A team of researchers has found that measuring the concentration of circulating tumor DNA in the blood of ovarian cancer patients can predict the chance of treatment success. The information gained from these blood tests can allow physicians to estimate the size and severity of the cancer. Measuring this type of DNA can also help doctors predict how a patient might respond to chemotherapy. The findings are in a paper that was just published in the journal PLOS Medicine.
Circulating tumor DNA (ctDNA) is DNA that originated from a tumor and is now floating throughout the patient’s bloodstream. This DNA will vary from the patient’s normal DNA samples because the ctDNA will carry the mutations that originally led to cancer. Currently, doctors use CA-125 levels (proteins associated with severe ovarian cancer) to determine how well a treatment is working. The problem with this method is that CA-125 levels take a long time to change and don’t always provide a complete picture of disease progression. If ctDNA could be used instead of CA-125 concentrations, doctors might gain more accurate information.
The majority (over 99%) of patients with severe ovarian cancer, also called high grade serous ovarian cancer (HGSOC), have ctDNA with a mutation in the TP53 gene. The research team collected blood samples from 40 HGSOC patients before, during, and after cancer treatment. The researchers found that as the concentration of mutated ctDNA increased, the disease progressed. There was also correlation between ctDNA concentrations and future response to treatments. Patients with lower levels of mutated ctDNA responded better to chemotherapy and their cancer progressed slowly. The team acknowledged that their sample size was small but that ctDNA shows promise as a measure of disease progression. Measuring ctDNA can also predict a patient’s response to chemotherapy and other treatments.
The team’s results suggest that ctDNA blood tests may be more useful than the current CA-125 tests. By measuring mutated ctDNA, scientists can determine the progression of ovarian cancer and how likely a patient is to positively respond to chemotherapy. The team recommends further investigation of ctDNA as a measure of disease progression and treatment response.
Parkinson et al. Exploratory Analysis of TP53 Mutations in Circulating Tumour DNA as Biomarkers of Treatment Response for Patients with Relapsed High-Grade Serous Ovarian Carcinoma: A Retrospective Study. PLOS Medicine (2016).