Prognostic Analysis of Neoadjuvant versus Adjuvant Chemotherapy for Stage III Rectal Cancer with Tumor Deposit-Positive Via the SEER Database

Purpose The study developed a prognostic nomogram to predict survival in stage III rectal cancer patients with tumor deposits receiving neoadjuvant versus adjuvant chemotherapy, guiding perioperative treatment decisions. Methods The study included 3,060 stage III rectal cancer patients with tumor deposits from the SEER database (2010–2017). Propensity score matching (1:1 PSM) addressed treatment bias. The adjuvant chemotherapy cohort (n = 1,520) was divided into training (n = 1,064) and validation (n = 456) sets at a 7:3 ratio. Multivariable Cox regression analysis identified prognostic factors for nomogram construction. Model performance was assessed via C-index, AUC, and calibration curves. Patients were classified as high-risk and low-risk groups based on the nomogram scores. KM curves were used to compare the survival differences between the two patient categories. Results In a cohort of 2,289 patients with stage III rectal cancer with positive tumor deposits, the Kaplan-Meier analysis demonstrated that adjuvant chemotherapy significantly improved overall survival compared to neoadjuvant chemotherapy. A nomogram incorporating age, grade, serum CEA, and perineural invasion predicted survival in adjuvant chemotherapy patients, with low-risk patients exhibiting superior survival benefits. Conclusion The nomogram was constructed to successfully predict the 1-, 3- and 5-year OS for patients who received adjuvant chemotherapy. In addition, this nomogram may assist in developing clinical treatment strategies for patients with tumor deposits who are undergoing treatment.