Further evidence that breast screening for women aged under 50 is of little value has come from a Canadian study. Researchers there have found that mammograms may miss breast cancer if the woman is in the second half of her menstrual cycle, particula
Investigations are already under way in Britain into the affects HRT has on mammograms. Doctors fear it affects the sensitivity of the tests, as this new research suggests.
The study, carried out by a team from the University of Toronto, found that the mammograms were accurate in only 49 per cent of cases in women during the luteal phase days 15 to 28 of their cycle. Accuracy levels rose, but to only 60 per cent, among women in the first phase of their cycle. The difference in part explained the higher false negatives an "all clear" when there was cancer present among the women who were taking some hormonal therapy, such as the Pill and HRT.
But another contributing factor could be that breast tissue becomes more dense during the luteal phase, so reducing the sensitivity of the mammogram test.
Taking part in the study were 8,887 menstruating women aged between 40 and 44 (Cancer, 1997; 80: 720-4).