The Prognostic Benefit of the Histologic Grade for Breast Cancer after Integration into the TNM
DE Henson, D Chen, K Xing, AM Schwartz, L Pham, K Batich, AE Hart. The George Washington University, Washington, DC; Uniform Services University of the Health Sciences, Bethesda, MD
Background: Tumor grade is a prognostic factor for breast cancer, yet it is separately reported and not integrated into staging systems. We hypothesize that incorporation of histologic grade into the TNM would provide added stratification for the staging system.
Design: Data were obtained from NCI's SEER program for years 1990-2000. There were 140,714 cases of breast cancer. Using novel machine learning algorithms based on a censoring cluster analysis, 10 year disease specific overall survival and hazard rates were calculated for certain combinations of tumor size (T), nodal status (N), metastatic status (M), grade (G), and estrogen receptor status (ER). T and N categories were classified according to the AJCC. Survival curves were compared for statistical significance by the log-rank test.
Results: The 10-year relative survival rate for patients with T2, N2, M0 breast cancer is 58%. Integrating ER status and grade into the TNM produces a disease specific survival for ER+ tumors of 73%, 65%, and 53% respectively for grade 1, 2, and 3 tumors. Similarly, for tumors T3, N2, M0, the ten-year relative survival is 44%. Incorporating ER status and grade into the survival analysis produces a disease specific survival for ER+ tumors of 57%, 50%, and 44% respectively for grade 1, 2, and 3 tumors. All differences in rates were statistically significant. In nearly every combination of T, N, and ER, histological grade proved to be a significant prognostic factor. When integrated into the TNM, grades 1, 2, and 3 progressively and significantly reduced the 10 year overall survival and altered the hazard rates regardless of tumor size, nodal status, and ER status. Even with N3 disease, grade still remained a significant prognostic factor.
Conclusions: When integrated into the TNM, grade becomes a significant prognostic factor regardless of tumor size, nodal status, and ER status. The prognostic benefit of grade, and perhaps other prognostic factors, is best demonstrated after integration into the TNM.
Tuesday, March 23, 2010 1:00 PM
Platform Session: Section B, Tuesday Afternoon