Colon cancer patients could be spared chemotherapy thanks to a blood test that can determine whether surgery alone will target their tumor.
Currently, most patients with colon cancer are offered both treatments to prevent remnants of the disease from spreading again after surgery. But studies show that about half of these patients can be cured with surgery alone.
It means that some 16,000 people a year unnecessarily endure the debilitating side effects of chemotherapy, such as nausea, fatigue, infections, hair loss and permanent nerve damage.
Now oncologists at The Royal Marsden NHS Foundation Trust are testing a blood test that predicts the likelihood of cancer returning after surgery by detecting small fragments of tumor DNA.
Dame Deborah James, pictured, was undergoing chemotherapy as part of her treatment for colon cancer
More than 40,000 Britons are diagnosed with bowel cancer every year. It is the second biggest cancer killer, after lung cancer, largely because many cases are diagnosed at a late stage when it has spread to other parts of the body
Research shows that patients who have the DNA in their blood – called circulating tumor DNA – are much more likely to relapse within two years and should therefore undergo chemotherapy as well. Studies have also shown that the DNA can be spotted earlier than tumor growth can be detected by scans.
“We have a big problem with over-treating patients,” says Professor Lawrence Young, an expert in molecular oncology and director of Warwick University’s Cancer Research Center.
‘As soon as someone is diagnosed, we remove the tumor surgically, but there are big questions about whether or not to give chemotherapy. Most patients are given a mixture of nasty chemo drugs just to be on the safe side, but for many patients it is not necessary.
“These kinds of blood tests will revolutionize treatment, allowing doctors to confidently advise against chemo.”
Colon cancer campaigner and TV presenter Dame Deborah James, who died last June, graphically documented her own struggle with what she called “cruel chemotherapy.”
NHS hospitals have already trialled the blood test in lung and skin cancers and found it to be highly accurate in identifying patients most likely to relapse.
More than 40,000 Britons are diagnosed with bowel cancer every year. It is the second biggest cancer killer, after lung cancer, largely because many cases are diagnosed at a late stage when it has spread to other parts of the body.
‘Unfortunately, once colon cancer is in the blood, it can quickly spread to the liver, where it multiplies rapidly,’ says Prof. Young. Doctors do everything they can to prevent this, which usually involves a combination of powerful drugs.
“The standard treatment is a daily tablet called capecitabine and regular infusions of a stronger drug called oxaliplatin,” says Dr.
“But in four out of ten patients, oxaliplatin can cause debilitating, long-term nerve damage, so we can only use tablets in elderly or frail patients.”
Experts at Royal Marsden are offering 800 patients the new blood test after surgery, as part of a trial called TRACC. If no tumor DNA is detected, patients will either receive a weaker form of chemotherapy or no chemotherapy at all
“Patients who would otherwise have received the tablet alone are not given the drug, and those who would have been given the combination are simply given the tablet,” says Dr. Starling.
Dr. Starling and her team are now working on an economic analysis for the NHS drug watchdog, the National Institute for Health and Care Excellence (NICE).
She adds: “We think it will be great value for money given the cost savings by saving thousands of chemotherapy.”
One patient who benefits from this is 52-year-old Ben Cooke from London. The father-of-two was diagnosed with colon cancer in September and underwent surgery to remove part of his colon.
Within weeks he was given the opportunity to participate in the TRACC study. His circulating tumor DNA results were negative, so doctors recommended a less potent form of chemotherapy.
Ben, who finished his treatment last month, said: ‘Since starting treatment I feel absolutely fine and haven’t had to take a day off, which is great.
“Conventional chemo would put me at risk of nerve damage in my hands, which could affect my ability to do my job, so I’m thankful I’m not at risk for these side effects.”