Women between the ages of 40 and 49 years who underwent routine screening mammography were diagnosed at earlier stages with smaller tumors than symptomatic women requiring diagnostic workup, according to a study published in the May issue of American Journal of Roentgenology.
In the U.S., screening mammography exists in a state of flux for women between the ages of 40 and 49. The U.S. Preventive Services Task Force (USPSTF) recommends against annual screening mammography for this group of women. In contrast, the American Cancer Society, American College of Radiology and other professional societies recommend annual exams beginning at age 40.
Mallory E. Kremer, MD, from Case Western University School of Medicine in Cleveland, and colleagues sought to compare breast cancer stage at diagnosis among two groups of women between the ages of 40 and 49: women undergoing screening mammography and women presenting with a specific breast complaint who needed a diagnostic examination.
The researchers completed a retrospective chart review of all women between the ages of 40 and 49 who underwent image-guided breast biopsies at breast centers at University Hospitals Case Medical Center from January 1, 2008, to December 31, 2009. They categorized biopsy-proven cancers as either noninvasive ductal carcinoma in situ (DCIS) or invasive cancer.
Of the 493 women who underwent image-guided biopsies, 108 patients with primary breast cancers were included in the analysis. A total of 71 cancers were diagnosed in the screened group and 37 were found in the unscreened cohort. Twenty-one percent of women were diagnosed with DCIS and 79 percent with invasive cancer.
Women in the screened group were significantly more likely to be diagnosed with DCIS than those in the unscreened group, and invasive disease was more frequently diagnosed at an earlier stage in the unscreened group. Invasive cancers in screened women were more likely to be smaller than 2 centimeters.
A fellowship-trained radiologist completed a secondary review of the 17 screened women who presented with an interval cancer. “All but one of the 17 women had more than 50 percent density on mammography and were imaged on outside-institution film-screen mammography,” wrote Kremer et al.
The researchers described the results as “provocative” and suggestive “of a real benefit from screening women ages 40-49 years.”
Kremer and colleagues acknowledged the challenges of DCIS, which now accounts for 20-25 percent of screen-detected cancers, and noted that physicians are unsure which DCIS lesions will progress to invasive breast cancers. Although critics have suggested that some DCIS will never progress to invasive disease, the current standard of care treats DCIS as a malignancy.
The researchers listed multiple benefits associated with diagnosis at stage 1 and with smaller tumor size. These include a 100 percent 5-year relative survival rate and potential avoidance of side effects of treating higher stage disease, such as chemotherapy, mastectomy, node dissection and chest wall radiation.
Finally, Kremer and colleagues disputed the potential harms of benign and unnecessary biopsies, which the USPSTF cited as a reason for its recommendations. “Included in this group are a number of high-risk lesions discovered by imaging-guided breast biopsy.” Patients with high-risk lesions—32 percent in the current study—can benefit from close follow-up, chemoprevention or heightened screening, according to the researchers, which may deliver long-term benefits. “Biopsies yielding information about high-risk lesions can be considered a potential asset and not a detriment to a screening program,” wrote Kremer et al.
The researchers summed, “Contrary to the 2009 USPSTF guidelines, we continue to support screening mammography in women between the ages of 40 and 49 years.”