancer, 434 cases
ForBiopsy-proven BCC or SCC, mostly head/face, elderly, primary or postop residual
TL;DR3-yr actuarial LRF 97.5% (54 Gy/18fx) vs 96.1% (44 Gy/10fx) with electrons for BCC/SCC; no significant difference in either histology.
The boundary is size: T3 tumours >5 cm recurred in 2/11, both after 44 Gy, so the centre now gives 54 Gy above 5 cm. SCC behaves differently from BCC. SCC recurrences came early (median 3.3 mo) and 3 of 5 had metastases. All BCC recurrences were local-only and treated by excision. Technique was a 1 cm margin with copper-foil compensation for skin sparing.
In an elderly pt with T1-T2 BCC or SCC on the face or head treated with electrons, this supports 44 Gy/10 fx as a convenience schedule equivalent in observed control to 54 Gy/18 fx; it does not extend to lesions >5 cm.
Size sets the limit: T3 >5 cm recurred in 2/11, both after 44 Gy, and the centre now uses 54 Gy above 5 cm. SCC failures came early (median 3.3 mo) and 3 of 5 had metastases. BCC failures were local-only and treated by excision. Technique was a 1 cm margin with copper-foil surface compensation.
15 details
Retrospective single-centre series, 434 tumours in 333 pts treated January 2001 to December 2006. Analysis per tumour; LRF and MFS as one minus cumulative incidence with death as competing risk.
Biopsy-proven BCC (n=332) or SCC (n=102), primary RT (n=386) or postop for residual disease (n=48). Median age 74.8y BCC, 78.3y SCC; 59.4% face, 22.4% elsewhere on head.
Electrons, 54 Gy/18 fx of 3 Gy (n=159) or 44 Gy/10 fx of 4.4 Gy (n=275), four fx per week. 4-12 MeV by tumour depth, tumour + 1 cm margin, copper foil to offset skin sparing.
No significant LRF difference between schedules in BCC (p=0.67) or SCC (p=0.46). T stage was the only factor associated with local recurrence (p=0.036); gender, age, histology, indication, site, dose and lesion number were not.
| Group | 54 Gy/18fx | 44 Gy/10fx | p |
|---|---|---|---|
| All tumours | 97.5% | 96.1% | not stated |
| BCC | 97.6% (95% CI 92.7-99.2%) | 96.9% (95% CI 93.1-98.8%) | 0.67 |
| SCC | 97.0% (95% CI 79.1-99.6%) | 93.6% (95% CI 83.4-97.6%) | 0.46 |
| Scorer · rating | 54 Gy | 44 Gy |
|---|---|---|
| Pt · good / fair / poor | 62% / 13% / 25% | 67% / 33% / 0% |
| Observer · good / fair / poor | 38% / 49% / 13% | 33% / 50% / 17% |
Toxicity not reported beyond cosmesis. In a 14-pt pilot, pt-scored good/fair cosmesis was 75% (54 Gy) and 100% (44 Gy), observer-scored 87% and 83%, no significant difference.
The authors cite RT local control of 87-97% for BCC and 56-91% for SCC in prior series, placing these rates at or above that range. They describe them as comparable to surgical series.
Frail pts were moved to 44 Gy before it became standard, which may bias toward fewer recurrences being seen (competing deaths) rather than toward better control. SCC CIs are wide (54 Gy lower bound 79.1%), so equivalence for SCC is not shown.
The authors argue follow-up was adequate because recurrences came early (median 10.4 mo BCC, 3.3 mo SCC). They conclude 44 Gy/10 fx is optimal for T1-T2 disease. The data support non-inferior-looking control at small size, not a formal non-inferiority claim.
Single-centre retrospective; schedule assigned by era and frailty, older 44 Gy cohort with shorter follow-up; univariate only, 15 events total. Cosmesis from 14 pts.
- Is 44 Gy/10 fx adequate for SCC, given wide CIs?
- Late cosmesis and fibrosis after 4.4 Gy fractions beyond 2 years
- Optimal dose for tumours >5 cm
📚 Sources · 📄 1 paper
The longer read
This is a single-institution, era-based comparison of two electron schedules. Its value is less the head-to-head than its documentation of where a ten-fraction course stops working. Overall 3-year actuarial local recurrence-free rates of 97.5% and 96.1% sit at the upper end of the RT ranges the authors cite from prior series (87-97% for BCC, 56-91% for SCC). For BCC treated to 44 Gy, the confidence interval runs from 93.1% to 98.8%, tight enough that a reader can accept the shorter course for small lesions without much worry about giving up control.
SCC is weaker ground. Only 102 SCCs were treated, 33 of them to 54 Gy, and the 54 Gy interval reaches down to 79.1%. A log-rank p of 0.46 in that setting says the study could not see a difference, not that none exists. The pattern of SCC failure also deserves more weight than the headline. Recurrences arrived at a median of 3.3 months, and three of the five came with metastases. That is early, biologically aggressive failure, and the paper does not tie it to dose.
The allocation mechanism is the methodological problem a skeptic will press. 44 Gy was first given to elderly, less mobile pts, so 41.2% of the 44 Gy tumours were in pts over 80, against 17.0% in the 54 Gy group, and follow-up was shorter in the 44 Gy group. In a population whose 3-year OS for SCC was 54%, competing mortality can hide local failures. The competing-risk method handles this in the estimate but cannot recover events in pts who died before failing. So the bias plausibly runs in favour of the hypofractionated arm. The defence, that most recurrences in this series appeared within the first year, is reasonable for BCC and SCC as observed here. It does not settle the comparison.
The T-stage signal is the actionable part. Two of 11 tumours larger than 5 cm recurred, both after 44 Gy, and the centre responded by returning those lesions to 54 Gy. Eleven tumours cannot carry a dose-response conclusion, but they mark the edge of the evidence: the 44 Gy result is a T1-T2 result. The technique details are what make the result reproducible: a 1 cm margin, energy matched to depth, and copper-foil compensation for the electron surface dose. A centre using tighter margins or no surface compensation should not assume the same control rates.
The cosmesis data come from 14 pts photographed at very different intervals (median 66 vs 22 months). They show that the larger fraction size did not produce obviously worse appearance in this small sample, and they say nothing about very late effects of 4.4 Gy fractions. What would make this conclusion wrong is a randomised or matched comparison showing excess late failure or late fibrosis after the shorter course in SCC or larger lesions, which this design cannot exclude.