Findings have already changed practice
Senior author, Mark Levine, MD, MSc, also with McMaster, said in an interview that the results of this study have already changed practice in Canada, and he expects the United States to follow suit.
Dr. Levine said the study is important “in terms of helping plan therapy and being very open and honest with patients as to their prognosis.”
The findings constitute level 1 evidence in favor of PET-CT. Already, in Canada, “because of the results of the study, people with stage III breast cancer can get a PET scan,” he said.
Dr. Levine said he expects this evidence also to clarify “wishy-washy” National Comprehensive Cancer Network guidelines on using PET scans for LABC in the United States when the guidelines are next updated.
“That will make it easier for payers in the United States,” he added.
Cost effectiveness, Dr. Levine said, is complicated, because on one hand PET scans are quite costly. But its use would lead to more women getting less aggressive and expensive therapy and surgery.
Dr. Levine noted that his team will be analyzing cost-effectiveness over the next year.
New questions with more in stage IV
In an editorial, Lajos Pusztai, MD, DPhil, scientific codirector of the breast center at Yale University in New Haven, Conn., noted that, “all good studies raise new questions” and this one is no exception.
He pointed out that the number of women with stage IV metastatic breast cancer (MBC) has been increasing over the past 2 decades because of more sensitive staging methods. At the same time the number of women with recurrent metastatic disease is decreasing, because adjuvant therapies have improved.
Findings highlight need for stage IV treatment studies
Dr. Pusztai noted that the patients who have de novo oligometastatic stage IV disease “are a unique subset among patients with MBC,” and the best treatment [for them] has not been established in randomized, controlled trials.
“Almost all randomized trials that targeted oligometastatic patients accrued mostly recurrent metastatic cancers; many included various cancer types, and none have tested the value of systemic multidrug regimens administered with curative intent,” he wrote.
If the health care systems adopt PET-CT for routine staging of locally advanced breast cancer, that will increase the diagnosis of de novo oligometastatic stage IV breast cancer, Dr. Pusztai said. That “underlines the importance of conducting studies for this unique subset of patients to establish level 1 evidence-based treatment strategies.”
Dr. Dayes has received honoraria from Verity Pharmaceuticals. One coauthor is employed by Point Biopharma. Other coauthors reported ties with AbbVie, Agendia, Genomic Health, InMode and Lutronic. Dr. Pusztai’s institution has received research funding from Merck, Genentech, Seagen, AstraZeneca, Bristol Myers Squibb, and Pfizer. He has received honoraria and travel expenses and has served in a consulting role for several pharmaceutical companies. Full disclosures are available on Open Payments.