Clinical Usefulness of a Multigene Testing in Patients with Special Histologic Type Breast Cancer

Area of Science:

• Oncology
• Pathology
• Genomics

Background:

• Special histologic types of breast cancer often present with atypical features, complicating prognostic assessment.
• Multigene tests (MGTs) have not been extensively studied in these rare breast cancer subtypes.

Purpose of the Study:

• To investigate the association between MGT results and histopathology in special breast cancer types.
• To evaluate the prognostic value of MGTs in patients diagnosed with special breast cancer subtypes.

Main Methods:

• Analysis of 133 patients with special histologic types of breast cancer who underwent MGTs between 2013 and 2022.
• Categorization of special types into favorable and unfavorable groups for comparative analysis.
• Evaluation of clinicopathological characteristics, MGT results, and disease-free survival (DFS).

Main Results:

• The unfavorable group (57.1%) showed higher rates of older patients, multiple tumors, grade II/III tumors, high-risk MGTs, and chemotherapy use.
• High-risk MGTs were identified in 16.5% of the cohort.
• Multivariate analysis linked grade II/III tumors, low progesterone receptor, and high Ki-67 to high-risk MGTs. MGTs significantly correlated with DFS, with no recurrences in unfavorable subtypes with low-risk MGTs.

Conclusions:

• Unfavorable special breast cancer types are more frequently associated with high-risk MGT results.
• MGT results serve as a significant prognostic factor, aiding in adjuvant therapy decisions for patients with special histologic types of breast cancer.