'Folfirinox' chemotherapy combined with contact x-ray brachytherapy 50kVp and 'CAP50' chemoradiotherapy aiming at organ preservation for selected intermediate distal-middle cT2-T3 rectal cancers: A feasibility study.

ABSTRACT

PURPOSE: The standard treatment of T2-T3 rectal adenocarcinoma is radical proctectomy by total mesorectal excision often combined with some neoadjuvant treatment. To reduce morbidity of this surgery, organ preservation strategy using various combination of radiotherapy, chemotherapy and local excision is gaining interest. Some randomized trials have proven the feasibility of such approaches. The OPERA trial demonstrated, for T2 T3<5cm diameter low-middle rectum, that a contact X-ray brachytherapy boost of 90Gy in three fractions over 4 weeks was able to achieve a planned organ preservation in 81% of patients at 3years with 97% success for tumour smaller than 3cm treated with contact X-ray brachytherapy boost first. To try to expand organ preservation to larger tumours we set up a feasibility trial in T2-T3 tumours using total neoadjuvant treatment and a contact X-ray brachytherapy boost. MATERIAL AND METHOD: The trial was approved by the institutional review board of Nice. Inclusion criteria were operable patients, 75years or less, adenocarcinoma of the low-middle rectum staged T2c-T3N0 larger than 3.5cm and less than 6cm in diameter or T2-T3N1 less than 6cm in diameter. Treatment started in all cases with neoadjuvant chemotherapy associating 5-fluoro-uracile, irinotecan and oxaliplatin ('folfirinox' regimen, four to six cycles). In case of good tumour response after four cycles, a contact X-ray brachytherapy boost (delivering 90Gy in three fractions) was given followed by chemoradiotherapy (external beam radiotherapy delivering 50Gy, with concurrent capecitabine). After six cycles if only a partial response (tumour still larger than 3cm) was seen, chemoradiotherapy was given and contact X-ray brachytherapy boost was delivered after that. At the end of this total neoadjuvant treatment a watch and wait strategy was decided in case of clinical complete response or radical proctectomy by total mesorectal excision for partial response. RESULTS: Between July 2019 and October 2022, 14 patients were included; median age was 66years (range 51-77years), there were nine male and five female, two T2 N1 tumours, seven T3N0, and five T3N1, all were M0. Median tumour diameter was 40mm (range 11-50mm); three tumours had a circumferential extension greater than 50%. Seven patients received four folfirinox cycles and seven had six cycles. Contact X-ray brachytherapy boost was given during folfirinox chemotherapy before chemoradiotherapy in 11 patients (and after in three). The tolerance was good, with no grade 4-5 toxicity. The main grade 3 early toxicity was in relation with the folfirinox regimen. A clinical complete response was seen in 12 patients at the end of the total neoadjuvant treatment (85%). All these patients are alive and have preserved their rectum with a mean follow-up time of 17.8months (range 6-48months) and a good bowel function (low anterior rectal resection syndrome score below 30). The main contact X-ray brachytherapy boost toxicity was radiation ulceration in three patients that usually healed within 6 months, sometimes necessitating hyperbaric oxygen. CONCLUSION: The preliminary results of this feasibility study show that early tolerance of these intensive total neoadjuvant treatment is compatible with an acceptable toxicity. The high rate of organ preservation in this intermediate group of T2-T3 tumours is encouraging and is a good argument to start the next randomized TRESOR trial that will aim at achieving a 65% of 3-year survival with organ preservation in this intermediate tumour group.