Mullaney, T G

Surgery remains the cornerstone of rectal cancer treatment. However, there is significant morbidity and mortality associated with pelvic surgery, and the past decade has illustrated that a cohort of rectal cancer patients sustain a remission of local disease with chemoradiation alone. Thus, questions remain regarding the optimal management for rectal cancer; namely, accurately identifying patients who have a complete pathologic response and determining the oncologic safety of the observational approach for this patient group. This review aims to summarize the current evidence to provide an overview to the ‘watch and wait’ approach in rectal cancer patients with a complete response to neoadjuvant chemoradiation therapy.

Abstract Background The prognostic value of pathological lymph node status following neoadjuvant radiotherapy (ypN) remains unclear. This study was designed to determine whether ypN status predicted overall survival. Methods Patients with locally advanced rectal adenocarcinoma who underwent neoadjuvant long-course radiation between 2005 and 2014 were identified from the National Cancer Data Base, and divided into ypN0, ypN1 and ypN2 groups. The primary outcome was overall survival. Univariable and multivariable analyses were used to determine factors associated with overall survival. Results Of 12 271 patients, 3713 (30·3 per cent) were found to have residual nodal positivity. A majority of patients with ypN1 (1663 of 2562) and ypN2 (878 of 1151) disease had suspected lymph node-positive disease before neoadjuvant therapy, compared with 3959 of 8558 with ypN0 tumours (P < 0·001). Moreover, ypN1 and ypN2 were significantly associated with ypT3–4 disease (65·7 and 83·0 per cent respectively versus 39·4 per cent for ypN0; P < 0·001). In unadjusted analyses, survival differed significantly between ypN groups (P < 0·001). Five-year survival rates were 81·6, 71·3 and 55·0 per cent for patients with ypN0, ypN1 and ypN2 disease respectively. After adjustment for confounding variables, ypN1 and ypN2 remained independently associated with overall survival: hazard ratio (HR) 1·61 (95 per cent c.i. 1·46 to 1·77) and 2·63 (2·34 to 2·95) respectively (P < 0·001). Overall survival was significantly longer in patients with ypN1–2 combined with ypT0–2 status than among those with ypT3–4 tumours even with ypN0 status (P = 0·031). Clinical nodal status before neoadjuvant therapy was not significantly associated with overall survival (HR 1·05, 0·97 to 1·13; P = 0·259). Conclusion Both ypT and ypN status is of prognostic significance following neoadjuvant therapy for rectal cancer.