Natural history and prognostic model of untreated breast cancer: a study based on the SEER database

Abstract Purpose: The primary aim of this study was to explore the natural history of breast cancer in the absence of treatment, aiming to identify the main factors affecting the prognosis of untreated breast cancer patients. Methods: Data for patients diagnosed with invasive breast cancer between 2010 and 2020 were obtained from the SEER database. The disease progression time was estimated by subtracting the median survival time of higher stages from that of lower stages. Untreated patients were divided into a training set and a validation set in a 7:3 ratio. In the training set, independent risk factors affecting prognosis were identified through univariate and multivariate cox proportional hazards regression analysis. A nomogram model was constructed using these risk factors to predict the prognosis of untreated patients, which was then validated in the validation set. Results: In untreated breast cancer patients, the progression time from stage I to stage II was 43 months, from stage II to stage III was 18 months, and from stage III to stage IV was 9 months. Age, tumor stage, ER status, PR status, histological grade, and marital status were identified as independent predictive factors for the overall survival of untreated breast cancer patients, and a nomogram model was constructed with these factors. Conclusion: The disease progression speed of breast cancer patients accelerates with the increase in tumor stage in the absence of treatment, and prognosis progressively worsens. Age, tumor stage, ER status, PR status, histological grade, and marital status are independent risk factors affecting the prognosis of untreated patients.