538P - Planned organ preservation for T2 T3 M0 rectal adenocarcinoma: A possible option using chemoradiotherapy (CRT) and contact X-ray brachytherapy (CXB). A French multicenter study

Abstract

BackgroundStandard treatment for T2-3 M0 rectal adenocarcinoma is rectal resection (TME) often combined with neoadjuvant CRT. If a clinical complete response (cCR) is achieved a “watch and wait” (or local excision) is a possible option to improve quality of life. The Lyon R96-02 phase III trial has demonstrated that adding a CXB boost to CRT was able to increase safely the chance of cCR (1). Since the manufacture in 2010 of the PapillonTM CXB machine, this strategy has seen a renaissance. MethodsBetween 2003 and 2016, 74 patients M0 have been treated in 3 French centres (Lyon, Mâcon, Nice). Median age was 74 years. Classification was done using MRI and/or Endorectal ultrasound. T2: 45, T3: 29. CRT was: CAP 50 (capecitabine: 800mg/m2 BID + RT: 50Gy/ 25 fr/5 weeks). CXB delivered a local boost of 90-110Gy in3-4 fractions over 4-6 weeks either before or after CRT. The boost was given first if T<3.5cm in diameter. Close surveillance was every 3 months using Digital rectal examination, endoscopy and MRI. ResultsOut of 74 patients with a median follow-up time of 40 months, the cCR rate at 6 months (after treatment initiation) was 95%. The 3-year local recurrence rate and specific cancer survival were respectively 10% and 88%. Organ preservation was seen in 95% with a good bowel function in 90% of cases. Among 6 patients with local recurrence none was seen for polypoid T2T3a < 3.5cm in diameter. For tumor treated using CXB first (42 pts) a cCR was observed at week 4 in 67% and at 3 month in 95% of cases (vs 75% at 3 months for CXB given after CRT) (2). ConclusionsA possible option for T2 T3 a-b < 5cm is organ preservation combining CRT and CXB. For polypoid lesions < 3.5cm treated using CXB first the chance of cCR at 3 months and long term rectal preservation are above 85%. In such selected patients, a “planned” organ preservation can be proposed from the start as it is presently for SCC anal canal tumors. The ongoing OPERA phase III trial is testing this proposal.