C. Kent Osborne, MD, FASCO

Lisa Carey, MD

C. Kent Osborne, MD, FASCO, Director of the Dan L. Duncan Comprehensive Cancer Center at Baylor College of Medicine, Houston, who moderated a press briefing where the results were presented, called the findings “intriguing” but too premature for the clinic.

“We don’t know what to do with the data yet—similar to the use of circulating tumor cells in metastatic breast cancer. We know there was a worse-prognosis category depending on how many circulating tumor cells a patient had, but this didn’t help us change therapy,” he said. “The question that needs to be answered before taking this into the clinic is, for circulating tumor cell–positive patients, ‘Treat me now? Or wait until I recur, and then treat me?’” he asked.

“We have to be able to show that treating patients who test positive [for circulating tumor cells] provides a benefit. Until then, why get the test? Furthermore, not everyone who is positive recurs within that 2-year period [the time of follow-up],” he pointed out.

“We might be able to intervene effectively, but it may just take time to show it,” Dr. Osborne continued. “If we found recurrences at a microscopic stage and implemented treatment when we first see circulating tumor cells, maybe we could catch the disease early and possibly cure it.”

Words of Caution

ERIC P. WINER, MD, FASCO, Director of the Breast Oncology Center at -Dana-Farber Cancer Institute, Boston, emphasized that late recurrences are a “major unmet challenge” in hormone receptor–positive breast cancer, but at this point, there is no good way to identify which patients are most at risk. “At this time, I don’t think clinicans should order circulating tumor cell assays or any of the available genomic indices to try to predict who is at greatest risk. That said, a variety of clinical parameters are predictive of late recurrence. In general, in patients with hormone receptor–positive disease, the factors that predict for early recurrence also predict for late recurrence,” he said.

Lisa Carey, MD, the Richardson and Marilyn Jacobs Preyer Distinguished Professor in Breast Cancer Research at the University of North Carolina Lineberger Comprehensive Cancer Center, also urged caution. “Personally, I think the circulating tumor cell story is not that different from using scans for surveillance. Until you can show that you can improve outcomes, we can predict relapse with things we have in our hands now.” ■

DISCLOSURE: Drs Osborne, Winer, and Carey reported no conflicts of interest.