Short-term outcomes of a multicenter randomized phase 2 trial of standard versus reduced-dose chemoradiotherapy for anal cancer

Localized squamous cell carcinoma of the anus (ASCC) is treated with radical chemoradiotherapy. Cure rates are high, but treatment can result in substantial acute and long-term morbidity. The randomized phase 2 PLATO-ACT4 trial, at 28 centers in the UK, compared reduced dose IMRT (41.4 Gy in 23 fractions) versus standard dose IMRT (50.4 Gy in 28 fractions), both with concurrent chemotherapy for early-stage ASCC. Complete clinical response rates at 6 months were good in both groups, with less grade 3 or worse toxicity and better patient-reported outcomes for sexual functioning in the reduced-dose group. The authors conclude that these early results suggest that reduced-dose IMRT with concurrent chemotherapy is well tolerated with oncological outcomes maintained. Three-year locoregional failure rates are awaited.