Quantitative mRNA Expression Assays and Synchronous Breast Cancers: A Case Report

Area of Science:

• Oncology
• Genomics
• Precision Medicine

Background:

• National Comprehensive Cancer Network (NCCN) guidelines recommend quantitative mRNA profiling for early-stage, hormone receptor-positive, HER2-negative breast cancers to guide adjuvant therapy decisions.
• Quantitative mRNA assays like the 21-gene RT-PCR (Oncotype Dx) predict recurrence risk and response to endocrine therapy versus chemotherapy.

Observation:

• Synchronous primary breast cancers are rare, with limited data on their combined distant recurrence risk.
• The recurrence risk from two primary breast cancers may exceed the risk from the larger single tumor.

Findings:

• This report details a case of synchronous primary breast cancers where Oncotype Dx was performed on both tumors.
• A novel calculation method was used to estimate the combined recurrence risk, treating each tumor's risk as an independent event.
• The proposed calculation method aims to provide a more accurate prediction of recurrence risk compared to using the higher of the two individual Oncotype Dx scores.

Implications:

• This approach may improve risk stratification for patients with multiple primary breast cancers.
• Accurate recurrence risk assessment is crucial for optimizing adjuvant endocrine therapy and chemotherapy decisions in precision oncology.
• Further research is needed to validate this combined risk calculation method in a larger cohort of patients with synchronous breast cancers.