Risk Factors for Interval Invasive Second Breast Cancer
In a study reported in the Journal of the National Cancer Institute, Lee et al found that factors associated with an increased risk of interval second breast cancers after negative surveillance mammography included grade II primary breast cancer, lumpectomy without radiation, interval primary cancer presentation, and heterogeneously dense breasts on mammography.
Study Details
In the study, the 5-year risk of interval invasive second breast cancer was analyzed in a prospective cohort of 15,114 women with 47,717 surveillance mammograms diagnosed with stage 0 to II unilateral primary breast cancer between 1996 and 2008 at sites in the Breast Cancer Surveillance Consortium. Second breast cancers were defined as ductal carcinoma in situ or invasive breast cancer in the index or contralateral breast identified within 12 months of a surveillance mammogram and prior to the next surveillance mammogram by either tumor registry or institutional pathology data. An interval invasive second cancer was defined as an invasive second cancer observed after initial surveillance mammogram with negative results.
Risk Factors
The cumulative 5-year incidence of second breast cancers was 54.4 per 1,000 women, with 325 surveillance-detected and 138 invasive interval second breast cancers being observed. On multivariate analysis, grade II primary cancer (odds ratio [OR] = 1.95, P = .014, vs grade I), treatment with lumpectomy with radiation (OR = 2.13, P = .001) or without radiation (OR = 3.27, P <.001) vs mastectomy, primary cancer interval presentation (OR = 2.01, P = .002) or clinical/diagnostic detection (OR = 2.12, P = .003) vs screen detection, and heterogeneously dense breasts on mammography (OR = 1.54, P = .045, vs scattered fibroglandular tissue) were independent predictors of invasive interval second breast cancers. In the fully adjusted multivariate model, age at diagnosis, hormone receptor status, and first-degree family history were not significant predictors of interval invasive breast cancer.
Risk Profiles
The five-year risk of interval invasive second cancer for a woman with reference category characteristics for all predictors was 0.60%. In comparison, the risk was 0.07% for a woman with the most favorable characteristics (eg, screen-detected primary, grade I, treated with mastectomy, and fatty breast tissue on mammography) and 6.11% for a woman with the least favorable characteristics (eg, clinically detected primary, grade II, treated with lumpectomy without radiation therapy, and extremely dense breast tissue on mammography).
The investigators concluded: “[Primary breast cancer diagnosis] and treatment characteristics contribute to variation in subsequent-interval second breast cancer risk. Consideration of these factors may be useful in developing tailored post-treatment imaging surveillance plans.”
Janie M. Lee, MD, of Seattle Cancer Care Alliance, is the corresponding author of the Journal of the National Cancer Institute article.
The study was supported by the National Cancer Institute and Breast Cancer Surveillance Consortium.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
