Clinical nodal staging to assess the risk of local recurrence after rectal cancer resection: A nationwide cross-sectional study.

AIM: In rectal cancer, neo-adjuvant (chemo)radiotherapy (n(C)RT) should be used selectively, due to related toxicity. The decision to offer n(C)RT is mainly based on preoperative MRI staging. cN category has limited accuracy and its use when deciding on n(C)RT is controversial. This population-based study aimed to assess the association between cN category and local recurrence (LR) rate. METHOD: Data from a national cross-sectional cohort of patients who underwent curative resection of primary rectal cancer in the Netherlands in 2016 were used. Patients were subdivided by neo-adjuvant treatment strategy: no n(C)RT, short-course RT with short interval to surgery (SCRT-SI) or downstaging therapy (SCRT with long interval to surgery, CRT, total neoadjuvant therapy or chemotherapy only). The 4-year LR rate was calculated per (y)cN category and corrected for known pre-operative confounders in Cox-regression analysis. RESULTS: Of 2148 included patients, 1000 received no n(C)RT, 449 SCRT-SI and 699 downstaging therapy. Median follow-up was 50 months (interquartile range [IQR] 38-55). The 4-year LR rates for cN0, cN1 and cN2 were 6.3%, 5.0% and 6.2% without n(C)RT, and 0%, 2.4% and 0% after SCRT-SI. In patients treated with downstaging therapy, not primary cN, but restaging ycN category was significantly associated with LR rate (9.1%, 17.4% and 18.5%; p = 0.006) in univariable analysis. In multivariable analysis, no association was observed between ycN and LR (p = 0.088). CONCLUSION: Evaluation of nationwide clinical practice did not reveal significant associations between cN category and LR rate after rectal cancer resection within three neo-adjuvant treatment groups, which questions its validity for clinical decision-making.