How Circulating Tumor Cell Count Can Inform Prostate Cancer Treatment

Circulating tumor cell (CTC) count can help inform treatment decisions for patients with cancer, including which patients are the most appropriate potential clinical trial participants, as an expert explained in an interview with CURE®.

Circulating tumor cells are material shed from tumors into the bloodstream, and they can be measured with a blood draw known as a liquid biopsy.

Researchers, who published their findings in JAMA Network Open, have found that elevated CTC count at baseline is associated with statistically significantly worse overall survival (OS), progression-free survival (PFS) and treatment response.

Study co-author Dr. Amir Goldkorn of the Division of Medical Oncology, Department of Medicine, Keck School of Medicine of USC, Los Angeles, spoke with CURE® about the findings and how they could inform patient treatment decisions.

Transcript:

What we found was that one baseline test, right at the start of when they began hormonal therapies and everything else, was able to predict how well patients were going to respond to the treatment, how long they would be responding to the treatment and how long overall they would be living with immediate overall survival with various treatments for prostate cancer. So for example, and sort of the big take-home for overall survival, was that men who had five or more CTCs in their blood at the start of treatment only lived, on average, about two and a half years, like 29 months, whereas men who had no detectable CTCs in their blood at the start of treatment, their median survival hadn't even been reached out to like 78 months, like six and a half years. We're still waiting for their average survival to hit. So they were living much, much longer.

And this is despite the fact that all these men went on to have hormonal therapies, and then they maybe progressed and went on to other treatments and chemo and this and that, you go on multiple lines of therapy for years, and yet, regardless of all that downstream stuff, that first baseline test was able to tell us, ultimately, who was going to have a shorter expected life with their cancer and who was going to survive much longer.

And the impact of that is that as we constantly strive to develop newer treatments and new combinations that may be more toxic but also more aggressive and maybe help control the cancer, we test those in clinical trials, we want to know who should be put on those trials, right? I mean, we want to ideally offer those trials to men who have very aggressive disease or are not expected to live very long with the treatments we now have. So this could be used as a test where men come in through the door, they have their CTC counts tested and say they have zero CTCs, maybe they get sort of the usual kind of standard therapies, they're going to be doing quite well with them for a long time. But if they have, say, five or 10 or 15 CTCs in the blood, we say, 'Well, OK, you're not expected to live, unfortunately, very long. This is an aggressive disease. It's going to progress quickly. You're going to not have as long a lifespan,' maybe we offer that kind of patient the newer trials with more intensified therapies or novel combinations, things like that.

Transcript has been edited for clarity and conciseness.

Reference:

“Circulating Tumor Cell Count and Overall Survival in Patients With Metastatic Hormone-Sensitive Prostate Cancer” by Dr. Amir Goldkorn et al., JAMA Network Open.

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