Radiotherapy for epithelial skin cancer (Locke)
ForCutaneous BCC/SCC, untreated or recurrent, definitive RT
TL;DRLocal control 89% overall (93% untreated vs 80% recurrent) across 531 BCC/SCC lesions; dose/fx <2 Gy predicted local failure (p=0.01).
The dose-per-fraction signal is confined to BCC 1.1-5 cm: 75% LC at ≤2 Gy/fx vs 95-100% at larger fx sizes (p=0.01), with no equivalent effect for SCC. Recurrent SCC is the weak group (68% LC, 32% nodal involvement), which bears on whether a recurrent SCC field should be treated more aggressively than a primary.
In a 1-5 cm BCC planned for definitive RT, this series argues against conventional ≤2 Gy fractions; it says nothing about fraction size for SCC, where no dose response was seen.
For BCC 1.1-5 cm, ≤2 Gy/fx gave 75% LC vs 95-100% with larger fractions (p=0.01), with no such effect in SCC. Modality dropped out on multivariate analysis (p=0.345) once electron margins widened, so margin and fraction size matter more than beam choice.
16 details
Single-institution retrospective review of consecutive pts treated 1966-1997. 468 pts, 531 lesions; median f/u 5.8 yr (range 2-24).
Biopsy-proven epithelial skin cancer: 389 BCC, 142 SCC; 364 previously untreated, 167 recurrent. Median age 73 (BCC) and 72 (SCC).
Superficial x-rays 60%, electrons 19%, electrons + superficial 20%, megavoltage photons <2%. Volume was tumor plus microscopic extension, with an additional 1 cm margin depending on size; lead eye shields when near the eye, and bolus use evolved over time.
Local control (relapse-free from RT start), cosmesis (telangiectasia, pigment change, fibrosis) and complications.
Overall LC 89%; untreated 93% vs recurrent 80%. On multivariate analysis, fraction size (p=0.01), lesion diameter and histology (p<0.01) predicted local failure; modality did not (p=0.345).
| Group | Local control |
|---|---|
| All lesions | 89% |
| Previously untreated | 93% (338 of 364) |
| Recurrent | 80% (133 of 167) |
| BCC overall | 92% (358 of 389) |
| SCC overall | 80% (113 of 142) |
| BCC recurrent | 86% (90 of 104) |
| SCC recurrent | 68% (43 of 63) |
| Dose/fx (Gy) | Local control |
|---|---|
| ≤2 | 38/51 (75) |
| 2.01-3 | 89/94 (95) |
| 3.01-4 | 10/10 (100) |
| >4 | 19/19 (100) |
Complications 5.8% overall (13% for lesions >5 cm), mainly soft-tissue necrosis: 9% of SCC vs 2% of BCC. Fair/poor cosmesis was 4% with superficial RT vs 12% electrons and 19% combination.
The same institution's 1986 series (Lovett et al.) found electrons worse on multivariate analysis. Here that association disappears, which the authors attribute to wider electron margins in later years. The <2 Gy/fx failure signal matches Silva et al. in pinna lesions.
Treatment spans three decades with evolving bolus and margin policy. The cosmesis data are missing for 15-25% of untreated lesions, and the SCC dose cells are small, so the absent SCC dose response may reflect low power.
The data support RT as definitive therapy for early BCC/SCC and put the main lever on fraction size and lesion size, not beam type. Recurrent SCC carries the poorest control and the most cosmetic cost, so failure at first treatment is expensive.
Retrospective single-institution series spanning three decades; modality chosen by lesion size, not randomized, so dose and modality associations are confounded. No surgical comparator.
- Optimal hypofractionation schedule for cutaneous SCC
- Elective nodal coverage for recurrent cutaneous SCC
- Do modern electron margins and bolus close the gap with superficial RT?
📚 Sources · 📄 1 paper
The longer read
The most useful read of this series is the fractionation finding, and it is narrower than the headline suggests. For BCC 1.1 to 5 cm, local control was 75% at 2 Gy or less per fraction against 95 to 100% at larger fraction sizes, and fraction size survived multivariate analysis (p=0.01). That fits the long clinical habit of hypofractionating cutaneous BCC and the result reported by Silva et al. for pinna lesions. But the effect sits in one histology and one size band. For SCC the authors found no clear dose response and no significant fraction-size difference, and the per-cell counts are small enough that this should be read as absence of evidence, not evidence of absence. A reader should not extend the BCC fractionation argument to SCC on the strength of this paper.
The modality comparison needs more caution than the crude numbers invite. Superficial x-rays controlled 94% of lesions against 82% for electrons and for combination treatment, which looks like a clear gradient until you remember how beams were assigned. Electrons went to larger and deeper lesions, and size was itself an independent predictor of failure. Once diameter, histology and fraction size were in the model, modality fell away (p=0.345). The authors make an interesting internal comparison: their own 1986 series had found electrons worse on multivariate analysis, and they attribute the change to wider electron margins in later years. That is plausible and clinically relevant, since electron penumbra at the skin surface is the classic way to underdose a lateral edge, but it is an explanation offered after the fact rather than something the design can test. The margin tables point the same way for SCC with 1 cm or smaller electron margins, without reaching significance.
The recurrent-disease data carry the most practical weight. Recurrent SCC had 68% local control and 32% nodal involvement, compared with 89% and 14% for untreated SCC, and recurrent SCC also had the worst cosmesis. One third of the cohort had already failed a prior treatment, so this is not a rare scenario. The finding argues that the first treatment of a cutaneous SCC is where control is won or lost, whatever modality is used, and that a recurrent lesion should be staged and managed as higher-risk disease, nodal basin included.
The main reasons for caution are structural. The series spans 1966 to 1997, with bolus and margin policy changing along the way. Cosmesis was graded retrospectively from notes and photographs and is missing for a meaningful fraction of lesions. There is no surgical or Mohs comparator, so the paper says nothing about whether RT should be chosen over excision. What it can support is that, when RT is chosen, lesion size, histology and fraction size drive control far more than beam choice.