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The paradigm of early stage rectal cancer treatment is rapidly changing with attempts to avoid unnecessary surgery. Radiotherapy (RT) with chemotherapy (RCT) play a major role in terms of local control (LC). 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. We report our institutional short-term outcome of patients treated with endocavitary low energy contact RT, better known as Papillon.

Between 2015 and 2022, we used Papillon to treat 50 rectal cancer patients; however, for the purpose of this report, we excluded patients treated with Papillon after neo-adjuvant RCT, in a salvage setting after local relapse, and as an adjuvant treatment of a malignant polyp,

We treated 23 patients in our institution with Papillon after external beam RT or RCT with the intent to achieve a pre-planned organ preservation strategy. We report the outcome of 20 patients with > 3 months follow-up (FU). Toxicities were systematically reported.  Papillon was commonly delivered in 3 fractions (median; range, 1-4), and the most common prescribed dose was 90 Gy (range, 40 – 90).

Median FU was 26 months (range, 4-48). Median age was 70 years (range, 49-91). Nine patients had Stage I (T1-T2N0), 6 patients stage II (T3N0), 4 patients stage III (T1-3N0-N2), and 1 patient stage IV (T3N0M1). Response to treatment was evaluated at 6 weeks (digital examination, DRE) and at 3 months (MRI, rectoscopy, DRE). FU with MRI, DRE, rectoscopy, and endosonography (when judged necessary), was performed every 3 months for the first 2 years and every 6 months thereafter. A thoracic and abdominal CT scan was performed every 6 months.

All of our patients had a complete clinical response at their 3 months assessment. Biopsies were taken in 3 patients with dubious lesions, confirming no residual disease. So far, 7 patients achieved long term (> 3 years) organ preservation. Acute toxicity was very mild with most patients experiencing erratic bowel movements within the first 3 months. G1 rectitis was the most common late effect (n= 4), except for one patient who needed argon cauterization (G2). There were no treatment related deaths.

Our experience with Papillon x-ray contact radiotherapy shows in our selected patients a complete local response achieving long-term organ preservation. 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 early stage rectal cancer benefit from low toxicity RT dose escalation, to achieve complete local response, and avoid surgery.