The ultimate local failure rate after the watch-and-wait strategy for rectal cancer: a systematic review of literature and meta-analysis

BackgroundWe hypothesise that a high rate of tumour regrowth after the watch-and-wait (w & w) strategy may lead, despite salvage surgery, to a significant impairment of ultimate local control compared with immediate surgery.Materials and methodsTo test this hypothesis, we conducted meta-analyses of studies on the w & w strategy (both opportunistic and planned) with an ultimate local failure rate as an endpoint in three patient groups: (1) in all starting radio(chemo)therapy as potential w & w candidates, (2) in a subgroup starting w & w, and (3) in a subgroup with regrowth.ResultsWe identified eight studies for evaluation of local failure in group 1 (N = 837) and 36 studies in group 2 (N = 1914) and in group 3 (N = 439). The meta-analysis revealed an ultimate local failure rate of 8.0% (95% CI 4.8%-12.1%) in group 1 and 5.4% (95% CI 3.9%-7.1) in group 2. These rates are similar to those reported in the literature following preoperative chemoradiation and surgery. However, in the most unfavourable group 3 (with regrowth), the rate of ultimate local failure was 24.1% (95% CI 17.9%-30.9%), with the most common causes being patients' refusal of salvage total mesorectal excision (TME) (9.1%), recurrence after salvage TME (7.8%), distant metastases (4.1%), frailty (2.4%), and pelvic tumour unresectability (1.7%).ConclusionNearly 25% of patients with regrowth (unfavourable subgroup) experienced ultimate local failure, primarily due to refusing salvage TME. The risk of ultimate local failure in patients initiating radio(chemo)therapy as potential w & w candidates, or in patients starting w & w, appears comparable to that reported after preoperative chemoradiation and surgery. However, this comparison may be biased, because w & w studies included more early tumours compared with surgical studies.