In a Korean study reported in JAMA Network Open, Song et al identified risk factors for interval breast cancer vs screen-detected breast cancer and described mortality outcomes for women in the two categories.
Study Details
The retrospective cohort study used data from the Korean National Health Insurance Service Database, including women who participated in a national mammographic breast cancer screening program between January 2009 and December 2012. Interval breast cancer was defined as disease diagnosed within 6 to 24 months after a negative screening result; screen-detected breast cancer was defined as disease diagnosed within 6 months after a positive screening result.
Key Findings
The study included 8,702 women with interval breast cancer and 9,492 with screen-detected breast cancer. Compared with screen-detected disease, the probability of interval breast cancer decreased as BI-RADS mammographic density category increased. Compared with density category 1, the likelihood was significantly decreased for category 2 (adjusted odds ratio [OR] = 0.76), category 3 (adjusted OR = 0.70), and category 4 (adjusted OR = 0.80).
Compared with women with obesity, lower body mass index was significantly associated with a higher likelihood of interval breast cancer among women with overweight (adjusted OR = 1.19), normal weight (adjusted OR = 1.24), and underweight (adjusted OR = 1.36). Postmenopausal status (adjusted OR = 1.21) and ever use of hormone replacement therapy (HRT) after menopause (adjusted OR = 1.40) were significantly associated with interval vs screen-detected breast cancer.
Younger age at breast cancer diagnosis and family history of breast cancer were associated with an increased likelihood of interval breast cancer diagnosed at 6 to 12 months but a decreased likelihood of interval breast cancer diagnosed at 12 to 24 months.
Mean follow-up was 8.4 years for women with interval breast cancer and 9.5 years for those with screen-detected breast cancer. Overall, no significant differences between the interval breast cancer group vs the screen-detected breast cancer group were observed for all-cause mortality, breast cancer–related death, deaths other than those from breast cancer, or deaths other than those from any cancer.
The interval breast cancer group had a significant 1.12-fold higher risk of any cancer-related death. Compared with the screen-detected breast cancer group, patients with interval breast cancer diagnosed within 6 to 12 months after negative screening had a significant 1.18-fold higher risk of death from all causes, 1.19-fold higher risk of breast cancer–related death, and 1.20-fold increased risk of any cancer-related death. No increase in overall or any cause-specific mortality vs screen-detected breast cancer was observed with interval breast cancer diagnosed at 12 to 24 months.
Conclusions
The investigators concluded: “The findings of this cohort study suggest that breast density, obesity, and HRT use were associated with [interval breast cancer] compared with [screen-detected breast cancer]. These findings also suggest that higher supplemental breast ultrasound use among Korean women, especially those with dense breasts, could be attributed to a lower incidence of [interval breast cancer] among women with dense breasts compared with women with [screen-detected breast cancer], due to greater detection. Finally, overall mortality of [interval breast cancer] was comparable with that of [screen-detected breast cancer].”
Boyoung Park, MD, PhD, of the Department of Preventive Medicine, Hanyang University College of Medicine, Seoul, is the corresponding author of the JAMA Network Open article.
Disclosure: The study was supported by the National Research Foundation of Korea and funded by the Korean Ministry of Science and Information and Communication Technology. For full disclosures of the study authors, visit jamanetwork.com.
