Five-Year Overall Survival of Interval Breast Cancers is Better than Non- Interval Cancers from Korean Breast Cancer Registry

Abstract

Objective: Interval breast cancer (IC) is a limitation of breast cancer screening. We investigated data from a<br />large scaled breast cancer dataset of patients with breast cancer who underwent breast cancer screening in order to<br />recapitulate the overall survival (OS) of patients with ICs compared to those with non-ICs. Methods: A total of 27,141<br />patients in the Korean breast cancer registry with breast cancer who had ever participated in biannual national breast<br />cancer screening programs between 2009 and 2013 were enrolled. We compared the social, pregnancy-associated, and<br />pathologic characteristics between the IC and non-IC groups and identified the significant prognostic factors for OS.<br />Results: The proportion of ICs was 1.3% (370/27,141) in this study population. ICs were correlated with age 45-55<br />years at diagnosis, higher levels of education, early menopause (provinces (Kangwon, Kyungnam, Jeju, and Dae-jeon), and family history of breast cancer. Low-to-intermediate nuclear<br />grade, early stage (stage 0-I), and low Ki-67 level were also correlated with IC proportion. Non-ICs were associated<br />with an increased risk of five-year mortality (hazard ratio [HR] 7.4; 95% confidence interval [CI]:1.85-29.66; p = 0.005)<br />compared to ICs. Lymph node metastasis, residence (Kyung-nam province), low education status, high histologic grade,<br />and asymptomatic cancers increased the HR of five-year OS. Conclusion: ICs occurred unequally in specific province<br />and relatively high-educated women in Korea. They were also diagnosed with early-stage breast cancer with a favorable<br />recurrence risk, and their outcome was better than those of patients with other breast cancers in breast cancer screening.