According to a recent study, enumeration of circulating tumor cells (CTCs) may be useful for determining long-term prognosis and guiding treatment selection in patients with metastatic castration-sensitive prostate cancer (mCSPC).1 A second study has shown similarly predictive value for CTC counts in metastatic breast cancer.2

Researchers used the CellSearch circulating tumor cell test, from Menarini Silicon Biosystems, Huntingdon Valley, Pa, to detect and count CTCs.

A Lack of Accurate Biomarkers

A current challenge in treating mCSPC is the lack of accurate biomarkers that indicate which patients will do well with particular therapies or how long patients will live. In the recent study, researchers determined that CTC counts are a noninvasive way to obtain valuable prognostic information at the start of treatment.

Fabio Piazzalunga, Menarini Silicon Biosystems.

Fabio Piazzalunga, Menarini Silicon Biosystems.

“These findings have important clinical implications, suggesting that patients with high initial CTC counts are less likely to respond and more likely to progress on hormonal therapy,” says Amir Goldkorn, MD, associate professor of medicine at the University of Southern California Keck School of Medicine and lead researcher for the study. “Though additional analysis is required, these results indicate that CTCs could become a valuable biomarker that can tell us about a patient’s long-term prognosis and help guide therapy.”

The study investigated mCSPC patients early in the disease, when participants were first being treated with hormone therapy. Researchers enumerated CTCs in 1,200 men at the start of the study, and then looked at two endpoints: the level of prostate-specific antigen (PSA) after 7 months, and progression-free survival after 2 years.

The study results showed clear prognostic value for the CTC count. The 63% of men who had no circulating tumor cells when the study began were more than six times more likely at 7 months to have PSA values below 0.2, which has been shown to be highly correlated with longer survival times than higher PSA values. The men were also 3.7 times more likely to survive, with no cancer progression, after 2 years.

CTCs and ctDNA Mutations in Metastatic Breast Cancer

The second study examined the role of CTC counts and mutations in circulating tumor DNA (ctDNA) for predicting prognosis, treatment response, and disease spread in metastatic breast cancer. Led by Massimo Cristofanilli, MD, FACP, associate director for translational research at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University, the researchers looked at 36 Stage III and 203 Stage IV breast cancer patients.

They found that CTC counts were much higher among Stage IV patients—an average of 62.2 cells per 7.5 mL of blood compared to 14.5 cells in Stage III patients—and that within each group, high CTC counts predicted worse outcomes. In addition, they discovered that mutations in one particular gene in ctDNA—known as PI3KCA—dramatically increased in Stage IV patients compared to Stage III patients and were also highly predictive of worse prognosis and treatment outcomes.

The researchers examined tumor cell candidates using the CellTracks Analyzer II system from Menarini Silicon Biosystems.

“These new studies demonstrate the important role our rare cell technologies play in advancing precision medicine research, which could one day translate to better, more personalized treatment options for patients with prostate and breast cancer,” says Fabio Piazzalunga, president and chief executive officer of Menarini Silicon Biosystems.

For more information, visit Menarini Silicon Biosystems.


1. Goldkorn A, Tangen C, Plets M, et al. Baseline circulating tumor cell (CTC) count as a prognostic marker of PSA response and progression in metastatic castrate sensitive prostate cancer (mCSPC): results from SWOG S1216, a phase III randomized trial of androgen deprivation plus orteronel (cyp17 inhibitor) or bicalutamide [abstract 5506, online]. Presentation at the virtual scientific program of the American Society of Clinical Oncology, Alexandria, Va, May 29–31, 2020. J Clin Oncol. 2020;38:(suppl):5506; doi: 10.1200/jco.2020.38.15_suppl.5506.

2. Zhang Q, Zheng C, Gerratana L, et al. Circulating tumor DNA (ctDNA) to evaluate stage III and stage IV metastatic breast cancer (MBC), describe tumor heterogeneity, and outcome [abstract 1028, online]. Poster presentation at the virtual scientific program of the American Society of Clinical Oncology, Alexandria, Va, May 29–31, 2020. J Clin Oncol.2020;38:(suppl):1028; doi: 10.1200/jco.2020.38.15_suppl.1028.