From Dailymail UK
Thousands of patients with an advanced form of bowel cancer may not need chemotherapy, scientists suggested today.
Just under a third of all bowel cancers are diagnosed at stage three, meaning it has spread into nearby lymph nodes but not other parts of the body.
Under current UK guidance, stage three treatment involves surgery to remove the tumour followed by chemotherapy to reduce the risk of the cancer returning.
But Australian researchers discovered that undertaking a ‘state-of-the-art’ blood test after surgery could determine if patients only need a reduced dose of chemotherapy or even no chemotherapy at all.
The test, known medically as a ctDNA test, looks for tiny fragments of tumour DNA circulating in the bloodstream.
Assessing patients who had ctDNA-negative results following surgery, scientists compared the outcomes of those who were given a reduced dose of chemotherapy or no chemo at all against those given standard treatment.
They found patients on the lower dose of treatment — mainly those with ‘low risk’ stage three tumours — dramatically reduced their risk of suffering side effects and some were at no higher risk of developing a more invasive form of the cancer.
Experts today, who labelled the findings ‘highly important’, said the test would ‘likely’ influence how patients are treated over the coming years, but warned that further research was vital.
It comes amid a disturbing rise in bowel cancer cases—also known as colon cancer—in under 50s has baffled doctors around the globe.
The disease—which also claimed the life of Dame Deborah James at the age of 40—has surged by 50 per cent this age-group over the past three decades.
In the groundbreaking trial, researchers tracked almost 1,000 patients with stage three bowel cancer who underwent a ctDNA test five or six weeks after surgery.
They found 702 were ctDNA-negative and of these 353 patients underwent reduced chemotherapy treatment.
Over a follow-up of three and a half years, they found just 6.2 per cent suffered severe side effects compared to 10.6 per cent on standard treatment.
Treatment-related hospitalisations were also lower, with 8.5 per cent requiring treatment compared to 13.2 per cent on standard treatment.
However, the results also showed that the ctDNA test alone was insufficient to determine which patients did not require chemotherapy without risking under-treatment.
But, a subgroup analysis of patients with low-risk stage three tumours — where only three lymph nodes were positive for the disease — found the approach was ‘non-inferior’.
Medically, this means a new treatment is not unacceptably worse than an existing one, even if it’s not proven to be more effective.
‘Stage three colon cancer patients with negative post-surgery ctDNA results had a low recurrence risk,’ the researchers from the Peter MacCallum Cancer Centre in Melbourne, said.
‘ctDNA guided de-escalation is feasible’, they added, ‘especially for clinical low-risk tumours’.
The results of the trial will be presented in full at the European Society of Medical Oncology annual congress in Berlin.
Professor Marco Gerlinger, a consultant medical oncologist at St Bartholomew’s Hospital in London, who was not involved in the research, also said: ‘A major problem in clinical practice is that we overtreat many patients, as 50 per cent have already been cured by surgery alone.
‘Until recently, we had no tests to identify those patients who don’t need chemotherapy.
‘This trial used a state-of-the-art high-sensitivity circulating tumour DNA test.
‘Although the trial is not practice changing for all stage three bowel cancers, it is highly important and will likely influence clinical practice.
‘For low-risk stage three tumours, patients may make an informed decision to omit or reduce chemotherapy intensity if the test comes back negative — as the trial showed that this reduces severe side effects.
‘But further trials are needed to confirm these results and to determine how circulating tumour DNA and other risk approaches need to be combined to tailor chemotherapy to the patient’s preferences and risk of recurrence.’
There are around 44,000 cases of bowel cancer every year in the UK and 142,000 in the US, making it the fourth most common cancer in both countries.
Symptoms often include changes in bowel movements such as consistent and new diarrhoea or constipation, needing or feeling the need to poo more or less frequently and blood in the stool.
Stomach pain, a lump in the stomach, bloating, unexpected weight-loss and fatigue are among other signs.
Anyone experiencing these symptoms should contact their GP for advice.
Although the vast majority of bowel cancer diagnoses affect those aged over 50, rates in older age-groups has either declined or held stable while diagnoses in younger adults have risen by 50 per cent over the last 30 years.
Cancer Research UK estimates that over half (54 per cent) of bowel cancer cases in the UK are preventable.
