The results of a study presented at the European Society of Medical Oncology meeting revealed that a simple blood test could change the way doctors determine who needs chemotherapy and how strong it is for patients with colon or bladder cancer.
In one study, blood samples were taken from more than a thousand patients with stage III colon cancer about 6 weeks after they underwent surgery to remove the tumor.
If traces of cancer DNA are not detected in the bloodstream, the disease is classified as “low risk,” but if these traces are present, it is considered “high risk.”
A report on the study published in the journal Nature Medicine stated that the results of tumor DNA in the blood determine the strength of treatment required for each patient.
The researchers said in a statement that patients whose condition was considered low-risk received less chemotherapy, which led to a decrease in hospital stays and side effects such as nerve damage.
The researchers said, “The results were excellent among patients whose condition was classified as low risk based on the levels of tumor DNA in the blood, as 87% of them remained cancer-free for 3 years after surgery.”
A separate international trial published in the New England Journal of Medicine found that blood tests for tumor DNA in the bloodstream can also help guide treatment with Tecentriq (atezolizumab), an immunotherapy from Roche Pharmaceuticals, for patients who have undergone surgery to remove bladder tumors that have extended into muscle tissue.
The head of the study, Dr. Joaquim Palmon from the American Dana-Farber Foundation, said in a statement: “By selecting patients based on the tumor DNA circulating in the bloodstream, we see a benefit not only for disease-free survival, but also for overall survival using (the drug) Tecentriq.”
He added, “This is the first time that an adjuvant immunotherapy trial has shown a survival benefit for selected patients based on blood tumor DNA testing.”