Heart disease patients at greater risk of bowel cancer, say experts
Heart disease patients should get tested for bowel cancer as they have a higher risk of contracting the disease, said medical researchers on Thursday.
Among those who have coronary heart disease or are at risk of having coronary heart disease, 40 per cent have pre-cancerous bowel tumours, a study by the Chinese University found.
“Coronary heart disease and bowel cancer, both being top killers, share mostly the same risk factors. But the two are seldom considered side by side,” said Professor Chan Ka-leung, dean of the university’s faculty of medicine who specialises in digestive diseases.
Obesity, high blood pressure, diabetes, smoking, being male and being over age 50 are risk factors shared by the two diseases.
Many heart disease patients taking anti-platelet drugs, designed to prevent the formation of blood clots, are reluctant to undergo tests for other diseases due to the risk of bleeding during the colonoscopy procedure.
Chan assured heart disease patients that the testing procedure is safe for those taking anti-platelet drugs, as long as tests are carried out by an experienced doctor.
The university’s Institute of Digestive Diseases is offering free colonoscopies to coronary heart disease patients who are taking the Plavix anti-platelet drug from now till the end of May.
Chan urged heart disease patients to be tested since early discovery and removal of precancerous tumours would prevent bowel cancer from developing. These tumours, or polyps, can be removed during colonoscopy and no surgery is needed.
Moreover, in advanced bowel cancer cases, risks associated with cancer tumour removal surgery increase in heart disease patients due to the medication they are taking.
In the university’s bowel cancer screening project for people aged 50 to 70, in the past five years 439 people have or are at risk of developing coronary heart disease and 3,024 were healthy. People with no symptoms but who exhibit many of the risk factors are considered at risk.
Among the former group, 40 per cent were found to have pre-cancerous bowel tumours compared to 29 per cent in the healthy group.
Bowel cancer was found in one per cent of those in the heart disease group and 0.4 per cent of the healthy group.
So far, no mutual causation relationship between the two diseases has been identified but the findings can be explained by the two having similar causes.
“The tradition of cardiac specialists considering only the heart, and gastroenterologists considering only the digestive system has to change,” said Chan. He called for more cooperation between different specialities.
Bowel cancer is the second most common cancer in Hong Kong, causing more than 1,700 deaths in 2009. Heart disease is the second most common killer disease in Hong Kong after cancer, according to government figures.