A nomogram to predict distant metastasis after neoadjuvant chemoradiotherapy and radical surgery in patients with locally advanced rectal cancer

PURPOSE To compare distant metastasis (DM) in locally advanced rectal cancer (LARC) patients treated with neoadjuvant chemoradiotherapy (nCRT) and surgery alone, and to develop a predictive nomogram for DM following nCRT. METHODS Propensity‐scoring match analysis was performed to compare DM in LARC treated with nCRT ( n = 375) and surgery alone ( n = 375). Cox regression was performed to identify predictors of DM following nCRT. A nomogram was developed and validated by internal ( n = 425) and external validation ( n = 97). RESULTS The 5‐year local recurrence rate was significantly lower in the nCRT group (5.6% vs. 10.4%; P = 0.020). The 5‐year DM rates (nCRT vs. surgery alone: 25.3% vs. 24.4%; P = 0.235) were similar between groups. Cox regression showed that the post‐nCRT pathologic stage (ypTNM stage, OR = 2.022, P = 0.002), IMA nodal metastasis ( OR = 2.171, P = 0.023), and CRM involvement ( OR = 2.535, P = 0.016) were independently associated with DM following nCRT. A predictive nomogram was developed with a C‐index of 0.70 on internal validation, and 0.71 on the external validation. CONCLUSION NCRT improved local control, but not distant metastasis. A nomogram to predict 3‐ and 5‐year DM rates, using clinicopathological parameters, was successfully developed. This prognostic tool could support decision‐making in clinical practice and follow‐up strategies.