"We only want to use chemotherapy where we think there's a good chance it will help. This test will help use determine that," said co-author Robert Wilson, a surgeon at The James Cook University Hospital in Middlesbrough, England.
Colorectal, or bowel, cancer is the third most deadly form of cancer worldwide, accounting for nearly 680,000 deaths in 2007, according to the World Health Organisation.
Almost three-quarters of all cases -- linked to diet and lifestyle -- occur in people aged 65 and over.
"There is a desperate need for more effective treatments for bowel cancer," noted Mark Matfield of the Association for International Cancer Research, commenting on the study.
"The problem is identifying which cancers need which treatment. This discovery may show us the way to do that and help save a lot of lives," he said.
Stem-cell researchers led by Christopher Hutchison of Durham University examined tissue samples from 700 bowel cancer patients.
They found that patients who had a stem cell marker protein called "Lamin A" were more likely to have an especially aggressive and tenacious form of the disease.
If detected in the early stages of the cancer's progression, the marker could signal the need for chemotherapy in addition to the more standard use of surgery to remove tumours, they concluded.
Scientists identify four stages in the development of bowel cancer. In the first two stages -- before patients develop lymph nodes -- patients normally have an operation to remove cancerous tissue.
They are rarely given chemotherapy, which can sometimes cause more harm then benefit.
But the new study shows that one third of these patients will express the Lamin A stem cell marker, and would thus be good candidates for the more aggressive form of treatment.
The study was published in the open-access science journal Public Library of Science One (PLoS One).