In a study of 40 patients with high grade serous ovarian cancer, the researchers monitored tumour DNA that could be detected in a blood sample taken before each chemotherapy treatment. By measuring the levels of the mutated cancer gene TP53 they found those who responded well to treatment had a rapid fall in the levels of this circulating DNA.
The researchers tested levels of this circulating tumour DNA in patients before and after treatment. They found that it took longer for the disease to progress in patients whose tumour DNA count in the blood fell by more than a half after one cycle of chemotherapy, compared with patients whose DNA count did not drop. They also showed that the level of tumour DNA in the blood reflects the amount of cancer seen on scans carried out before chemotherapy.
This test may be particularly useful for patients with high grade serous ovarian cancer because the mutated cancer gene TP53 is found in more than 99 per cent of patients with this form of the disease. This type represents two thirds of all ovarian cancers.
Dr James Brenton, one of the lead authors of the study at the University of Cambridge, said: “There’s a need for a test to find out quickly whether ovarian cancer patients are benefiting from chemotherapy. These are early results, but if bigger trials are successful, this test looking at the tumour DNA circulating in the blood could be a cheap, quick and easy way to get this information.”
Professor Peter Johnson, Cancer Research UK’s chief clinician, said: “Although we’re making great progress, we still have more to do for people with ovarian cancer, as only one in three patients survive for 10 years or longer. Having a test to tell us early on whether chemotherapy is working would be a big help, and in the future might be a useful way to suggest other types of treatment that could work better. This could be a good way to test new types of drugs that target cancer cells specifically and spare patients the side effects from treatments if they are not working.”