Endorectal HDR brachytherapy produced 80% initial response in frail rectal cancer

KEY POINTS

• This single-institution series included 15 elderly or frail patients with T1–3 N0–1 M0 rectal adenocarcinoma who were unsuitable for or declined radical surgery. Median age was 83 years, and 80% had ECOG 1–2.
• Treatment combined short-course VMAT with endorectal dose escalation. EBRT delivered 30–39 Gy in 10–13 fractions, followed by image-guided HDR brachytherapy of 12–24 Gy in 2–3 fractions, generally delivered as 6–8 Gy weekly fractions prescribed 5–10 mm deep.
• Dose was progressively escalated across the cohort. Median combined prescription-depth EQD2₁₀ was 66.3 Gy, while the median PTV-level cumulative EQD2₁₀ was approximately 83 Gy; median HDR-BT PTV D90 was 103.5% and V100 93.4%.
• At the first response assessment, 12/15 patients (80%) achieved clinical complete or near-complete response: 6 cCR and 6 ncCR. Three patients had an incomplete response.
• Among patients with an initial cCR/ncCR, 4 developed local regrowth during follow-up. Distant metastases occurred in 4/15 patients (27%), including two with incomplete response and two initial responders. Median follow-up was 21 months.
• Acute toxicity was generally modest, with no grade ≥3 acute events. Grade 1–2 proctitis occurred in 67% after EBRT, while acute toxicity from the brachytherapy component was limited mainly to grade 1 proctitis.
• Late toxicity was the major concern: 4/15 patients (27%) developed grade 3 events. Three had rectal bleeding requiring transfusion and one developed rectal ulceration with necrosis requiring rectal amputation; 2 of the 3 patients with grade 3 bleeding were receiving oral anticoagulation.

CLINICAL TAKEAWAY

SOURCE

Strahlentherapie und Onkologie