For patients with grade 3 breast cancer, recurrence score testing may have significant clinical value in determining which patients are likely to benefit from chemotherapy, according to investigators who recently reported results of a large, national cohort study.
Among patients with pN0/1 grade 3 invasive breast cancers, about one-third had a low recurrence score, which was associated with no early benefit from the addition of chemotherapy, wrote senior study author Jane E. Brock, MBBS, PhD, of Harvard Medical School, Boston, and coauthors.
Incorporating recurrence score testing into clinical decision making may help “tailor treatment recommendations” for patients with grade 3 invasive breast cancers, Dr. Brock and coauthors reported in JCO Precision Oncology.
“To our knowledge, these findings represent the largest analysis to date of the potential impact of recurrence score on the outcomes and management of grade 3 tumors, and suggest that the assumption that all pT1c/2 pN0/1, [estrogen receptor–positive] histopathologic grade 3 tumors are high risk and will consequently benefit from adjuvant chemotherapy may be unmerited,” the Dr. Brock and coauthors wrote in the report.
These findings “fill a gap” as the final results of the RxPONDER trial are awaited, according to investigators. Specifically, RxPONDER is designed to evaluate the potential benefit of adjuvant chemotherapy in pN0/1 patients with intermediate range recurrence scores.
Moreover, the findings complement the reported results of the TAILORx trial, which showed that chemotherapy does not provide a benefit in most low and intermediate recurrence score tumors, which suggests some patients may safely omit chemotherapy without affecting outcomes, the investigators added.
The present analysis included a total of 30,864 grade 3 breast cancers from the National Cancer Database, which represents more than 70% of new diagnoses in the United States, according to investigators.
Testing using the 21-gene Oncotype DX Breast Recurrence Score increased over time for pN0 cancers, from 53% in 2010 to 72% in 2015, investigators found; likewise, for pN1 cancers, testing increased from 16% to 36% over that time period. They also found that, overall, 30% of pN0 and 27.1% of pN1 cancers had a low recurrence score.
Adjuvant chemotherapy was not associated with any additional benefit in patients with low recurrence scores, according to the analysis.
For patients with intermediate recurrence scores, chemotherapy was linked to improved survival in univariable analyses, but following adjustment for clinical and pathologic characteristics, intermediate scores were not predictive of a significant overall survival benefit, investigators found.
By contrast, chemotherapy was associated with additional benefit in patients with high recurrence scores in both univariable and multivariable analyses.
For patients with pN0 grade 3 disease and high recurrence score, chemotherapy was linked to significantly improved overall survival, compared with that of patients who received no chemotherapy (hazard ratio, 0.63; 95% confidence interval, 0.43-0.90; P = .01), while a similar survival benefit was reported among patients with pN1 disease and high recurrence scores (HR, 0.24; 95% CI, 0.13-0.47; P less than .001).
These results suggest that recurrence score may aid in determining the anticipated benefit of chemotherapy in this heterogeneous cohort of patients, investigators wrote.
“Furthermore, our findings show significant variability in national patterns of recurrence testing and chemotherapy use for grade 3 disease, which suggests opportunities for more comprehensive national guidelines for recurrence score testing in high-grade tumors,” they concluded.
Dr. Brock reported no potential conflicts of interest. Coauthors provided disclosures related to AstraZeneca, Blade Therapeutics, Eisai, EMD Serono, Galena Biopharma, Genentech, Genomic Health, Novartis, Novartis Institutes for BioMedical Research, Peregrine, Puma Biotechnology, resTORbio, Roche, and others.
SOURCE: Brock JE et al. JCO Precis Oncol. 2019 Aug 14. doi: 10.1200/PO.19.00029.