Multimorbidity and cancer treatment among the older patients in the United States - research article

Q: How is multimorbidity defined in the study?

Multimorbidity is defined as having cancer plus two or more comorbidities.

Q: What data and population were used?

The retrospective cohort used SEER-Medicare linked data to identify 692,159 individuals over 65 diagnosed with female breast, colorectal, lung, or prostate cancer from 1992–2011.

Q: What did the results show about treatment receipt?

Across cancers, the proportion receiving treatment declined over time and with increasing age, number of comorbidities, and advanced cancer stage. Patients with multimorbidity were less likely to receive cancer treatment.

Q: What conclusions were drawn about racial disparities and multimorbidity?

The findings suggest multimorbidity prevalence among older patients with cancer increased and negatively affected cancer treatment. Racial disparities may exist and appear more pronounced among patients without multimorbidity.

Sep 22, 2026

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Cancer incidence co-occurs increasingly with comorbidities, and older racial/ethnic minority patients experience a higher burden of additional diseases than non-Hispanic White patients. This study evaluates how multimorbidity relates to cancer treatment decisions within 6 months after diagnosis among older U.S. adults across four common cancer types. Using SEER-Medicare retrospective cohort data and modified Poisson models, the analysis examines both time trends and racial/ethnic variation in treatment receipt.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages15

Reading Time38 min

AccessFree to download

Introduction

Methods

Results

Conclusions

OPEN ACCESS Citation: Pham TT, Connor AE, Rositch AF (2026) Multimorbidity and cancer treatment among the older patients in the United States. PLoS One 21(1): e0338721. [https://doi](https://doi). org/10.1371/journal.pone.0338721 Editor: Sophie Pilleron, Luxembourg Institute of Health, LUXEMBOURG Received: June 23, 2025 Accepted: November 26, 2025 Published: January 7, 2026 Copyright: © 2026 Pham et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data availability statement: This study was a retrospective cohort of older patients with cancer in the United States in the Surveillance, Epidemiology, and End Results (SEER) -Medicare linkage database. The data could be obtained via SEER-Medicare and subjected to approval from National Cancer Institute; Information Management Services (IMS), Inc.; RESEARCH ARTICLE Multimorbidity and cancer treatment among the older patients in the United States Tung Thanh Pham1,2,3*, Avonne E. Connor4,5, Anne F. Rositch4,6 1 College of Health Sciences, VinUniversity, Hanoi, Vietnam, 2 Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America, 3 Research Advancement Consortium in Health (REACH), Hanoi, Vietnam, 4 Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America, 5 Department of Oncology, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, Maryland, United States of America, 6 Health Outcomes and Real World Evidence, Hologic, Inc, Marlborough, Massachusetts, United States of America * [tung.pt@vinuni.edu.vn](tung.pt@vinuni.edu.vn) Abstract Introduction The number of individuals who are diagnosed with cancer and other comorbidities continues to increase, and the average number of comorbidities among racial/ethnic minority patients is higher than non-Hispanic (N. H.)-white patients. Therefore, we explored the association between race/ethnicity, comorbidities, and cancer treatment among older Americans diagnosed with the four most common cancer types. Methods In this retrospective cohort study, SEER-Medicare linked data were used to identify 692,159 individuals over 65 years old diagnosed with female breast, colorectal, lung, or prostate cancer from 1992–2011. Multimorbidity was defined as having cancer plus two or more comorbidities. Modified Poisson regression models were used to assess the association between comorbidities and race/ethnicity on cancer treatment within 6 months of diagnosis. Results For all cancers, the percentage of patients receiving treatment declined over time and with increasing age, number of comorbidities, and advanced cancer stage. Variability in receipt of treatment by race/ethnicity was observed: 76% for NH-White, 75% for Hispanic, and 68% for NH-Black patients. Concurrently, multimorbidity was increasing over time for all patients. Adjusting for other covariates, patients with multimorbidity were less likely to receive cancer treatment (RR = 0.987–0.947, all p-value<0 .001) . Moreover, NH-Black (RR = 0.955–0.865, all p-value<0 .001) and PLOS One | [https://doi.org/10.1371/journal.pone.0338721](https://doi.org/10.1371/journal.pone.0338721) January 7, 2026 1 / 15 and the Surveillance, Epidemiology, and End Results (SEER) Program tumor registries. For data access inquiries, please contact: SEERMedicare Information Management Services, Inc. 3901 Calverton Blvd, Suite 200 Calverton, MD 20705 E-mail: SEERMedicare@imsweb. ” com . Funding: The author(s) received no specific funding for this work. Competing interests: NO authors have competing interests. Hispanic (RR = 0.987–0.951, all p-value<0 .001) patients without multimorbidity were less likely to be treated compared to NH-White patients

FAQs

How is multimorbidity defined in the study?

Multimorbidity is defined as having cancer plus two or more comorbidities.

What data and population were used?

The retrospective cohort used SEER-Medicare linked data to identify 692,159 individuals over 65 diagnosed with female breast, colorectal, lung, or prostate cancer from 1992–2011.

What did the results show about treatment receipt?

Across cancers, the proportion receiving treatment declined over time and with increasing age, number of comorbidities, and advanced cancer stage. Patients with multimorbidity were less likely to receive cancer treatment.

What conclusions were drawn about racial disparities and multimorbidity?

The findings suggest multimorbidity prevalence among older patients with cancer increased and negatively affected cancer treatment. Racial disparities may exist and appear more pronounced among patients without multimorbidity.

Sep 22, 2026

Upload by Logic