A Comparison of the Clinicopathological Features, Metastasis Sites and Survival Outcomes of Invasive Lobular, Invasive Ductal and Mixed Invasive Ductal and Lobular Breast Carcinoma.

Objective: We compared the breast cancer patients with invasive lobular carcinoma (ILC), invasive ductal carcinoma (IDC) and mixed invasive ductal and lobular carcinoma (IDLC) in terms of clinicopathological and treatment features, metastatic patterns and long-term survival.

Materials And Methods: In a 10 years patient cohort, 3412 patients with unilateral breast carcinoma were enrolled in the study. Tumors were classified histologically according to criteria described by World Health Organization classification.

Results: The highest rate of T3 tumors were found in IDLC patients, the lowest in IDC patients, and the difference between groups was significant only in comparison of IDC vs IDLC. Axillary positivity rate was highest in IDLC, lowest in ILC; differences were significant in comparisons of IDLC vs ILC and IDLC vs IDC. There was no significant difference between the patient groups in terms of surgical treatment, mastectomy and breast conserving surgery. Rate of bone metastasis was highest in IDLC, lowest in IDC, with significant difference between IDLC and IDC. Locoregional recurrence-free survival (LRFS) rate was 90.9% in ILC patients, 92.5% in IDC patients, 92.9% in IDLC patients, with no significant difference between the groups; in multivariate Cox analysis, histological type had no prognostic significance (p=0.599). Distant metastasis-free survival (DMFS) rate was 66.2% in ILC patients, 66.7% in IDC patients, 57.1% in IDLC patients; in multivariate Cox analysis, histological type had no prognostic significance (p=0.392).

Conclusion: Although these results suggest that IDLC may have a worse prognosis than IDC and ILC, in multivariate analysis LRFS and DMFS were not significantly different among the histological type groups.