Mammograms are no longer recommended in New Zealand for women under the age of 50.
The policy, developed with the government and the Cancer Society of New Zealand, has resulted in the withdrawal of funding for screening for younger women.
Their controversial decision, at variance with the screening policies of most governments of developed countries, is supported by several studies that suggest mammography can actually spread cancer in the under-50 age group. This danger reduces in older women.
The National Cancer Institute of America has stated that no screening method-mammography, examination by a doctor or self-examination is effective in picking up signs of cancer in women under 50. Rather than arranging more trials to confirm this negative finding, the Institute says researchers should be focusing their efforts on primary prevention, identifying genetic markers and improving treatment (Journal of the National Cancer Institute, 1994; 86: 410-2).
Last November, the seventh European Conference on Clinical Oncology and Cancer Nursing heard that a breast cancer screening trial in Malmo showed a 25 per cent higher incidence of cancer among screened women than unscreened over a 10-year period.
Older women who lived near a chemical plant on Long Island, New York, in the US between 1965 and 1985 were 60 per cent more likely to develop breast cancer than women living elsewhere. A study by the New York State Department of Health said the risk was greatest among post-menopausal women who lived within one square kilometre of the plant. The two-year study investigated 1759 women who lived on Long Island for 20 consecutive years until 1985 (BMJ, 23 April 1994).
Pesticides like DDT could also be another environmental hazard triggering breast cancer. Several recent studies have shown a fourfold increase in the risk of developing breast cancer among women with high bodily levels of DDT. The US has controlled the use of DDT to levels 5000 per cent below that of other developed countries, although environmentalists fear these controls could be relaxed as the US approves the General Agreement on Tariffs and Trade (GATT) (JAMA, 20 April 1994).