Study: A simple blood test can help determine the strength of chemotherapy

For patients with colon or bladder cancer, a simple blood test could change the way doctors determine who needs chemotherapy and how aggressively, according to a study presented at the meeting of the European Society for Medical Oncology. More than 1,000 patients with stage III colon cancer from Australia, New Zealand and Canada participated in the study, from whom blood samples were taken about 6 weeks after undergoing surgery to remove the tumor. If no traces of cancer DNA are detected in the bloodstream, the disease is classified as “low risk”, while if such traces are present, it is considered “high risk”. The study, published in the journal Nature Medicine, explained that the blood test could give patients a more personalized treatment tailored to the level of risk, by determining who needs full intensity treatment, and who can be satisfied with lower doses. The results showed that patients whose condition was considered low risk achieved “excellent results”, as 87% of them remained cancer-free three years after surgery. The researchers said in a statement that patients whose condition was considered low-risk received less chemotherapy, leading to a decrease in hospital stays and side effects such as nerve damage. In contrast, the study showed that patients who had traces of cancer DNA in their bloodstream after surgery were more likely to get the disease back, with only half of them remaining cancer-free three years later. Intensive chemotherapy also did not improve outcomes in this group, indicating a need for new treatment strategies. 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, for patients who have had surgery to remove… Bladder tumors that have spread into muscle tissue. In turn, supervisor dr. Joaquim Palmon of the 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.” “This is the first time an adjuvant immunotherapy trial has shown a survival benefit in selected patients based on blood tumor DNA testing,” added Palmon.