Analysis of Oncotype DX recurrence score and its clinical implications in invasive lobular carcinomas of the breast

Background

The Oncotype DX breast cancer assay is increasingly being used to guide treatment decisions for patients with early stage, hormone-positive, Her-2 negative breast cancer, regardless of the histologic subtype. The utility of the Oncotype DX in decision making for treatment of invasive lobular carcinoma (ILC) has not been investigated.

Methods

We performed a retrospective analysis of early stage breast cancer patients treated at Penn State Cancer Institute from 2001 to 2011 and identified 102 patients with ILC. We evaluated the clinicopathological features and compared the Recurrence Score (RS) distribution in this population to that reported by Genomic Heath for the ductal histology (Kruskal-Wallis test). Median follow-up was 4.5 years

Results

We found that the RS distribution for ILC differed significantly from that reported by Genomic Health (P 

Conclusions

The Oncotype DX RS distribution in invasive lobular carcinoma is unique, differing significantly from that in invasive ductal carcinoma. Majority of patients (97.8%) have low/intermediate RS and 93.3% have RS ≤ 25 and would not be candidates for adjuvant chemotherapy. The clinical usefulness and cost-effectiveness of the Oncotype DX in guiding treatment for ILC should be further investigated.

Clinical trial identification

Legal entity responsible for the study

Jesse Felts Cristina Truica

Funding

Pink Zone and Lady Lion Basketball Breast Cancer Research Endowment and the Federal US Work Study program

Disclosure

All authors have declared no conflicts of interest.