Systemic chemotherapy (CT) as salvage treatment for locally advanced rectal cancer (LARC) patients (pts) who fail to respond to neoadjuvant chemoradiotherapy (CRT)

709 Background: International guidelines suggest that RT dose escalation, intraoperative RT or brachytherapy could be considered for LARC pts with positive resection margins, pT4 or unresectable tumours after standard neoadjuvant CRT. However, data to support these approaches are scarce. The potential of systemic CT as salvage treatment after failure of neoadjuvant CRT for LARC has never been explored. We conducted a single-centre, retrospective analysis to address this question. Methods: Pts with newly diagnosed rectal adenocarcinoma who were deemed inoperable or candidates for extensive (i.e. beyond total mesorectal excision, TME) surgery after completion of long-course RT and received salvage systemic CT were included. The primary objective was to estimate the proportion of pts who became potentially suitable for TME after CT. Secondary objectives included the proportion of pts who ultimately underwent TME and survival outcomes. Results: 45 pts (2001-2015) met the study inclusion criteria (39 candidates for extensive surgery and 6 with unresectable tumours). Previous RT was given concurrently with CT in 43 cases (median dose: 54.0 Gy; range: 34.0-55.8). Salvage oxaliplatin-based and irinotecan-based CT was administered in 40 (88.9%) and 5 (11.1%) cases, respectively. 8 pts (17.8%) became suitable for TME based on the MRI after CT, 10 (22.2%) ultimately underwent TME with clear margins and 2 (4.4%) were managed with a watch & wait approach following radiological clinical complete response. Additionally, 13 pts had a beyond-TME surgery with curative intent. 3-year progression-free survival and 5-year overall survival in the entire population were 30.0% (95% CI: 15.0-46.0) and 44.0% (95% CI: 26.0-61.0), respectively. For the curatively resected and watch & wait pts these figures were 52.0% (95% CI: 27.0-73.0) and 67.0% (95% CI: 40.0-84.0), respectively. Conclusions: Systemic CT may be an effective salvage strategy for LARC pts who fail to respond to long-course CRT and are inoperable or candidates for beyond-TME surgery. According to our study, 1 out of 4 pts may become resectable or being spared from an extensive surgery after systemic CT.