Researchers evaluated the clinical utility of genetic testing with MammaPrint 70-gene signature to determine how well this assay works in comparison with clinical assessment to determine the need for chemotherapy in women with breast cancer involving 0 to 3 lymph nodes. The phase 3 MINDACT findings, which included the survival outcomes of patients with an ultralow risk 70-gene signature, were presented during the 2021 American Society of Clinical Oncology Annual Meeting.

The 70-gene signature can identify patients with an ultralow risk of distant recurrence. These 1000 MINDACT patients had an excellent 8-year breast cancerspecific survival (BCSS) above 99%, regardless of clinical risk, and low rates of distant metastasis, explained Josephine Lopes Cardozo, MD, of the Netherlands Cancer Institute.

The median follow-up for disease assessment was 8.7 years. Of the 6693 patients enrolled in the study (ClinicalTrials.gov Identifier: NCT00433589), 1000 patients (15%) were identified as having an ultralow risk using 70-gene signature profiling and 67% of these patients were older than age 50. A majority of the patients were estrogen receptorpositive (99%), lymph nodenegative (80%), had grade 1 or 2 tumors (96%), and tumors below 2 cm in size (81%).

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Systemic therapy was administered in 83% of the study population; 69% of patients received endocrine therapy (ET), 14% received ET in combination with chemotherapy, and 16% did not receive adjuvant systemic therapy (AST). The trials primary endpoint was distant metastasis-free interval (DMFI).

At a median duration of 8 years, excellent DMFI and BCSS was observed in the low-risk and ultralow-risk group of patients. The 8-year DMFI for low-risk and ultralow-risk groups was 94.5% (95% CI, 93.6-95.3) and 97.0% (95% CI, 95.8-98.1), respectively. The 8-year DMFI in the ultralow-risk group who had not received AST was 97.8% (95% CI, 95.3-100). The 8-year DMFI in the ultralow-risk group who had received ET only was 97.4% (95% CI, 96.1-98.7). Based on the preliminary results after adjusting for tumor and treatment characteristics, DMFI for ultralow-risk vs low-risk groups had a hazard ratio (HR) 0.66 (95% CI, 0.46-0.95). The 8-year BCSS for genomic low-risk and ultralow-risk patients was 98.2% (95% CI, 97.7-98.7) and 99.6% (95% CI, 99.1-100), respectively.

We can confirm that the 70-gene signature can identify patients with ultralow risk of distant recurrence and these patients could be candidates for further de-escalation of treatment, further reducing overtreatment and the risk of side effects, concluded Dr Cordozo.

Disclosure: This research was supported by a grant from the EORTC Breast Group and the Netherlands Cancer Institute. Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors disclosures

Read more ofCancer Therapy Advisorscoverage of the 2021 ASCO Annual Meeting by visiting the conference page.

Reference

Cardozo JL, Drukker C, Schmidt M, et al. Outcome of patients with an ultralow risk 70-gene signature in the MINDACT trial. J Clin Oncol. 2021;39:(suppl 15; abstr 500). doi:10.1200/JCO.2021.39.15_suppl.500

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MammaPrint 70-Gene Signature Identifies Ultralow-Risk Patients With Outstanding Prognosis in Breast Cancer - Cancer Therapy Advisor

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