onc brain

The longer read

This series does what most single-center skin brachytherapy reports do. It shows that a CT-planned, custom mould HDR approach can be delivered to a very old, comorbid population without grade 3 toxicity, and that early response is near universal. What it cannot show is long-term local control. The headline 2-yr LC of 84.9% is an actuarial projection from a cohort followed for a median of 8 months, in which a third of pts died, mostly of unrelated causes. With that much censoring, the 2-yr figure should be read as a statement about the first year rather than a durable control estimate, and the late toxicity profile, including the single grade 2 necrosis appearing around month 10, is almost certainly incomplete.

Against the comparators the authors cite, the result is plausible but not reassuring on its own terms. They frame their LC as consistent with brachytherapy reports ranging from 83.3% to 100% and EBRT reports of 87-100%, while Mohs sits at 95-99%. Their figure falls at the bottom of each range. The Gauden series they lean on reported LC 98% with 36 Gy/12 fx, but at a comparably short follow-up and in a setting dominated by post-resection margin-positive disease, which is a more favorable target than gross tumor in an elderly pt. Cross-series comparison here is weak in both directions, and the authors acknowledge that this literature is small and retrospective, which is why GEC-ESTRO grades the technique B.

The more useful content for a planning radiation oncologist is the dosimetry. Prescribing at 0.5 cm with no PTV margin and a 90% coverage intent produced a median V100 of 73.7% and V90 of 92.3%, with a surface dose of 126.5%. The univariate split, LC 88.9% when V90 exceeded 95% vs 76.9% below, points in the direction one would expect, and the same is true for median target dose above vs below 100%. None of these reached significance, and with five local recurrences the analysis had essentially no power, so the right reading is that coverage may matter and this dataset cannot tell how much. Whether a modest CTV-to-PTV margin, which the authors note is controversial in brachytherapy, would close that gap is the practical question the data raise.

The histology split cuts against expectation: BCC LC 70% vs SCC 88.2%, with three of the five recurrences being nasal BCC. That is more likely a small-numbers artifact or a reflection of nasal geometry and mould conformity than a biologic signal, but it is a reason not to assume BCC is the easy case for this technique on the nose.

The decision this informs is narrow. For a frail pt with a superficial head-and-neck BCC or SCC who is not a Mohs candidate, surface mould HDR is a tolerable, non-invasive option with high early response. It does not establish equivalence with surgery or EBRT, and it says nothing about lesions deeper than 5 mm. Pooled histologies, mixed intent and visible internal inconsistencies in the reported demographics and follow-up should temper how much weight any single number carries.