WASHINGTON – The revised national screening mammography guidelines may especially impact the health of younger minority women for whom annual screening is no longer recommended, investigators suggested.
A retrospective study derived from a large state cancer registry found that Hispanic, Asian, and black women aged 40-49 years were up to 60% more likely to be diagnosed with ductal cancer in situ (DCIS) and up to 80% more like to have small invasive breast tumors (T1N0) than were their white counterparts.
These women were significantly more likely to have tumors that respond best to very early therapy, Dr. Sharon Lum said at the annual meeting of the American Society of Breast Surgeons. But if their cancers are not detected through mammography, women in these groups might not receive such therapy.
"We already know that breast cancer occurs at a younger age in minorities, and that minority women present with later-stage breast tumors and they have poorer survival, "said Dr. Lum of Loma Linda (Calif.) University. "Yet under the new guidelines, the diagnosis of patients such as these would be delayed until they developed larger tumors evident though manual breast exams. Now, through our study, we know that minority women fall into these categories in a higher percentage" than do white women.
Dr. Lum presented an analysis of the California Cancer Registry, focusing on 46,691 women aged 40-74 years who were diagnosed with DCIS or T1N0 tumors in 2004-2008. She and her colleagues divided the women into two age groups: 40-49 years (23%), for whom annual screening mammograms are no longer recommended by the U.S. Preventive Services Task Force (USPSTF), and 50-74 years (77%), for whom the annual screening recommendation has not changed.
The patients were further subdivided into four race/ethnicity groups: white (65%), Hispanic (15%), Asian/Pacific Islander (13%) and black (5%). Ethnicity was not specified for the remainder of the study group.
Overall, there were 16,067 cases of DCIS and 30,624 T1N0 tumors in the group. Compared with white women, Hispanic women were significantly more likely to have DCIS (odds ratio, 1.62) and T1N0 tumors (OR, 1.82). Women of Asian/Pacific Island descent had a 50% increased risk of DCIS and a 66% increased risk of T1N0 disease, compared with white women. Black women were significantly more likely than whites to have T1N0 cancers (OR, 1.44), but not more likely to have DCIS (OR, 0.0.91).
Age also made a difference, Dr. Lum found. Compared with older women, the younger women were significantly more likely to have hormone receptor–positive DCIS (OR, 1.85) and T1N0 disease (OR, 1.43). Younger women were also more likely to have HER2-positive T1N0 tumors (OR, 1.46), and were 67% more likely to have the difficult-to-treat triple-negative tumors.
The molecular findings argue strongly in favor of regular screening mammograms for younger women – especially minority women, Dr. Lum said. Hormone receptor–positive tumors and HER2-positive tumors have highly effective, targeted therapies. And although triple-negative tumors are a therapeutic challenge, the best curative chance lies with early treatment, she said.
"By excluding these younger women from mammographic screening, you may be relatively diminishing the benefits of these targeted therapies," she said. "And while younger women do have lower cancer rates than older women, under these USPSTF guidelines, we could miss tremendous opportunities to improve outcomes in specific racial and disease groups."
Dr. Lum had no financial declarations with regard to her study.