INFILTRATING LOBULAR CARCINOMA - IS IT DIFFERENT FROM INFILTRATING DUCT CARCINOMA

Background. Infiltrating lobular carcinomas (ILC) represent approximat ely 10% of all breast cancers. The literature is mixed regarding their prognosis when compared with infiltrating duct carcinomas (IDC). Ther e are few data regarding the treatment of ILC with radiation therapy. Methods. The clinical, pathologic, laboratory, and survival data of 16 1 patients with ILC were compared with the data of 1138 patients with IDC. Results. ILCs were larger, more difficult to excise completely, a nd more difficult to diagnose clinically. All prognostic factors measu red were more favorable for ILC. Nodal positivity for ILC was 32%, com pared with 31% for IDC (P = 0.221. The 7-year disease-free Kaplan-Meie r survival (DFS) was 74% for patients with ILC and 63% for patients wi th IDC (P < 0.03). The 7-year breast cancer specific survival (BCSS) w as 83% for patients with ILC and 77% for patients with IDC (P < 0.04). Selected patients with smaller lesions were treated with excision and radiation therapy. Patients with ILC treated with radiation therapy h ad a better DFS and BCSS than did patients with IDC treated with radia tion therapy. Conclusions. ILCs often are homogeneous, small cell tumo rs of low nuclear grade. Their desmoplastic reaction may be absent or less marked than that of IDC, making them more difficult to palpate an d to visualize mammographically. Despite this, they can be treated suc cessfully with either mastectomy or excision and radiation therapy.