Experts said colostomy bags, to collect faeces, often frightened patients.
Globally, nearly 1.4 million cases of bowel cancer are diagnosed each year.
In the UK, more than a fifth of the cancers go undetected until the tumour blocks the intestines, leaving patients needing emergency surgery.
This unplanned surgery has a much higher risk of complications compared with routine surgery.
The patient is often in worse health, the swelling caused by the blockage can mean keyhole surgery is not possible so more invasive surgery is needed and there may not be a colorectal specialist surgeon on hand.
The death rate goes up from 2% for planned surgery to 12% in emergency bowel cancer surgery.
After removing the tumour and surrounding bowel, surgeons are also less likely to be able to re-plumb the bowels.
One part of the colon is often hugely distended and the other collapsing in on itself. If it cannot be put back together properly, the risk of needing a colostomy bag soars.
A trial on 250 patients was organised by Cancer Research UK. Half were treated with conventional surgery, but the others had a novel procedure to unblock the bowels.
Surgeons used an endoscope to find the precise location of the blockage and then positioned a stent at the site of obstruction.
When inserted, the tube is just 3mm in diameter. But over 48 hours it expands in response to body heat until it reaches 2.5cm in diameter, creating a new clear passageway through the intestines.
The tumour is then removed once the bowels have healed and the patient has recovered from the blockage.
There was no difference in survival rates between the procedures, but the difference in the need for a colostomy bag was stark.
In the emergency patients, 69% needed a bag to rid their bodies of faeces.
In those treated with the stent, the figure was 45%, according to data presented at the American Society of Clinical Oncology’s annual meeting in Chicago.
Prof James Hill, who led the trial at Central Manchester University Hospitals, said: “Traditionally doctors have worried that unblocking the bowel in this way could increase the chance of cancer spreading, but our early results don’t show this.
“We’re also pleased to see that this could be a way of reducing the risk of patients needing a colostomy bag after their surgery, which is a huge improvement to patients’ day-to-day lives.
“These are early results and we’ll need to follow up our work for three years in full to find out if this technique affects survival and end-of-life care for bowel cancer patients.”
Deborah Alsina, chief executive of Bowel Cancer UK, said the study appeared promising. “It is especially reassuring that stenting does not increase the chance of bowel cancer spreading,” she said.
“Whilst the majority of bowel cancer patients do not have a permanent stoma, for those who do it is possible to live well with one.
“It’s often an element of treatment that frightens patients most, so while we cautiously welcome the study, further long-term research is needed.”
Martin Ledwick, from Cancer Research UK, said: “This treatment isn’t suitable for everyone, but for those who are it could have a huge impact on their lives after surgery.
“Not needing a colostomy bag is likely to significantly improve the quality of life of patients.”