Circulating tumor cell count could help choose treatment for metastatic breast cancer patients

December 6, 2018, American Association for Cancer Research
Credit: CC0 Public Domain

Circulating tumor-cell (CTC) count could be used to choose hormone therapy or chemotherapy as frontline treatment for patients with estrogen receptor-positive (ER+), HER2-negative (HER2-) metastatic breast cancer, according to data from the phase III STIC CTC clinical trial presented at the 2018 San Antonio Breast Cancer Symposium, held Dec. 4–8. In the case of discrepancy between CTC count-based treatment choice and physician's choice of treatment, frontline chemotherapy was associated with a significant gain in overall survival.

"Two main treatment options exist for patients newly diagnosed with metastatic, ER+, HER2- breast cancer: or (eventually followed by maintenance hormone therapy). There is unfortunately no validated predictive biomarker to guide that choice," said Francois-Clement Bidard, MD, Ph.D., Professor of Medical Oncology at Institut Curie (Saint Cloud, France) and University of Versailles.

While frontline hormone therapy is the preferred treatment option because of limited side effects, chemotherapy is proposed in patients presenting with adverse prognostic factors, Bidard explained. These factors are, however, not well defined in the current literature and, as the choice between hormone therapy and chemotherapy relies on the doctor's estimate of the patient prognosis, different doctors may, in turn, propose different treatments to the same patient, he noted.

"CTC count has been investigated in thousands of worldwide over the past decade, and numerous analyses have established that, beyond performance status, CTC count is the strongest prognostic marker in ER+, HER2- stage 4 breast cancer patients," Bidard said. His team studied whether CTC count can be used to assess a patient's prognosis and personalize the choice between hormone therapy and chemotherapy.

"In our study, not only have we demonstrated that basing the decision on CTC count alone does not harm patients in the overall study population (primary objective), but subgroup analyses show that, in the 292 patients with discordant treatment recommendations (between the clinician estimate and the CTC count), frontline chemotherapy was associated with a significant 35 percent decrease in the risk of death," Bidard said.

In this trial, 778 patients were randomly assigned 1:1 to a clinically driven treatment arm (hormone therapy or chemotherapy was administered as decided by a physician based on clinical factors) or a CTC-driven treatment arm (hormone therapy was administered if 7.5 ml blood had less than 5 CTC and chemotherapy was administered if 7.5 ml blood had 5 or more CTC).

After randomization, in the clinically driven arm, 72.6 percent of the patients received hormone therapy and 27.4 percent received chemotherapy. In the CTC-driven arm:

  • Among those likely to receive hormone therapy by clinically driven choice, this treatment option was confirmed by a low CTC count in 66.7 percent of the patients; the remaining 33.3 percent were switched to chemotherapy based on a high CTC count;
  • Among those likely to receive chemotherapy by clinically driven choice, this treatment option was confirmed by high CTC count in 48.1 percent of the patients; the remaining 52.9 percent were switched to hormone therapy based on low CTC count.

The study met its primary endpoint (assessed in the 778 patients), with progression-free survival (PFS) not being inferior in the CTC-driven arm, compared with the clinically driven arm.

Patients whose treatment was escalated to chemotherapy based on CTC count had a significantly longer PFS (median PFS was 10.5 months with hormone therapy in the clinically driven arm who had high CTC count, versus 15.5 months with chemotherapy in the CTC arm) and showed a trend toward longer overall survival (OS, 37.1 vs. 42.0 months). In contrast, patients whose treatment was de-escalated to hormone therapy based on CTC count had non-significantly shorter PFS and OS compared with those who received chemotherapy in the clinically driven arm who had low CTC count.

In an exploratory analysis, pooling the two subgroups of patients (292) with discordant treatment recommendations showed that patients treated with frontline chemotherapy had significantly longer PFS (34 percent less likely to have their disease progress) and OS (35 percent lower risk of death). Overall survival rates at 24 months were 82.9 percent in patients treated with chemotherapy (eventually followed by maintenance hormone therapy) vs. 74.7 percent in treated with frontline hormone therapy.

"Since the 1990s, no trial has assessed the question of front-line therapy, and our results suggest that modern prognostic biomarkers, such as the CTC , may lead to better patient survival," Bidard added.

Bidard noted that a main limitation of the study is that during the STIC CTC study follow-up, CDK4/6 inhibitors (palbociclib, ribociclib, and abemaciclib) became largely used as first-line , therefore, doctors are more likely to recommend front-line therapy combined with CDK4/6 inhibitors rather than chemotherapy.

Explore further: Some patients with metastatic triple negative breast cancer live longer with immunotherapy

Related Stories

Some patients with metastatic triple negative breast cancer live longer with immunotherapy

October 22, 2018
Immunotherapy improves survival in some patients with metastatic triple negative breast cancer, according to late-breaking results from the IMpassion130 trial reported at the ESMO 2018 Congress in Munich.

Phase III KATHERINE trial crossed early reporting boundary and met its primary endpoint

December 5, 2018
Substituting trastuzumab emtansine (T-DM1, Kadcyla) for adjuvant trastuzumab (Herceptin) in patients who had residual disease after receiving neoadjuvant chemotherapy and trastuzumab reduced the risk of developing an invasive ...

Delaying adjuvant chemo associated with worse outcomes for patients with triple-negative breast cancer

December 5, 2018
Patients with triple-negative breast cancer who delayed starting adjuvant chemotherapy for more than 30 days after surgery were at significantly higher risk for disease recurrence and death compared with those who started ...

Major trial shows targeted drug extends breast cancer survival

October 22, 2018
Combining a targeted drug with hormone therapy substantially extends survival for women with advanced breast cancer, a major clinical trial has found.

Combo treatment may boost survival with advanced prostate cancer

August 6, 2015
(HealthDay)—Chemotherapy at the start of hormone therapy can extend the lives of men with prostate cancer that has spread beyond the gland, a new study finds.

TAILORx trial finds most women with early breast cancer do not benefit from chemotherapy

June 4, 2018
New findings from the groundbreaking Trial Assigning Individualized Options for Treatment (Rx), or TAILORx trial, show no benefit from chemotherapy for 70 percent of women with the most common type of breast cancer. The study ...

Recommended for you

Immunotherapy combo not approved for advanced kidney cancer patients on the NHS

December 14, 2018
People with a certain type of advanced kidney cancer will not be able to have a combination of two immunotherapy drugs on the NHS in England.

New drug seeks receptors in sarcoma cells, attacks tumors in animal trials

December 13, 2018
A new compound that targets a receptor within sarcoma cancer cells shrank tumors and hampered their ability to spread in mice and pigs, a study from researchers at the University of Illinois reports.

Surgery unnecessary for many prostate cancer patients

December 13, 2018
Otherwise healthy men with advanced prostate cancer may benefit greatly from surgery, but many with this diagnosis have no need for it. These conclusions were reached by researchers after following a large group of Scandinavian ...

Combining three treatment strategies may significantly improve melanoma treatment

December 12, 2018
A study by a team led by a Massachusetts General Hospital (MGH) investigator finds evidence that combining three advanced treatment strategies for malignant melanoma—molecular targeted therapy, immune checkpoint blockade ...

Researchers use computer model to predict prostate cancer progression

December 12, 2018
An international team of cancer researchers from Denmark and Germany have used cancer patient data to develop a computer model that can predict the progression of prostate cancer. The model is currently being implemented ...

New insight into stem cell behaviour highlights therapeutic target for cancer treatment

December 12, 2018
Research led by the University of Plymouth and Technische Universität Dresden has identified a new therapeutic target for cancer treatment and tissue regeneration – a protein called Prominin-1.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.