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-yearDMrates, using clinicopathological parameters, was successfully developed. This prognostic tool could support decision-making in clinical practice and follow-up strategies.