Background: Women with a personal history of breast cancer (PHBC) have increased risk of an interval cancer. We aimed to identify risk factors for second (ipsilateral or contralateral) screen-detected or interval breast cancer within 1 year of screening in PHBC women.
Methods: Screening mammograms from women with history of early-stage breast cancer at Breast Cancer Surveillance Consortium-affiliated facilities (1996-2008) were examined. Associations between woman-level, screen-level, and first cancer variables and the probability of a second breast cancer were modeled using multinomial logistic regression for three outcomes [screen-detected invasive breast cancer, interval invasive breast cancer, or ductal carcinoma in situ (DCIS)] relative to no second breast cancer.
Results: There were 697 second breast cancers, of these 240 were interval cancers, among 67,819 screens in 20,941 women. In separate models for women with DCIS or invasive first cancer, first breast cancer surgery predicted all three second breast cancer outcomes (P < 0.001), and high ORs for second breast cancers (between 1.95 and 4.82) were estimated for breast conservation without radiation (relative to mastectomy). In women with invasive first breast cancer, additional variables predicted risk (P < 0.05) for at least one of the three outcomes: first-degree family history, dense breasts, longer time between mammograms, young age at first breast cancer, first breast cancer stage, and adjuvant systemic therapy for first breast cancer; and risk of interval invasive breast cancer was highest in women <40 years at first breast cancer (OR, 3.41; 1.34-8.70), those with extremely dense breasts (OR, 2.55; 1.4-4.67), and those treated with breast conservation without radiation (OR, 2.67; 1.53-4.65).
Conclusion: Although the risk of a second breast cancer is modest, our models identify risk factors for interval second breast cancer in PHBC women.
Impact: Our findings may guide discussion and evaluations of tailored breast screening in PHBC women, and incorporating this information into clinical decision-making warrants further research.