Biennial mammography appears suitable for older women

In women who are at least 50 years of age, there is no increase in late-stage breast cancer when screening mammography is performed biennially rather than annually, new research shows. In contrast, in younger women, biennial screening is tied to an increased risk of late-stage disease.

“These findings may be useful for policy decisions about appropriate screening intervals and for use in statistical models that estimate the costs and benefits of mammography by age and screening interval,” lead study author Dr. Emily White, from the Fred Hutchinson Cancer Research Center in Seattle, and colleagues note.The findings, which appear in the Journal of the National Cancer Institute for December 15, are based on a study of women who were diagnosed with breast cancer after mammography screening intervals of 1 and 2 years. The former group included 5400 subjects and the latter included 2440.Among women in their 40s, the rates of late-stage breast cancer for annual- and biennial-screened subjects were 21% and 28%, respectively. This amounts to a 35% increased risk for biennial screening.As noted, the screening interval had no effect on the occurrence of late-stage disease in older women, the investigators point out.The authors also found no evidence that one type of interval was better than the other based on whether the breasts were dense or fatty. “To our knowledge, we are the first to report on this issue,” they write.”Our findings are generally consistent with those of previous studies,” Dr. White’s team concludes.(Source: J Natl Cancer Inst 2004;96:1832-1839: Reuters Health: Oncolink: December 2004.)