Blood test could see some skip chemo

Cancer patients could avoid unnecessary chemotherapy with a blood test undergoing trials at 40 Australian and New Zealand hospitals, researchers have announced.

The “circulating tumour DNA” (ctDNA) test checks for pieces of cancer genetic material in the bloodstream, and the results can be used to sort patients into high- or low-risk groups, depending on the indicated chance of relapse. Currently, many post-operative cancer patients undergo chemotherapy, a harsh and intensive treatment, to mitigate their risk of the cancer recurring, but low-risk patients could skip the process.

“While chemotherapy is an essential, life-saving treatment, we don’t want patients receiving it if they don’t need it,” says Jeanne Tie, a clinician scientist at the Walter and Eliza Hall Institute (WEHI) in Melbourne, Australia, and the trial’s lead. “We want to help these patients avoid serious and ongoing side-effects associated with chemotherapy”.

Chemotherapy often comes with a slew of disagreeable short-term side-effects, including pain, fatigue, and nausea, but it can also cause long-term problems, including fertility issues, and heart, lung, nerve and memory deficits. A course of treatments can also can take months, causing patients to miss work and other parts of their normal lives.

That means people are keen to avoid the treatment, especially if it’s unnecessary.

“Avoiding the potential side-effects and inconvenience of chemotherapy was a huge relief – it meant I could get back to work quickly and continue to enjoy travel and social events”, says trial participant Hugh McDermott, who avoided chemotherapy after bowel surgery. “This test could potentially be enormously beneficial not only for patients and their doctors, but also for their family, friends, and carers”.

The trial began in 2015 with bowel cancer patients and was extended in 2017 to include some with ovarian cancer. So far, 400 people have participated, and researchers are hoping to test another 1600 with bowel or ovarian cancer before the process ends in 2021. The test was developed in collaboration with the Johns Hopkins Kimmel Cancer Centre in the US.

ctDNA tests are gaining utility across cancer treatments. Another clinical trial, conducted in Philadelphia, recently found that the blood tests were more accurate than biopsies for identifying cancer mutations. 

Blood tests are also less invasive than biopsies, which take tissue directly from the tumour site.

In that trial, ctDNA tests in patients with non-small cell lung cancer (NSCLC) found significantly more mutations than biopsies alone, the researchers found.

“These findings show that liquid biopsy is increasing the detection of mutations we can target and improving patient outcomes,”,says the study’s co-lead author Charu Aggarwal from the University of Pennsylvania.

“And when you combine that with the reality that liquid biopsy is less invasive for patients and, in some cases, may be the only option for patients, the clinical impact is very clear.”