What is the clinical evidence from this study?

Study design: Cohort. Population: Breast cancer (n=4412). Intervention: Hispanic/Latino race/ethnicity vs. Non-Hispanic White race/ethnicity. Primary outcome: Second primary malignancy (SPM) (HR 0.64, 95% CI 0.43-0.95).

What question did this study set out to answer?

To evaluate the risk of second primary malignancies across different racial and ethnic groups among breast cancer survivors.

April 5, 2026

Abstract 5221: Racial/ethnic disparities in risk of second primary malignancy among women in the Pathways Study of breast cancer survivors

Key Result

Hispanic/Latino breast cancer survivors had a significantly lower risk of developing a second primary malignancy compared with non-Hispanic White survivors (HR 0.64; 95% CI 0.43-0.95).

Key Points

To evaluate the risk of second primary malignancies across different racial and ethnic groups among breast cancer survivors.
Analyzed risk of second primary malignancy in a cohort of 4,412 breast cancer survivors.
Utilized a Fine-Gray sub distribution hazard model to assess associations with self-identified race/ethnicity.
Adjusted for confounding factors such as age, stage, grade, hormone receptor status, and treatment type.
13.6% of the study participants developed a second primary malignancy after a median follow-up of 14.2 years.
Hispanic/Latino women had a significantly lower risk of developing a second primary malignancy compared to White women (HR=0.64).
Older age at breast cancer diagnosis (60 years and above) was significantly associated with increased risk of second primary malignancies.

Study Design

Type

Cohort (n=4,412)

Multicenter

Structured PICO

Does self-identified race/ethnicity affect the risk of developing a second primary malignancy in women with a history of breast cancer?

Population

4,412 women with newly diagnosed, invasive breast cancer between 2006 and 2013 at Kaiser Permanente Northern California (KPNC)

Intervention

Self-identified race/ethnicity (Hispanic/Latino, non-Hispanic Black, non-Hispanic Asian American/Pacific Islander)

Comparator

Non-Hispanic White women

Outcome

Development of a second primary malignancy (SPM)hard clinical

Hispanic/Latino breast cancer survivors have a significantly lower risk of developing a second primary malignancy compared to White survivors.

Main Result

Effect estimate: HR 0.64 (95% CI 0.43-0.95)

Abstract

Abstract Background: Breast cancer (BC) survivors face a significantly increased risk of developing a second primary malignancy (SPM). While late-effects of cancer treatments contribute to SPM risk, shared behavioral and genetic factors that lead to the initial BC may also affect development of SPM. Previous studies have reported significant racial/ethnic disparities in BC incidence and mortality; however, few have examined disparities on the risk of SPM after BC. The aim of this study was to evaluate SPM risk across racial and ethnic groups of women with BC. Methods: We examined risk of SPM in the Pathways Study, a prospective cohort study of 4,504 women with newly diagnosed, invasive BC between the years 2006 and 2013, at Kaiser Permanente Northern California (KPNC). Associations between self-identified race/ethnicity (categorized as non-Hispanic White White, non-Hispanic Black Black, non-Hispanic Asian American/Pacific Islander AAPI and Hispanic/Latino H/L) and SPM was evaluated using a univariate Fine-Gray sub distribution hazard model. Models were adjusted for age, stage, grade, hormone receptor status and treatment type. Due to small numbers, 92 American Indian/Alaska Native participants were excluded. Follow-up was from date of BC diagnosis to SPM, disenrollment from the KPNC health plan, death, or December 31, 2022, whichever came first. Results: Of the 4,412 BC patients included in the study, 2,950 (66.9%) were White, 351 (8.0%) Black, 599 (13.6%) AAPI and 512 (11.6%) were H/L. Overall, 612 (13.6%) developed a SPM (median follow-up time=14.2 years; range=9.8-17.3). Among 521 patients with known SPM sites, breast (197, 37.8%), reproductive organs (74, 14.2%) and lung (48, 9.2%) were most common sites. In multivariable analyses, we found that compared with White women, H/L had a significantly decreased risk of developing a SPM (Hazard Ratio HR=0.64; 95% Confidence Interval 95%CI=0.43-0.95). Although we also observed lower risk of SPM in AAPI and Black women (HRs of 0.71, 95%CI=0.49-1.02; and 0.79, 95%CI=0.51-1.22, respectively), these associations did not reach statistical significance. Besides race/ethnicity, age at BC diagnosis was also a significant predictor of SPM risk. Older age at diagnosis (60-69 and 70+ years) was associated with significantly increased SPM risk (HR60-69=1.66, 95% CI=1.17-2.34 and HR70+=2.37, 95% CI=1.64-3.41) compared with women diagnosed at 50 years. Conclusion: We observed substantial disparities in SPM risk by race/ethnicity in the KPNC BC survivor’s cohort, with H/L patients experiencing lower risk than Whites, whereas those in the older age group (60+ years) experienced higher risks. Further research to understand drivers of these racial, ethnic and age-related heterogeneity is warranted. Tailored surveillance strategies accounting for these characteristics may help reduce disparities among BC survivors. Citation Format: Pragati Gole Advani, Lia D’Addario, Cecile A. Laurent, Janise M. Roh, Marilyn L. Kwan, Theresa H. Keegan, Isaac J. Ergas, Scarlett L. Gomez, Han Yu, Christine B. Ambrosone, Lawrence H. Kushi. Racial/ethnic disparities in risk of second primary malignancy among women in the Pathways Study of breast cancer survivors abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5221.

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