Established and Validated a Novel Nomogram for Predicting Prognosis of Post-mastectomy pN0-1 Breast Cancer Without Adjuvant Radiotherapy

Abstract

BackgroundThe present study aims to establish and validate a nomogram for predicting prognosis of breast cancer with pN0-1 who are treated with mastectomy and without adjuvant radiotherapy. Material and methods Between Jan 2009 and Dec 2015, a total of 1879 breast cancer without adjuvant radiotherapy were used for nomogram development. The model was externally validated in an independent cohort of 1356 patients from one phase III trial (NCT00041119). The least absolute shrinkage and selection operator (LASSO) regression were performed to identify predictors of breast cancer specific survival (BCSS), local regional recurrence (LRR), and distant metastasis (DM). Results The 5-year BCSS, LRR and DM rates for the entire cohort was 98% ,2% and 4%, respectively. LASSO regression analysis found that pathological T stage, number of positive LN, grade and Ki-67 were significant predictors for both BCSS and DM-free survival in post-mastectomy breast cancer with pN0-1, while number of resected LN and PR status were predictors for DM-free survival. In addition, number of positive LN was the only significant predictor for developing LRR. The C-indexes for the 5-year BCSS and DM nomograms were 0.81 and 0.78 in the training data set, 0.65 and 0.70 in the testing set, and 0.72 and 0.69 in the external validation set, respectively. Calibration plots illustrated excellent agreement between the nomogram predictions and actual observations for 5-year BCSS and DM-free survival.Conclusion Our prognostic nomograms could accurately predict 5-year BCSS and DM-free survival in post-mastectomy early stage breast cancer without adjuvant radiotherapy, which provide a useful tool to identify high-risk patients who could benefit from additional adjuvant therapy.

IMNI PRECISION trial protocol: a phase II, open-label, non-inferior randomized controlled trial of tailoring omission of internal mammary node irradiation for early-stage breast cancer

“…Indeed, multiply studies have been performed to stratify clinical "high risk" early-stage BC patients who might be obtained from adjuvant post-mastectomy radiotherapy (PMRT) [9][10][11][12][13][14]. In consistent with those previous reports, our institution establishes and validates a prognostic nomogram including five risk factors (age, number of positive LN, tumor size, grade and Ki-67) accurately predict 5-year BC specific survival after mastectomy without adjuvant radiotherapy, which provides a practical stratification system to identify "highrisk" BC patients who might be indicated for adjuvant RT [15]. Subsequently, we validate this risk stratification model to individualize the adjuvant RT strategy among pT1-2N1 BC treated with modern systemic therapy, our result indicates that PMRT is an independent prognostic factor for DFS (HR 0.50, p = 0.05) among the clinical "high-risk" patients.…”