The Importance of the Pathological Perspective in the Management of the Invasive Lobular Carcinoma.

Background: Invasive lobular carcinomas (ILC) account for 10-15% of all breast cancers and are the second most common histological form of breast cancer. They usually show a discohesive pattern of single cell infiltration, tend to be multifocal, and the tumor may not be accompanied by a stromal reaction. Because of these histological features, which are not common in other breast tumors, radiological detection of the tumor may be difficult, and its pathological evaluation in terms of size and spread is often problematic. The SSO-ASTRO guideline defines the negative surgical margin in breast-conserving surgeries as the absence of tumor detection on the ink. However, surgical margin assessment in invasive lobular carcinomas has not been much discussed from the pathological perspective.

Methods: The study included 79 cases diagnosed with invasive lobular carcinoma by a Tru-cut biopsy where operated in our center between 2014 and 2021. Clinicopathological characteristics of the cases, results of an intraoperative frozen evaluation in cases that underwent conservative surgery, the necessity of re-excision and complementary mastectomy, and consistency in radiological and pathological response evaluation in cases receiving neoadjuvant treatment were questioned.

Results: The tumor was multifocal in 37 (46.8%) cases and single tumor focus in 42 (53.2%) cases. When the entire patient population was evaluated, regardless of focality, mastectomy was performed in 27 patients (34.2%) and breast-conserving surgery (BCS) was performed in 52 patients (65.8%). Of the 52 patients who underwent BCS, 26 (50%) required an additional surgical procedure (cavity revision or completion mastectomy). There is a statistical relationship between tumor size and additional surgical intervention ( < 0.05). BCS was performed in 7 of 12 patients who were operated on after neoadjuvant treatment, but all of them were reoperated with the same or a second session and turned to mastectomy. Neoadjuvant treatment and the need for reoperation were statistically significant ( < 0.05). Additional surgical procedures were performed in 20 (44.4%) of 45 patients in BCS cases who did not receive neoadjuvant therapy.

Conclusions: Diagnostic difficulties in the intraoperative frozen evaluation of invasive lobular carcinoma are due to the different histopathological patterns of the ILC. In our study, it was determined that large tumor size and neoadjuvant therapy increased the need for additional surgical procedures. It is thought that the pathological perspective is the determining factor in order to minimize the negative effects such as unsuccessful cosmesis, an additional surgical burden on the patient, and cost increase that may occur with additional surgical procedures; for this reason, new approaches should be discussed in the treatment planning of invasive lobular carcinoma cases.