Older women with an extended period of time between their last mammogram and breast cancer diagnosis have an increased risk of death from the disease, according to data presented at the American Association for Cancer Research (AACR) annual meeting in Washington, DC. The findings suggest a role for continued mammography screening among women older than 75.
Mammography screening recommendations tend not to include this age group. In fact, the 2009 U.S. Preventive Services Task Force (USPSTF) statement on breast cancer screening indicated there was little evidence that women older than 75 benefit from regular screening, based on the assumption that the disease grows slowly in this population.
Dr. Michael Simon from Barbara Ann Karmanos Cancer Institute.However, data from the National Institutes of Health (NIH) Women's Health Initiative run contrary to this recommendation, according to lead researcher Dr. Michael Simon, from the Barbara Ann Karmanos Cancer Institute, and colleagues. More than 60% of breast cancers diagnosed among those ages 75 and older in the Women's Health Initiative were moderately or poorly differentiated, suggesting they were more aggressive and could potentially benefit from treatment.
"We found that for women age 75 and older, a longer time interval between the last mammogram and the date of breast cancer diagnosis was associated with a greater chance for dying from breast cancer," Simon told AuntMinnie.com. "We're not only seeing indolent cancers among older women. It's still worth treating older women."
Simon's team collected data from 9,929 women in the Women's Health Initiative who had been diagnosed with breast cancer during a 12.2-year follow-up.
An interval of five or more years between a woman's last mammogram and breast cancer diagnosis was associated with advanced-stage disease in 23% of women, compared with 20% of women with an interval of six months to a year, Simon said.
"We found that the older women who had not had a mammogram in five or more years had a threefold increased risk of dying of breast cancer compared to women who had a mammogram within six to 12 months of diagnosis," Simon told AuntMinnie.com.
The relationship between mortality and screening mammography interval was not found among younger women, according to the researchers.
"I am not sure why we are seeing these results, particularly for older women," Simon said in a statement released by AACR. "Tumors of younger women were more likely to be a little more unfavorable overall. It is possible that the differences in the relationship between screening interval and mortality in older versus younger women may be related to the more aggressive nature of the tumors in younger women, which might obliterate the effects of more screening. Other reasons may include differences in cancer treatment, information that was not available for this cohort of women."
What do the findings suggest in terms of clinical practice? Regular mammography should be continued for older women every one or two years; however, as with younger women, mammography screening should be considered in light of the overall health of the individual, Simon said.
"Women aged 75 and older are still working, traveling, enjoying their families," he told AuntMinnie.com. "We can't just tell them to stop getting screened."
