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Nearly a quarter of women with small breast cancers at risk for distant metastases
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MADRID — Nearly one-quarter of women with small breast cancers are at risk for distant metastases and may derive benefit from adjuvant chemotherapy, according to a substudy of the MINDACT trial presented at the European Society for Medical Oncology Congress.
Those with T1a or T1b node-negative tumors who are deemed at low clinical risk but high genomic risk achieved better distant metastases-free survival, DFS and OS with adjuvant chemotherapy administration.
These results suggest clinicians should not automatically consider all small tumors as less serious and forego adjuvant chemotherapy, Konstantinos Tryfonidis, MD, medical oncologist and researcher at the European Organization for Research and Treatment of Cancer in Brussels, said during his presentation.
“Decision-making in patients with [T1a or T1b] node-negative tumors must take into account the biology of the disease, as well as other factors such as performance status, comorbidity, age and patient preferences,” Tryfonidis said.
The MINDACT study included 6,693 women with early-stage breast cancer, defined as lymph node negative or one to three positive nodes.
Previously reported results showed nearly half (46%) of women who were at high clinical risk for recurrence — as determined by the Adjuvant! Online tool, which relies on common clinical and biologic criteria — may not require chemotherapy. That’s because they demonstrated a low genomic risk for recurrence as determined by MammaPrint (Agendia), a 70-gene signature that helps predict outcomes for women with early-stage disease.
The subanalysis from MINDACT presented at ESMO began with 826 women whose primary tumors measured less than 1 cm.
More than one-third (37.5%) of women were aged 60 years or older, and 63.6% were postmenopausal. The majority had invasive ductal tumors (80.5%) and ER-positive disease (91.1%); 6.3% had HER-2-positive disease; 5.1% had triple-negative disease; and 11.1% had grade 3 tumors.
From this group, Tryfonidis and colleagues identified 196 women (23.7%) who had low clinical risk as determined by Adjuvant! Online but high genomic risk as determined by MammaPrint. Researchers randomly assigned these women to adjuvant chemotherapy or no chemotherapy.
At 5 years, few patients who received chemotherapy experienced relapse. At that time point, a higher percentage of women assigned chemotherapy achieved distant metastases-free survival (97.3% vs. 91.4%) and distant metastases-free interval (98.8% vs. 91.4%). Also, a higher percentage of women who received chemotherapy remained alive at 5 years (98.5% vs. 95.8%).
The determination that nearly one in four women with small tumors were at risk for distant metastases was “striking,” according to Fatima Cardoso, MD, co-principal investigator of MINDACT and director of the breast unit at Champalimaud Clinical Centre in Lisbon, Portugal, said in a press release.
“Based on clinical criteria alone, you would say that these tumors are not aggressive and, therefore, patients do not need chemotherapy,” Cardoso said. “But 24% of small tumors had an aggressive biology, which shows that not all tumors are the same.” – by Chuck Gormley
Reference:
Tryfonidis K, et al. Abstract 150O_PR. Presented at: European Society for Medical Oncology Congress; Sept. 8-12, 2017; Madrid.
Disclosures: Cardoso reports consultant roles with Astellas/Medivation, AstraZeneca, Celgene, Daiichi-Sankyo, Eisai, GE Oncology, Genentech, GlaxoSmithKline, Macrogenics, Merck Sharp & Dohme, Merus BV, Novartis, Pfizer, Pierre-Fabre, Roche, Sanofi and Teva. Please see the abstract for a list of all other researchers’ relevant financial disclosures.
Perspective
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Hope S. Rugo, MD
These are excellent data on the natural history of mostly hormone receptor-positive, T1b breast cancers. MINDACT will continue to provide us with a lot of great information. Most of the cancers in this study were both clinically and genomically low risk based on MINDACT classifications. The majority of discordant cases were luminal B, HER-2 positive or basal breast cancers. The benefit from chemotherapy is impossible to assess given the low numbers of patients and very few events; indeed, it was a very small benefit in the HER-2-negative population. Biology is critical to treatment decisions for early-stage breast cancer, but treatment decisions have to take into account risk vs. benefit given the excellent overall outcomes in this group of patients with very small tumors. Really, in the end, it’s not clear how much genomic analysis in these very small tumors — particularly those that are ER-positive — helps us with decision-making given the heterogeneous clinical features in this database.
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