KEY POINTS
- Single-center retrospective study of 84 patients with localized or locally advanced anal squamous cell carcinoma treated with volumetric modulated arc therapy from June 2019 to July 2024.
- 50 patients received simultaneous integrated boost radiotherapy and 34 received a sequential boost approach; all patients received 60 Gy in 30 fractions to the primary tumor and involved lymph nodes.
- Elective nodal irradiation was delivered as 44 Gy in 22 fractions in the sequential group or 45 Gy in 30 fractions with simultaneous integrated boost.
- Two-year disease-free survival was 96% with simultaneous integrated boost versus 70% with sequential treatment; simultaneous integrated boost remained independently associated with improved disease-free survival in multivariable analysis (hazard ratio 0.16, 95% confidence interval 0.03-0.75, p = 0.020).
- No acute or late grade >3 skin, gastrointestinal, or urinary treatment-related adverse event was observed. Post-treatment lymphocyte counts were higher in the simultaneous integrated boost group (0.82 versus 0.68 G/L, p = 0.029).
CLINICAL TAKEAWAY
This study supports simultaneous integrated boost as a relevant modern delivery strategy for anal cancer chemoradiotherapy, with better disease-free survival and no clear toxicity penalty in this cohort. The result is clinically interesting, but not definitive: the study was retrospective, single-center, non-randomized, and the simultaneous integrated boost group had shorter follow-up. Residual temporal and biological confounding cannot be excluded.