Overall survival best for invasive lobular breast carcinoma patients

MedWire News: Overall survival (OS) is significantly better in patients with invasive lobular breast cancer (ILC) than in those with invasive ductal breast cancer (IDC), study findings suggest.

There have been conflicting reports on whether the different histology of IDC and ILC affects patient outcome in terms of OS and disease-free survival (DFS).

To investigate, Darius Dian (University Hospital Munich, Germany) and colleagues analyzed data from a large German population of breast cancer patients. Their results are published in the journal Archives of Gynecology and Obstetrics.

Breast cancer is histologically heterogeneous, with IDC accounting for the majority of invasive breast cancers (75–80%).

The study population included 2058 women with invasive breast cancer. Patients with metastatic disease and those who received adjuvant hormone or chemotherapy were excluded from the study.

The median duration of follow-up was 57 months (maximum 583 months). A slightly higher proportion (80%) of patients in the study had IDC, when compared with the general population, and the remaining patients had ILC.

Using multivariate analysis, tumor histology was found to be a significant prognostic indicator for OS. Kaplan–Meier survival analysis showed that IDC patients were 27% less likely to survive, compared with those with ILC (hazard ratio 0.73). There was no statistical difference in DFS between the two histologic subtypes.

The researchers suggest their results, which contradict earlier findings, may be explained by the more favourable tumor biology of ILC.

“ The fact that differences in DFS are not statistically significant could be attributable to the fact that ILC initially presents in a more diffuse pattern leading to increased rates of positive margins after breast conserving therapy,” they write.

“This phenomenon, in turn, could lead to more frequent local recurrences, which have a negative impact on DFS. Since the local disease in invasive breast cancer is secondary concerning OS, the more favorable tumour biology of ILC could still ultimately lead to better OS.”

The team concludes: “Considering the increasing numbers of patients with ILC both in Europe and in the USA it will be interesting to follow these patients in the future with regard to DFS and OS. “