The US Preventive Services Task Force's recent change to its mammography screening guidelines may prevent women in their 40's, and specifically minority women, from receiving early breast cancer diagnoses, two new studies suggest.
The USPSTF no longer advises women in their 40s to get routine screening mammograms.
But one of the two studies, a 10-year retrospective analysis from the University of Missouri in Columbia, showed that mammography detected smaller tumours with less nodal metastasis than manual breast exams in women in their forties.
And minority women were more likely to develop cancers in their 40's than white women, according data from the California Cancer Registry reviewed by researchers at Loma Linda University.
Both research teams presented their results at the annual meeting of the American Society of Breast Surgeons in Washington, DC last week.
The studies show two angles of the same issue, said Dr Sheldon Feldman, chief of breast surgery at Columbia University Medical Centre in New York and Chair of the society's publication committee.
Dr Feldman, who was not involved in either study, said, "For some Asian women and other minorities, the peak incidence is a decade earlier. The guidelines are not ethnicity-specific."
"And that's an important point," he added. "Whether or not you agree with the general recommendations for average groups, then certainly for minorities and certain subgroups, those recommendations need to be altered."
Breast cancer patients
Researchers at the University of Missouri reviewed data on 1,581 breast cancer patients and identified 311 who were aged 40-49, including145 (47%) who were diagnosed with a mammogram.
The median tumour diameter was 20 mm in the mammogram group, compared to 30 mm in the non-mammogram group (P<0.0001).
Women in the mammogram group had a lower rate of lymph-node positive cancer (25% vs. 56%, P=0.0001). And, five years after diagnosis, women in the mammogram group were more likely to be free of disease (94% vs. 71%) and had a better overall survival rate (97% vs. 78%).
Multivariate analysis found that detection by mammography, node negativity and smaller tumour size were associated with a significant increase in the rate of survival.
"Breast cancer has a better prognosis when treated before tumours become palpable and identifiable through a physician or self-breast exam," Dr Paul Dale, who led the research, said in a statement. He strongly advocates a change in the USPSTF guidelines.
Minorities seem to make up a disproportionate number of the younger women who might benefit from mammography screening, a separate study found.
Dr Sharon Lum and her team at Loma Linda University identified 46,691 patients ages 40 to 74 who were diagnosed with ductal carcinoma in situ (DCIS) or T1N0 breast cancer from 2004 to 2008.
They divided the women by age and race: 22.6% were ages 40 to 49, 65.5% were non-Hispanic white, 15% were Hispanic, 12.8% were Asian and Pacific Islander, and 5.4% were non-Hispanic black.
Among the women in their 40's, some minority groups were more likely than white women to have DCIS or T1N0 diagnoses. Hispanics were most likely to have DCIS (odd ratio 1.62) and T1N0 (OR: 1.82). Asians and Pacific Islanders followed in DCIS diagnoses (OR: 1.5) and T1N0 (OR: 1.66). Non-Hispanic black women had fewer DCIS diagnoses (OR: 0.91) and more T1N0 diagnoses (OR: 1.44).
"The lower likelihood of diagnosing DCIS in non-Hispanic black women may be related to delayed access to screening and care or earlier onset of invasive disease," Dr Lum and her team wrote in their abstract.
"The implementation of the USPSTF recommendations would disproportionately impact non-white women and potentially lead to more advanced presentation at diagnosis," the researchers note, adding that further investigation is needed.
(Reuters Health, Rob Goodier, May 2011)