Impact of age, comorbidity, and polypharmacy on receipt of systemic therapy in advanced cancers: A retrospective population-based study.

Introduction: Cancer incidence, comorbidity, and polypharmacy increase with age, but the interplay between these factors on receipt of systemic therapy (ST) in advanced cancer has rarely been studied.
Materials and Methods: A retrospective cohort study was conducted including patients aged ≥18 years diagnosed from 2004 to 2015 with multiple myeloma (MM) (all stages), lung cancer (stage IV), and stage III-IV non-Hodgkin's lymphoma (NHL), breast, colorectal (CRC), prostate, or ovarian cancer in Manitoba, Canada. Clinical and administrative health data were used to determine demographic and cancer characteristics, treatment history, comorbidity (Charlson Comorbidity Index [CCI] and Resource Utilization Band [RUB]), and polypharmacy (≥6 medications). Multivariable logistic regression was used to evaluate variable associations with receipt of ST and interaction with age.
Results: In total, 17,228 patients were diagnosed with advanced cancer. Ages were distributed as follows: 7% <50 years, 16% 50-59 years, 26% 60-69, 26% 70-79, 24% ≥80 years. ST was administered to 50% of patients. Increased age, polypharmacy, and comorbidity each independently decreased the likelihood of receiving ST. Significant interaction effects were found between age at diagnosis with stage of cancer and cancer type. Differences in probability of ST by cancer stage converged as age increased. In multivariable analysis, adjusting for covariates, patients with MM had the highest odds and lung cancer the lowest odds to receive ST. The impact of comorbidity and polypharmacy did not differ meaningfully with increasing age.
Discussion: Increased age, polypharmacy, and comorbidity were each independently associated with decreased receipt of ST in people with advanced cancers. The impact of comorbidity and polypharmacy did not differ meaningfully with increasing age, while age meaningfully interacted with stage and cancer type.
Competing Interests: Declaration of Competing Interest Rebekah Rittberg reports honorarium for educational content and research grant funding from AstraZeneca. Philip St. John reports speaking fees from McMaster University and Regional Geriatric Program of Eastern Ontario, and consulting fees from University Health Network. David E. Dawe reports advisory board attendance for Merck Canada, Jazz Pharmaceuticals, Novartis, Pfizer, and AstraZeneca, honoraria for education content from Boehringer-Ingelheim, Bristol Myers Squibb, and Roche, and grants from AstraZeneca Canada. Kathleen Decker, Pascal Lambert, Jen Bravo, Donna Turner, and Piotr Czaykowski report no conflicts of interest.
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