Accuracy of a nomogram to predict the survival benefit of surgical axillary staging in T1 breast cancer patients.

T1 breast cancer patients have favorable clinical outcomes, so that whether axillary stating (AS) surgery can be omitted in these patients is still unclear. This retrospective cohort study developed a nomogram to predict the cancer-specific survival (CSS) of T1 breast cancer patients with and without AS and estimate the survival benefit of AS in these patients.We used surveillance, epidemiology, and end results (SEER) database to identify 232,195 breast cancer patients with T1 tumors diagnosed between 1990 and 2008. In the training cohort, we used the Kaplan-Meier method and the competing risk analysis, with non-CSS as the competing risk, to screen for prognostic factors for CSS. A nomogram to predict the CSS, with receiving AS or not as one of the predictors, was developed and externally validated, using the C-index and calibration plots. The survival benefit of AS can be estimated by the difference of 2 predicted CSS, when the patient was considered as having and not having AS.With a median follow-up of 109 months, the CSS of the study population were 96.3%, 92.3%, and 88.5% at 5, 10, and 15 years, respectively. Significant predictors for CSS identified in the training cohort were used to develop a nomogram, which was validated internally [C-index = 0.707, 95% confidence interval (95% CI) 0.702-0.712] and externally (C-index = 0.704, 95% CI 0.698-0.710). The nomogram was well calibrated. With this nomogram, AS was predicted to have less than 2% benefit of 5-, 10-, and 15-year CSS in 60.6% (140,599/232,195), 15.5% (36,074/232,195), and 8.6% (20,043/232,195) of the entire study population, respectively.The new nomogram can accurately predict the CSS of T1 breast cancer patients, and also be able to estimate the survival benefit of AS in these patients. Prospective studies are needed to confirm our findings.