The Effect of Clinical (Anatomical) and Prognostic Stage Groups on Survival in Patients Diagnosed with Breast Cancer: MULTI-Center Study Results, TROD Breast Cancer Study Group

Abstract

The American Joint Committee on Cancer (AJCC) anatomic stage groups have arguably been the most powerful method in predicting breast cancer outcomes. In the present study, we aimed to determine the differences between anatomical stage and clinical prognostic stage groups, which were obtained by adding biological markers such as histologic tumor grade, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 status to patients diagnosed with breast cancer, the rate of change in stage, and the effect of stage change on survival. The study protocol was sent to all radiation oncology centers in Türkiye. Four centers enrolled their patients to the study. A total of 1470 stage I-III breast cancer patients with complete information on biological markers (histologic tumor grade, hormone receptor, and c-erb B2 receptor status), haven't been treated with neoadjuvant therapy were included to the study and evaluated retrospectively. The 8th edition of AJCC consolidated biological markers in to clinical prognostic stage groups. Kaplan-Meier curves were used to estimate survival. The log-rank test was used to compare the difference between groups. The Cox proportional-hazards regression model was used to determine the association between anatomic-prognostic stage, disease-free survival (DFS), and overall survival (OS). The median follow-up time was 82 (6-237) months. Median age of the patients was 52 years (20-88) and 865 cases (58.8%) were in the postmenopausal period. The axillary lymph node status was negative (N0) in 765 patients (52.1%). Tumor grade was grade I in 200 patients (13.6%), grade II in 812 patients (55.2%) and grade III in 452 patients (30.7%). Estrogen receptor status was positive in 1247 patients (84.8%), PR status was positive in 1178 patients and Her2-neu status was positive in 207 patients (14.1%). A stage change has been identified in a total of 777 patients (52.9%). Compared with the anatomic stage groups, application of the clinical prognostic stage groups assigned 46.4% cases lower and 6.5% cases higher stage. Five- and ten-year OS and DFS rates of the patients are 73.7%, 44.3% and 91.9%, 86.3% respectively. Age (p<0.001), tumor grade (p<0.001), ER status (p<0.001), PR status (p<0.001), cerbB2 receptor status (p = 0.025) were found to be statistically significant variables in multivariable analysis for OS. For DFS, multivariable analysis showed that age (p = 0.027), tumor grade (p = 0.005), anatomical stage (p<0.001) and assigned to higher stage (p = .001) were statistically significant variables. Hormone receptors and c-erb B2 receptor status are independent variables which impact OS and DFS in our patient group which is mostly consisted of early-stage cases according to anatomical stage. In prognostic staging, upstaging stands out as an independent prognostic factor for DFS. The 8th edition of AJCC prognostic stage groups determines the prognosis much better in our patient cohort.