Ipsilateral Multifocal Primary Breast Cancer: Pathologic Assessment Using IHC

By: Jenna Carter, PhD
Posted: Tuesday, June 13, 2023

Typically, the standard of care for patients with ipsilateral multifocal primary breast cancer involves immunohistochemical (IHC) analysis of only the largest tumor; however, this practice may lead to patients not receiving optimal adjuvant treatments. In an article published in Breast Cancer Research, Slavica Janeva, MD, of the University of Gothenburg, Sweden, and colleagues highlighted the clinical significance of examining at least two tumor foci. When two or more invasive foci were assessed, the investigators found discordance of histologic type, tumor grade, and a number of biologic markers.  

“Multifocal breast cancer...occurs when two or more synchronous ipsilateral tumors affect the mammary gland. Studies show the lack of consistency regarding not only the incidence rates, but also the definition, survival, and prognosis, surgical strategy, assessment of the different foci, classification of the size(s), and the origin of the multiple tumors found,” stated Dr. Janeva and colleagues.

A total of 183 breast specimens with two or more foci were obtained from Sahlgrenska University Hospital and included in this retrospective study. IHC analyses were used to determine the expression of estrogen and progesterone receptors Ki67 and HER2. The receptor-based molecular surrogate subtypes were then determined for each focus, and data on comorbidities and postoperative adjuvant treatment were collected from patient medical records.

Findings revealed discordance in estrogen receptor, progesterone receptor, HER2, and Ki67 expression in 2.7%, 19.1%, 7.7%, and 16.9% of invasive foci, respectively. Additionally, discordance in the molecular surrogate subtypes was found in 48 of 180 patients (26.7%), which resulted in therapy changes for 11 patients (6.1%). Although these results suggest that subtype mismatches do not always lead to adjusted treatments, the study authors concluded that examining all tumor foci is recommended to assist in individualized treatment and decision-making.

Disclosure: For full disclosures of the study authors, visit biomedcentral.com.

Breast Cancer Research

---