Blood test predicts which prostate cancer patients are resistant to chemotherapy drug

Nov. 18, 2021

Research conducted at Queen Mary University of London indicates that regular blood tests before and during chemotherapy for prostate cancer can detect whether a patient is resistant or developing resistance to treatment with a drug, according to a news release from the school.

Docetaxel is a chemotherapy often used to treat men with prostate cancer that has started to spread to other parts of the body (metastasized) and does not respond to therapy to lower levels of the hormone androgen. Docetaxel can significantly improve survival; however, some patients are resistant or acquire resistance to the drug.

The team collected and analyzed circulating tumor cells (CTCs) using liquid biopsy in blood samples taken from 56 patients with advanced prostate cancer who were being treated at St Bartholomew’s Hospital in London. The samples were collected before, during and after treatment with docetaxel, which allowed the researchers to monitor changes in CTCs in response to treatment.

The team looked for patterns in the data from patients who responded to treatment or did not, or whose cancer progressed sooner than others’ did after treatment.

The researchers found that if more than six CTCs per 7.5mL of blood were detected before the first docetaxel dose, patients were less likely to respond to docetaxel, their disease was more likely to recur or progress within three months, and they were more likely to die within 18 months. This compared to progression-free survival of 17 months and an overall survival time of three years for patients with fewer than six CTCs detected per 7.5mL of blood.

The team also found that the type of CTCs present within the blood samples could predict disease progression and survival, and that high numbers of CTCs towards the end of treatment predicted a shorter time to cancer progression and death.

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