Cancer tests may do more harm than good
Expert says healthy living, not regular screening, is the best way to avoid disease
Regular cancer tests for people without any symptoms could do more harm than good, a medical expert warned yesterday.
Lam Tai-hing, chairman of an expert working group on cancer prevention and screening set up to review the effectiveness of cancer control in Hong Kong, said risks could spring from the side-effects of unnecessary X-rays and the stress of tests that falsely proved positive.
He made his warning in spite of an increase in the proportion of deaths resulting from cancers in Hong Kong, from 26.4 per cent in 1981 to 31.6 per cent in 2003.
Professor Lam said regular tests for detecting lung, colorectal, breast, liver and prostate cancers might do more harm than good for people who do not show cancer-related symptoms.
'Many people have a misconception that doing cancer tests regularly may ensure they are healthy, but it is not always the case,' he said.
People might suffer 'unnecessary worries' as relatively large numbers of people receive false-positive test results due to errors.
'For instance ... it is estimated that about 1,300 healthy women over 50 would need to be screened annually for 10 years to prevent just one cancer-related death. And [our study shows] 8,980 false-positive cases would be found in every 100,000 cases,' he said.
For prostate cancer, it was sometimes futile for men to undertake tests as cancer cells can vanish without treatment, he said.
'I therefore advise even old men without prostate cancer-related signs not to do the prostate cancer test because they might feel puzzled over whether to take medical action or leave it as it is,' said Professor Lam.
He also recommended people not to undertake X-ray examinations for detecting lung cancer cells because they might be exposed to potentially hazardous X-rays unnecessarily.
Professor Lam said Hong Kong had succeeded in controlling the incidence of lung cancer through an anti-smoking campaign. The incidence rate was down 28.5 per cent in 2001 compared with figures in 1983.
However, the incidence of diagnosed prostate and breast cancers cases surged, with prostate cancer rising 87.4 per cent and breast cancer up 29.5 per cent. Incidence of breast cancer in Hong Kong was quite high compared with other Asian countries, although it was still half less than that in western countries. Possible reasons for the increase might be the onset of earlier puberty, pregnancy at older ages and shortened breastfeeding duration, he said.
He recommended a healthy lifestyle such as eating more fresh vegetables and fruits, and reducing or giving up smoking as more effective measures to prevent cancer.