Abstract
Purpose The aim of the current study was to characterize the risk of interval invasive second breast cancers within 5 years of primary breast cancer treatment. Methods We examined 65,084 surveillance mammograms from 18,366 women with a primary breast cancer diagnosis of unilateral ductal carcinoma in situ or stage I to III invasive breast carcinoma performed from 1996 to 2012 in the Breast Cancer Surveillance Consortium. Interval invasive breast cancer was defined as ipsilateral or contralateral cancer diagnosed within 1 year after a negative surveillance mammogram. Discrete-time survival models-adjusted for all covariates-were used to estimate the probability of interval invasive cancer, given the risk factors for each surveillance round, and aggregated across rounds to estimate the 5-year cumulative probability of interval invasive cancer. Results We observed 474 surveillance-detected cancers-334 invasive and 140 ductal carcinoma in situ-and 186 interval invasive cancers which yielded a cancer detection rate of 7.3 per 1,000 examinations (95% CI, 6.6 to 8.0) and an interval invasive cancer rate of 2.9 per 1,000 examinations (95% CI, 2.5 to 3.3). Median cumulative 5-year interval cancer risk was 1.4% (interquartile range, 0.8% to 2.3%; 10th to 90th percentile range, 0.5% to 3.7%), and 15% of women had ≥ 3% 5-year interval invasive cancer risk. Cumulative 5-year interval cancer risk was highest for women with estrogen receptor- and progesterone receptor-negative primary breast cancer (2.6%; 95% CI, 1.7% to 3.5%), interval cancer presentation at primary diagnosis (2.2%; 95% CI, 1.5% to 2.9%), and breast conservation without radiation (1.8%; 95% CI, 1.1% to 2.4%). Conclusion Risk of interval invasive second breast cancer varies across women and is influenced by characteristics that can be measured at initial diagnosis, treatment, and imaging. Risk prediction models that evaluate the risk of cancers not detected by surveillance mammography should be developed to inform discussions of tailored surveillance.
Highlights
Breast cancer screening and treatment are increasingly tailored to women’s risks, but imaging surveillance after primary breast cancer (PBC) treatment remains a one-size-fits-all approach
Cumulative 5-year interval cancer risk was highest for women with estrogen receptor– and progesterone receptor–negative primary breast cancer (2.6%; 95% CI, 1.7% to 3.5%), interval cancer presentation at primary diagnosis (2.2%; 95% CI, 1.5% to 2.9%), and breast conservation without radiation (1.8%; 95% CI, 1.1% to 2.4%)
Risk of interval invasive second breast cancer varies across women and is influenced by characteristics that can be measured at initial diagnosis, treatment, and imaging
Summary
Breast cancer screening and treatment are increasingly tailored to women’s risks, but imaging surveillance after primary breast cancer (PBC) treatment remains a one-size-fits-all approach. Risk-based surveillance offers the potential to further tailor the use of imaging and improve outcomes for women with a personal history of breast cancer by focusing supplemental imaging on women who are at increased risk of an adverse surveillance outcome with mammography alone— an interval invasive second breast cancer diagnosed within 1 year of a negative mammogram. These interval cancers have been reported to represent approximately 35% of invasive second breast cancers in either the index or contralateral breast.[6,7] Considerations for reducing the incidence of interval invasive second breast cancer events that have been considered include interventions to improve the primary treatment of initial breast cancer and more intensive surveillance imaging regimens.
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