Lifestyle 'trap' prevents cut in breast cancer

CHANGES IN lifestyle to reduce the high risk of breast cancer among women in affluent Western countries 'may not be feasible' according to American researchers.

In a study of the risks of getting breast cancer and of dying from it, involving nearly 100 international surveys, the researchers say: 'It is either impossible or culturally unacceptable to modify some of the clearly established risk factors.'

Women's weight, height, race, quality of diet, use of hormones as contraceptives or replacement therapy, numbers of children and family histories of breast cancer are all factors, the researchers say in the current issue of The New England Journal of Medicine.

The study is one of three to assess doctors' progress with a disease which is increasing, although the death rate is falling. Breast cancer is the leading cause of death among middle-aged women in Western countries.

The American researchers are led by Dr Jay Harris of the Harvard Joint Center for Radiation Therapy, Boston, Massachusetts. He says that since changing the factors that put women at risk may be impossible, scientists will have to work harder at teasing out the factors that can be modified.

'Prevention may depend on the artificial manipulation of hormones and growth regulators that underlie the known risk predictors, such as the woman's age at the birth of her first child and at menopause,' he says.

The current scientific understanding of causes is poor, the Americans say. But research has shown that women who do not have children, and women who have their first children after the age of 30, have an increased risk of breast cancer, though the risk for childless women appears to decrease in later life.

'The risk of breast cancer among women who have their first child after the age of 30 is about twice as high as that among those who have their first child before the age of 20,' they say. Women who have their first child after 35 run a bigger risk than women who do not have children.

Obesity does not increase risk - in pre-menopausal women it seems to reduce it - but being tall is associated with a higher chance of the disease.

Seeking explanations for the apparent increase in cases the researchers say that hormone supplements, such as the Pill and hormone replacement therapy (HRT), play some part.

While the the Pill appears to increase risk by 50 per cent, they say that this risk drops again rapidly once women stop taking it.

Similarly HRT appears to increase the risk of breast cancer by 40 per cent in women taking it, but the risk diminishes when they stop.

One explanation for a greater evidence of risk for older women on HRT is that they are likely to have been taking it for longer.

On screening for breast cancer, the researchers say that not all of the decrease in the death rate can be accounted for by better and earlier detection of the disease and advances in treatment. They suggest that a less aggressive type of cancer which depends on the female hormone oestrogen may be on the increase.

While there is continuing debate over the ability of national breast cancer screening programmes to reduce death rates, and arguments over the best age at which to start screening, the American researchers say that, overall, breast cancer screening will reduce the mortality rate by 25 per cent.

'Some have argued that this is likely to be a conservative estimate . . . as all the studies have some limitations that would tend to reduce the observed benefit.'

They say that there is no evidence that screening younger women, between 40 and 49, has any impact on death rates. In Britain women are offered a breast

X-ray every three years between the ages of 50 and 64.