Risk factors for local recurrence after breast-conserving therapy for invasive carcinomas: A case-control study of histological factors and alterations in oncogene expression

Purpose: Many studies have focused on histological risk factors for local recurrence (LR) after breast-conserving therapy (BCT), In addition to histological factors, we studied alterations in the expression of various proteins in relation to LR using a case-control approach. Methods and Materials: Ninety-nine LR occurred in a patient cohort of 1,481 tumors treated with BCT. These patients were randomly matched, each with two controls. Matching was performed for age group (less than or equal to 50 and > 50 years), pN stage, and follow-up time. Histology slides were reviewed. Immunohistochemical staining was performed for the following proteins: bcl-2, CD31, cyclin D1, E-cadherin, EGF receptor, ER, PR, Ki-67, c-erbB2/neu, and p53. Statistical analyses were performed using conditional logistic regression, Results: Sixty-six cases and 139 controls with invasive carcinoma remained for analysis. The following variables were significant risk factors for LR: young age (p = 0.006), high nuclear grade (p = 0.04), high mitotic count (p 0.03), extensive DCIS around the tumor (p = 0.02) but not within the tumor, poorly differentiated type of DCIS (p = 0.03), > 20% ki-67 positive cells (p = 0.006), and PR negativity (p = 0.03), When the analysis was performed for patients I and > 50 years, these risk factors were found in the older patients, but not in the younger patients. Conclusion: High mitotic count and Ki-67 positivity are risk factors for LR, EDCIS surrounding the invasive tumor is a risk factor for LR, especially when of poorly differentiated type, Age is an important risk factor for LR independent of other risk factors, including alterations in oncogene expression. (C) 1999 Elsevier Science Inc.