KEY POINTS
- This single-centre retrospective study included 49 patients with 50 lesions unsuitable for conventional superficial treatment. Median age was 78.6 years; 37 lesions were BCC and 13 SCC, while 22/50 were recurrent after prior surgery.
- Disease was often anatomically challenging: 44% of lesions were T3, and the most common locations were the periorbital region (42%) and external nose (22%).
- Pure interstitial brachytherapy was used in 35 lesions (70%), while 15 (30%) received a hybrid interstitial plus surface-applicator approach. HDR was used in 30 lesions and PDR in 20.
- HDR schedules delivered 40–45 Gy in 8–13 twice-daily fractions. PDR delivered 42.5–60 Gy using hourly 0.5–0.6-Gy pulses over 4–5 days. Median CTV V100 was 96.5%.
- At a median follow-up of 21.2 months, crude local control was 94%, with only three local failures; estimated 2-year local control was 93.6%. Control was similar for BCC versus SCC (94.6% vs 92.3%) and PDR versus HDR (95.0% vs 93.3%).
- Early tissue reactions were substantial: 26.5% had grade 3 and 14.3% grade 4 acute reactions, mainly prolonged healing or tumor-bed necrosis. The authors caution that early necrosis after definitive treatment of infiltrative skin cancers may not behave like conventional toxicity scoring.
- Late grade 3 toxicity occurred in 2% and grade 4 in 6%, with grade 4 events representing chronic ulceration requiring wound care. Higher T stage was the only significant predictor of grade ≥2 late toxicity (p=0.044); HDR versus PDR was not (p=0.28).
CLINICAL TAKEAWAY
Interstitial or hybrid brachytherapy can provide high local control when superficial RT or surgery is poorly suited to deep, recurrent or anatomically difficult NMSC. The trade-off is meaningful tissue toxicity in more advanced lesions, and the study is not large enough to establish equivalence between HDR and PDR approaches.