ESTRO 2024 - Abstract Book

S1497

Clinical - Lower GI

ESTRO 2024

888

Digital Poster

high rate of organ preservation with Papillon contact x-ray radiotherapy in rectal cancer

Picardi Cristina 1,2 , Caparrotti Francesca 3 , Montemurro Michael 4 , Frédéric Ris 5 , Christen Daniel 6 , Brunner-Schaub Nora 7 , Matzinger Oscar 2 1 Hirslanden Klinik, Radiation Oncology, Zürich, Switzerland. 2 Swiss medical Network, Radiation Oncology, Genolier, Switzerland. 3 Swiss medical Network, Radiation Oncology, Geneva, Switzerland. 4 Swiss medical Network, Medical Oncology, Genolier, Switzerland. 5 Hopitaux universitaires de Geneve, Surgery, Geneva, Switzerland. 6 Swiss medical Network, Surgery, Zürich, Switzerland. 7 Swiss medical Network, Gastroenterology, Zürich, Switzerland

Purpose/Objective:

Rectal cancer typically necessitates a combination of radiotherapy (RT), chemotherapy, and surgery. However, the consequent functional disorders and reduction in quality of life have led to an increasing interest in organ preservation strategies. RT dose escalation would improve the rate of complete responses (CR), but due to the potential toxicity of the surrounding tissues, this strategy remains limited even with modern external beam RT techniques. This study reports on the use of the Papillon, an endocavitary contact RT device, in the treatment of rectal cancer. Papillon delivers low energy X-rays, allowing for significant dose escalation with a favorable toxicity profile

Material/Methods:

Between January 2015 and August 2023, we treated 67 rectal cancer patients with Papillon contact RT in different settings. For this report we assessed the organ-preservation rate and the local control of 23 patients treated with an upfront organ preservation strategy and with a minimum FU of 12 months. Papillon was delivered as a boost to standard RT, with or without chemotherapy. Surgery (TME or local excision) was indicated in case of non response at 3 months or in case of relapse. Follow up was performed according to the major guidelines at a 3 month interval for the first 2 years and every 6 months thereafter.

Results:

All patients achieved a clinical complete response at the first assessment at 6 weeks. After a median FU of 35 months (range 58-12), the organ preservation rate was of 96% (22/23). The local relapse rate was of 8% (2/23). All of our patients were alive at the last assessment. Ten patients achieved long-term (> 3 year) organ preservation. None of our patients developed grade 3 or more acute or late toxicities.

Conclusion:

Our results demonstrate that the addition of Papillon contact RT provides a high rate of local remission with sustained long-term organ preservation and a low toxicity profile. Our results are in line with the recently proffered 3-year results of the OPERA randomized trial. This unique treatment modality may help future patients with rectal cancer benefit from low toxicity RT dose escalation, to achieve complete local response, and avoid surgery. If relapse occurs chance of cure is not compromised.