Background: Occult breast cancer is a rare breast tumor, whose prognostic nomogram model has not been established. Thus, we aim to develop and validate a nomogram for evaluating the overall survival (OS) and cancer-specific survival (CSS) of patients with occult breast cancer.
Methods: Between 2004 and 2015, 704 eligible occult breast cancer patients were screened from the Surveillance, Epidemiology, and End Results (SEER) database using specific inclusion and exclusion criteria and then included in the surveillance. They were randomly divided into a training cohort (n = 494) and a validation cohort (N = 210). Univariate and multivariate Cox analyses were performed to explore independent prognostic factors and establish two survival-related nomograms. Area under the curve (AUC), consistency index (C index), internal and external validation calibration curve, decision curve analysis (DCA), Kaplan-Meier analysis, and subgroup analysis were used to evaluate the nomogram.
Results: A total of seven variables were considered to be independent prognostic factors for overall survival (OS) and cancer-specific survival (CSS): age, chemotherapy, radiotherapy, Progesterone receptor (PR) status, N stage, number of lymph node examinations, and number of positive lymph nodes. In the training cohort, the OS nomogram-predicted AUC for three, five, and ten years were 0.792, 0.775, and 0.783, respectively, while those of the CSS nomogram were 0.807, 0.817, and 0.812, respectively. The calibration chart showed excellent agreement between the actual and the nomogram-predicted survival rates in both the training and validation cohorts. The C-index values of the OS nomogram in the training and validation cohorts were 0.762 and 0.782, respectively, while those of the CSS nomogram were 0.786 and 0.816, respectively. DCA and subgroup analysis proved the usefulness of nomograms.
Conclusion: The developed nomogram provided a comprehensive visual model of the risk of each prognostic factor. It can be conveniently used as a personalized prediction tool for the prognosis of occult breast cancer patients.