Relationship Between Breast Density, Breast Cancer Subtypes, and Prognosis

• Published in: Clinical breast cancer 2022-08, Vol.22 (6), p.560-566
• Main Authors: Yamada, Daisuke, Ohde, Sachiko, Kajiura, Yuka, Yagishita, Kazuyo, Nozaki, Fumi, Suzuki, Koyu, Kanomata, Naoki, Yamauchi, Hideko, Tsunoda, Hiroko
• Format: Article
• Language: English
• Subjects: Breast cancer; Breast density; Dense breast; Mammography; Survival rate
• ISSN: 1526-8209; 1938-0666
• DOI: 10.1016/j.clbc.2022.04.005

•The link between breast density, breast cancer subtype, and prognosis is unclear.•We examined breast cancer subtype and breast composition in Japanese women.•No relationship was detected between the cancer subtypes and breast composition.•Treatment decision should continue to be made based on cancer subtype. In the United States, Europe, and Asia, a consensus has been reached that there is a higher risk of breast cancer in high density breasts. However, there are some contrary reports that suggest the absence of an association between breast composition and breast cancer subtype; thus, there is conflicting evidence. The purpose of this study was to investigate trends in the incidence of breast cancer subtypes according to breast composition and analyze the survival rates in Japanese women. Between 2007 and 2008, 1258 Japanese patients with invasive breast cancer who underwent mammography and obtained a pathological diagnosis in our institution were included in the study. We compared cancer subtypes with breast composition types (dense and non-dense breast), and classified them based on initial mammography findings. Information on 5- and 10-year survival rates was collected by chart review for patients with dense and nondense breasts. Statistical analysis was performed using the Pearson's chi-square test for breast composition and cancer subtype. The effect of breast composition on mortality was examined using a multivariate Cox proportional hazards model, and adjusted hazard ratios were calculated. No significant difference was found between breast cancer subtype and breast composition (P = .08). Five-year (log-rank test, P = .09) and 10-year (log-rank test, P = .31) survival rates were not significantly different between breast composition types. There was no significant association between breast composition and cancer subtypes. There was also no significant difference in the prognosis between patients with and without dense breasts. The relationship between breast density, breast cancer subtype, and prognosis is unclear. We examined the connection between breast cancer subtypes and breast composition in 1258 women with breast cancer who underwent mammography and obtained a pathological diagnosis. There was no association between breast composition and breast cancer subtype. Treatment decision should be based on cancer subtype, not breast density.