Background: This study aimed to evaluate the conditional survival (CS) of elderly patients with non-metastatic colon cancer who underwent colectomy and build conditional nomograms that can accommodate varying survival periods and estimate survival rates. Methods: Data from 9302 patients between 2004 and 2017 were obtained from the Surveillance, Epidemiology, and End Results database. CS was used to assess overall survival and colon-specific survival rates in patients who survived beyond a certain time period. Cox regression was used to select factors for nomogram development, and performance was evaluated using area under the receiver operating characteristic curve (AUC), calibration plot, and decision curve analysis (DCA). Results: The 5-year conditional overall survival rates initially increased slightly but then decreased over time. The rates at different time points after diagnosis (baseline and 1-5 years) were 62.5, 63.2, 62.8, 62.1, 61.6, and 59.8%. In contrast, 5-year conditional colon-specific survival rates consistently improved over the same period. These rates were 78.1, 80.9, 84.2, 86.9, 89.3, and 90.9%, respectively. Nomograms were developed for baseline measurements and for patients who survived 1, 3, and 5 years. The performance of these nomograms, assessed using AUC, calibration curves, and DCA, indicated good predictive capabilities. Conclusion: CS provides valuable information on the medium- and long-term survival probabilities of elderly patients with non-metastatic colon cancer who underwent colectomy. The developed conditional nomograms allowed for the estimation of survival probabilities across different timeframes, facilitating a comprehensive understanding of prognosis and collaborative decision making.

The authors have declared no competing interest.

This work was supported by the Project of Chinese Medicine Administration of Jiangsu Provincial Health Commission (MS2021060), Nantong Science and Technology Bureau project (MS2022021), Nantong University Clinical Basic Research Special General Project (2023JQ002), Nantong University Clinical Basic Research Special General Project (2022JY003), the Research project of Nantong Clinical Medical College of Kangda College of Nanjing Medical University (KD2022KYCXTD006, KD2022KYJJZD026), Open Fund for National Key Laboratory of Tumor System Medicine (KF2203-93), and Nantong City Health Commission Research Project (MSZ2022010, MS2023073).

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This investigation used data from the November 2020 release of the Surveillance, Epidemiology, and End Results (SEER) database, obtained specifically from SEER*Stat Version 8.4.2.(https://seer.cancer.gov/seerstat/)

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