Complete response after chemoradiotherapy for rectal cancer: what is the reasonable approach?

Abstract

With the increasing use of preoperative treatment rather than upfront surgery, it has become evident that the response of rectal carcinoma to standard chemoradiotherapy (CRT) shows a great variety that includes histopathologiocally confirmed complete tumor regression in 10-30% of cases. Adaptive strategies to avoid radical surgery, either by local excision or non-operative management, have been proposed in these highly responsive tumors. A growing number of prospective clinical trials and experiences from large databases, such as the European Registration of Cancer Care (EURECCA) watch-and-wait database, or the recent Oncological Outcome after Clinical Complete Response in Patients with Rectal Cancer (OnCoRe) project, will provide more information on its safety and efficacy, and help to select appropriate patients. Future studies will have to establish appropriate inclusion criteria and optimize CRT regimens in order to maximize the number of patients achieving complete response. Standardized re-staging procedures have to be investigated to improve the prediction of a sustained complete response, and long-term close follow-up with thorough documentation of failure patterns and salvage therapies will have to prove the oncological safety of this approach.

Keywords: chemoradiotherapy; complete response; local excision; non-operative management; rectal cancer; wait-and-see strategies.

Figure 1:

The TIMING Trial (Timing of Rectal Cancer Response to Chemoradiotherapy Trial) in locally advanced T3/4 and or N+ rectal cancer patients.

Figure 2:

Trial schema of the MSKCC-based multicenter randomized phase II trial of induction chemotherapy versus consolidation chemotherapy with 5-FU/capecitabine and oxaliplatin before or after chemoradiotherapy in MRI-staged T2-3, N0, or Tany N1-2 rectal cancer (NOM, non operative management; TME, total mesorectal excision).