Purpose: The purpose of this study was to determine the prognostic significance of cyclin D1 (cycD1) levels in ipsilateral breast tumor recurrence (IBTR) following lumpectomy and radiation therapy.
Methods and materials: A total of 98 patients (49 patients with IBTR and 49 matched cases without IBTR) selected from our conservatively treated breast cancer population served as the patient population for the current study. All patients were treated with lumpectomy followed by radiation therapy to the intact breast to a total median dose of 64 Gy. The patients were followed in our clinic with a median follow-up of 13 years. Immunohistochemical analysis of cycD1 in these 98 early-stage breast cancer patients was performed using a polyclonal antibody generated against the human cycD1 protein. All clinical, pathologic, and molecular variables were entered into a computerized data base for statistical analysis.
Results: Low levels of immunohistochemically detected cycD1 protein correlated with IBTR (p = 0.001), but there was no association between cycD1 protein levels and metastatic disease, axillary lymph node involvement, distant disease-free survival (DDFS), and overall survival (OS). Subgroup analysis revealed that for early breast tumor relapses (within 4 years of initial breast tumor diagnosis), low levels of cycD1 were associated with IBTR (p = 0.004), but cycD1 expression was not prognostic for IBTR from breast cancer patients with late relapses (p = NS).
Conclusion: These studies provide in vivo evidence for the prognostic and biologic significance of cycD1 expression in determining response to radiation therapy in breast cancer patients.