The Yale University experience of early-stage invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) treated with breast conservation treatment (BCT): analysis of clinical-pathologic features, long-term outcomes, and molecular expression of COX-2, Bcl-2, and p53 as a function of histology.

To evaluate our experience of the clinical-pathologic features and outcomes of early-stage Invasive Lobular (ILC) versus Invasive Ductal (IDC) carcinoma treated with breast conservation treatment (BCT). 142 ILC and 1,760 IDC patients were treated with BCT at our institution. All patients underwent breast conserving surgery and radiation therapy (median total dose: 64 Gy). Clinical-pathologic and outcome parameters were analyzed to detect differences between the two cohorts. In addition, COX-2, Bcl-2, and p-53 expression was analyzed from our existing tissue micro-array database. Median follow-up was 6.8 years. A higher percentage of ILC patients presented at >40 years of age (94% ILC versus 89% IDC, p = 0.0353) and had more mammographically occult tumors (p < 0.002). There were no significant differences in T stage, nodal status, family history, final margin, ER/PR/HER-2 status or triple negative tumors (all p-values >0.05). From the immuno-histochemical analysis, expression of p53, COX-2, and Bcl-2 did not differ significantly (all p-values >0.05) between the two cohorts. At 10 years, there was no difference in breast relapse (20% versus 13%, p = 0.25), distant relapse (26% versus 20%, p = 0.28), cause-specific survival (72% versus 84%, p = 0.09) and OS (68% versus 78%, p = 0.08). Patients with ILC had higher contralateral breast relapses (26% versus 12%, p = 0.0006). Patients with early-stage ILC have comparable outcomes to IDC when treated with BCT. Because of the higher risk of contralateral breast cancers for ILC patients, careful evaluation of the contralateral breast will be important in the follow-up of these patients. Future investigations of chemo-preventive strategies to decrease contralateral breast cancers are warranted.