Clinical Risk Score in HR+/ERBB2- Breast Cancer an Indicator for Routine Genetic Testing

Low clinical risk score (CRS) and low composite risk score of distant recurrence (Regan Risk score [RRS]) in patients with early stage hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (ERBB2−) breast cancer did not correlate with high genomic risk score (GRS), suggesting that genomic testing may be safely omitted, regardless of tumor size, in these patients. These findings were published in Clinical Breast Cancer.

Read more: Genetic Testing in Breast Cancer

The genomic assay Oncotype DX (Exact Sciences; Madison, Wisconsin) is used to quantify the risk of early stage HR+/ERBB2− breast cancer recurrence and guide treatment decisions for this patient population.

In this study, researchers sought to assess the clinical utility of genomic recurrence risk stratification compared with clinical risk stratification in HR+/ERBB2− breast cancer.

A retrospective chart review of adult patients with early stage HR+/ERBB2− breast cancer identified 517 patients, with clinical data available for 501 of them. Clinical risk of recurrence was assessed using a CRS based on tumor size and histologic grade and a composite risk score of distant recurrence (RRS). Genomic risk score was assessed with Oncotype DX, a 21-gene expression assay.

CRS was defined as low if tumor size was ≤3 cm in diameter with grade 1 histology, tumor size ≤2 cm with grade 2 histology, or tumor size ≤1 cm with grade 3 histology; CRS was defined as high if the low-risk criteria were not met. Information to compute CRS was available for all 501 patients.

RRS is a composite of age, Ki-67 expression levels, estrogen receptor and progesterone receptor expression levels, number of positive lymph nodes, tumor size, and tumor grade. Low risk was defined as RRS ≤1.41 (3rd quartile). The molecular data required to compute RRS was available for only 374 patients.

Among patients with low CRS, 9.17% had a high GRS (32/349 patients); among patients with a low RRS, 8.93% of patients had a high GRS (25/280 patients).

Of the patients with grade 1 histology, 3.85% had a high GRS (5/130 patients). Among these patients, 68.46% had a tumor >1 cm (89/130 patients) and only 4.49% of them (4/89 patients) had a high GRS. One patient with a tumor size ≤1 cm had a high GRS (1/41 patients), and tumor size >1 cm did not associate with high GRS.

These findings show that less than 10% of patients with low clinical risk and less than 5% of patients with grade 1 tumors had a high GRS.

“Given current NCCN recommendation for testing, our findings raise the question of whether genomic testing for patients with grade 1 tumors can be safely omitted, irrespective of size, and call for a better understanding of the need for routine genomic testing in patients with low grade/low clinical risk of recurrence following adjuvant endocrine therapy,” the researchers wrote in conclusion. “Further studies are warranted to identify the most cost-effective testing strategies.”

Reference

Choucair K, Page SJ, Mattar BI, et al. Clinical utility of genomic recurrence risk stratification in early, hormone-receptor-positive, human epidermal growth factor receptor 2-negative breast cancer: real-world experience. Clin Breast Cancer. 2023;23(2):155-161. doi:10.1016/j.clbc.2022.11.005