Interstitial PDR brachytherapy for the treatment of squamous cell anal carcinoma
PO-1105
Abstract
Interstitial PDR brachytherapy for the treatment of squamous cell anal carcinoma
Authors: BOURDAIS|, Remi(1)*[bourdais.radiotherapie@gmail.com];Achkar|, Samir(1);Kumar|, Tamizhanban(1);Kissel|, Manon(1);Ta|, Minh Hanh(1);Pounou Kamga|, Franck Arthur(1);Boukhelif|, Wassila(2);Durand-Labrunie|, Jérôme(1);Haie-Meder|, Christine(1);Chargari|, Cyrus(1);
(1)Gustave Roussy, Radiothérapie, Villejuif, France;(2)Centre Hospitalier Intercommunal de Créteil, Radiothérapie, Créteil, France;
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Purpose or Objective
To examine the outcome of patients treated with interstitial pulsed-dose-rate brachytherapy (PDR-BT) for boosting the residual tumor after external radiotherapy for an anal squamous cell carcinoma.
Material and Methods
Medical records of patients receiving a brachytherapy boost after radiotherapy for squamous cell anal carcinoma in our Institute between 2008 and 2019 were retrospectively reviewed. After receiving pelvic irradiation +/- concurrent chemotherapy, patients were delivered a PDR-BT boost to the residual tumor, with intention to deliver a minimal total dose of 60 Gy. Brachytherapy implantation was performed according to the Paris system, only one plane implant being used. Patients outcome was examined with focus on local control and morbidity.
Results
A total of 42 patients were identified: 24, 13, and 5 with stages I, II, and III tumors, respectively. The greatest dimension of residual tumor at the time of brachytherapy procedure was 8.8 mm (range: 0-30 mm). Median BT dose was 20 Gy (range: 10-30 Gy), delivered through a median number of 48 hourly pulses (range: 20-80 pulses). Median dose per pulse was 42 cGy (range: 37.5-50 cGy). Median treated volume was 9.7 cm3 (range: 4.5-34.28 cm3). Median over dosage volume (V200%) was 1.7cm3 (range 0.4-7.3 cm3). The median number of implanted needles was 3 (range: 2–4). With median follow-up of 60.4 months (range: 5.4-127.4 months), a total of five patients (12%) experienced tumor relapse, including local relapse in three patients (7.1%). Thirty-eight (90%) were alive at last follow-up. No Grade 3 or more acute toxicity was reported. Out of 40 patients with more than 6 months follow-up, only one patient experienced grade 3+ delayed toxicity (fecal incontinence). None patient required surgery for toxicity.
Conclusion
With almost 5 years median follow-up, this study confirms that an approach based on PDR-BT treating the tumor residuum is effective and safe in this indication for selected patients with mainly Stage I tumors. Local control rate and toxicity were in the range of what was seen with continuous low-dose-rate brachytherapy. Morbidity profile was favorable, possibly as a consequence of patient selection and technique used.