Survival Gaps in Lobular Breast Cancer Among Racial Groups

Breast Cancer: Breast CancerA new study has shed light on significant racial disparities in the presentation and survival outcomes of women diagnosed with invasive lobular carcinoma (ILC). The research presented at the 2024 ASCO Annual Meeting, which utilized data from the SEER database spanning 1998-2019, highlights the differences in clinical characteristics and survival rates among women of different racial backgrounds, also comparing these trends with those observed in invasive ductal carcinoma (IDC) and mixed invasive ductal lobular carcinoma (IDLC) (Abstract 1596). The study aimed to characterize the differences in presentation and survival among women of varying races diagnosed with ILC and identify predictors of survival. Researchers performed a population-based retrospective cohort study collecting demographic and clinical data, including race, age, marital status, income, tumor grade, size, laterality, clinical stage, receptor status, type of surgery, chemotherapy, radiation, and breast cancer-specific survival (BCSS). The statistical analysis involved Chi-square tests, one-way ANOVA, and Cox-proportional hazard models with significance set at P<0.05. Key Findings The study included 38,769 women diagnosed with ILC: 32,857 White, 2,398 Black, 2,352 Asian, and 1,162 of other races. The results revealed distinct disparities in disease presentation and treatment across racial groups: Black Women: Presented with higher-grade tumors, more advanced clinical stages, and higher rates of ER+ disease and N2-3 stage. They also had lower rates of undergoing unilateral/bilateral mastectomy and were more likely to forgo surgery (7.13%) compared to White (4.25%) and Asian (4.04%) women. The 5-year BCSS for Black women was 91.5 percent, the lowest among the racial groups studied. Asian Women: Generally younger, with higher rates of ER-/PR- ILC, and received more chemotherapy. Their 5-year BCSS was 93.7 percent. White Women: Presented with more favorable disease characteristics and had a 5-year BCSS of 94.2 percent. Women of Other Races: Had the highest 5-year BCSS at 95.7 percent. Predictors of Survival Several predictors of worse survival were identified: Black Race: Associated with a higher hazard ratio (HR) for mortality (HR: 1.32, P<.0001). ER-/PR- Status: Significantly worse survival (HR: 2.18, P<.0001). ER+/PR- Status: Also linked to poorer outcomes (HR: 1.52, P<.0001). Lack of Surgery: Strong predictor of worse survival (HR: 4.19, P<.0001). Radiotherapy: Correlated with improved survival (HR: 0.82, P<.0001). Chemotherapy: Did not significantly affect survival (HR: 1.1, P=0.0504). Insights in Breast Cancer Subtypes The study also compared these trends across IDC and IDLC: Black Women: Consistently presented with higher-grade tumors, advanced stages, and higher rates of ER+ disease across all subtypes with the lowest 5-year BCSS rates. Asian Women: Showed a higher incidence of ER-/PR- ILC compared to IDC. Predictors of Worse Survival: Negative hormone receptor status and Black race were consistent predictors across all subtypes, while radiation therapy was associated with better survival outcomes. To learn more, Oncology Times reached out to David W. Lim, MDCM, MEd, PhD, FRCSC, Medical Director of the Henrietta Banting Breast Centre and Breast Surgical Oncologist in the Department of Surgery at the Women's College Hospital in Toronto and Assistant Professor of the Division of General Surgery at the University of Toronto. Oncology Times: In the context of this study, how do the patterns of hormone receptor status (ER/PR) vary between different racial groups with lobular breast cancer and what is the impact on survival? Lim: “In all races, the majority of lobular breast cancers were ER-positive and PR-positive (around 75%). Interestingly, there were slightly higher rates of ER+/PR- lobular breast cancers in Black (15.2%) and Asian women (15.5%) compared with White women (14%), suggesting these ethnicities may have more luminal B tumors. We identified more ER-/PR- lobular breast cancers in Asian women (4.4%) compared with White (2.3%) and Black (2.9%) women. “Despite these findings, in Asian women, only ER+/PR- ILC had worse survival than ER+/PR+ ILC (HR: 1.46, P=0.3). In Black women, both ER+/PR- (HR: 1.4, P=0.038) and ER-/PR- (HR: 2.4, P< 0.01) ILC had worse survival than ER+/PR+ ILC. In White women, compared with ER+/PR+ ILC, those with ER+/PR- (HR: 1.56, P<.01), ER-/PR+ (HR: 1.46, P=0.04), and ER-/PR- (HR: 2.3, P=0.02) ILC had worse survival.” Oncology Times: What are the implications of the study's findings for screening and treatment considerations in diverse racial populations with invasive lobular breast cancer? Lim: “While we traditionally consider ILC as a subtype more seen in older, postmenopausal women, which appears to be the case for White women, there are relatively more young Black and Asian women with ILC compared with White women. Black women tend to have higher-grade and more advanced-stage disease, signifying an opportunity for earlier screening to detect cancers at an early stage. It was interesting to see that Asian women had more ER-/PR- ILC, suggesting different biology. At the same time, Black women had worse survival across all subtypes, not just ILC, which likely reflect downstream effects of the social determinants of health.” Dibash Kumar Das is a contributing writer. Most Young Breast Cancer Survivors Can Have Successful Pregnancies Most younger breast cancer patients can conceive and have a live birth after receiving treatment for their cancer, according to a new study presented at the 2024 ASCO Annual Meeting. Learn more at https://tinyurl.com/mrx7bvua.

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