Mammograms Less Sensitive in Breast Cancer Survivors

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Women with a personal history of breast cancer (PHBC) are at risk of developing another breast cancer. Current recommendations are for annual screening mammograms which according to a new study published in the Feb. 23 issue of the Journal of the American Medical Association are not as helpful in detecting new cancers as in women with no history of past breast cancer.

Women with PHBC are at risk of developing second breast cancers, which can be ipsilateral (in the same breast as a recurrence or new cancer) or contralateral (the other breast). This risk of a second breast cancer has been estimated at 5.4 to 6.6 per 1000 woman-years.

Nehmat Houssami, MBBS, PhD, of the University of Sydney, and colleagues conducted their study to examine the accuracy and outcomes of mammography screening in PHBC women relative to screening of similar women without PHBC.

To do this Houssami and her colleagues looked at screening results from women who had mammographies from 1996 to 2007 through facilities affiliated with the Breast Cancer Surveillance Consortium.

The researchers analysis included 58,870 screening mammograms in 19,078 women with a history of early-stage (in situ or stage I-II invasive) breast cancer and 58,870 matched screening mammograms for breast density, age group, mammography year, and registry in 55,315 non-PHBC women.

There were 655 cancers (499 invasive and 156 in situ) in the patients with a cancer history, and 342 (285 invasive and 57 in situ) in the controls within one year after screening.

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Per 1,000 screens, the rates of all breast cancers (10.5 versus 5.8), true-positive results (6.8 versus 4.4), and interval cancers (3.6 versus 1.4) were significantly higher in the women with a history of breast cancer (P

Mammography was less sensitive in women with a personal history of breast cancer (65.4% versus 76.5%, P

Screening sensitivity in PHBC women was higher for detection of in situ cancer (78.7%) than invasive cancer (61.1%).

Screening sensitivity in PHBC women was lower in the initial 5 years (60.2%) than after 5 years from first cancer (70.8%).

Screening sensitivity in PHBC women was similar for detection of ipsilateral cancer (66.3%) and contralateral cancer (66.1%).

Screen-detected and interval cancers in both women with and without PHBC were predominantly early stage.

Mammography was shown to have lower sensitivity in certain subgroups of women with a personal history of breast cancer, including those younger than 50, those with denser breasts, and those who received chemotherapy for their first cancer diagnosis.

Source reference:
Houssami N, et al "Accuracy and outcomes of screening mammography in women with a personal history of early-stage breast cancer" JAMA 2011; 305: 790-799.

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