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A simple and safe way of analysing the activity of colon cancer cells
could help doctors to predict whether the disease is likely to recur after
surgery. People at risk could then be given preventive anticancer drugs.

A research team led by Ibrahim Al-Sheneber, a surgeon at McGill University
and the Royal Victoria Hospital in Montreal has found a protein that was
significantly higher in specimens of colon tissue from people who later
died from colon cancer than in people who survived for five or more years.
The protein, known as proliferating cell nuclear antigen, or PCNA, is associated
with cell division. To identify the protein, the researchers used a monoclonal
antibody which ‘recognised’ only PCNA.

According to Al-Sheneber, doctors tend to believe that people who have
undergone surgery to remove colon cancer will be cured. ‘However, between
40 and 50 per cent of these patients come back again with metastasis or
recurrence of the disease,’ he says.

Al-Sheneber and his colleagues examined the tissue samples and medical
records of 40 patients who had part of their colon removed because of cancer.
They looked at both cancer cells and normal tissue from the colon, and used
a ‘proliferation index’ to describe the amount of PCNA in the cells. They
found that in people who died of colon cancer both cancerous and normal
cells had a higher proliferation index.

Colon cancer is ‘staged’ according to the Dukes staging method, which
categorises colon cancer into stages A, B, C and D, with A signifying the
least serious form of the disease. Al-Sheneber believes that PCNA analysis
could provide a better prediction of the outcome of the disease. Surgeons
removing cancerous tissue could ask the pathologist to tell them the proliferation
index in addition to the Dukes stage.

Al-Sheneber cautions that it is still too early to decide on treatment
solely on the proliferation index. ‘This is the first paper to show the
relationship between cell proliferation and survival in colorectal cancer
patients, and it included only 40 patients,’ he says. ‘We need to study
more patients.