Date of Award

January 2023

Document Type


Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Michaela Dinan

Second Advisor

Maryam Lustberg


Aim: We aimed to investigate the association between age at diagnosis and time spent seeking care for Metastatic Breast Cancer (MBC) and to identify the major components of acute and outpatient care contributing towards time lost in seeking cancer treatment i.e., time toxicity. Methods: We conducted a longitudinal retrospective cohort study in MBC patients aged 67 or older who initiated treatment from 2010-2017 using the SEER-Medicare linked database. We calculated the cancer-related encounter days by summing up the patients' healthcare system interactions within one year of initiating cancer treatment for each category. We used a Poisson model with days alive as an offset variable to examine the association between age and encounter days within the first year of treatment adjusting for various factors. We stratified encounter days by treatment type and care category for each age group and performed ANOVA and Tukey post hoc tests to identify significant differences. Results: Among the 2,780 Medicare patients, those aged 80+years at diagnosis had the highest encounter days within the first year of treatment initiation (64.753.1 days), followed by those aged 67-69 years (62.940.8 days) and 70-79 years (61.9 44.3). However, no significant association was found between age at diagnosis and encounter days. More comorbidities were significantly associated with higher encounter days. Radiotherapy, chemotherapy, and HER-2 specific biologic therapy were significantly associated with more encounter days (adjusted RR values: 1.33, 1.20, and 1.10 respectively), while non-HER2 therapy showed a slightly protective effect (adjusted RR: 0.83). Conclusion: To improve care for older patients with MBC, patient-centered and time-efficient models need to be developed that incorporate information on time costs. This requires a better understanding of time toxicity, shared decision-making, and comparative research on patient management strategies.


This thesis is restricted to Yale network users only. It will be made publicly available on 05/22/2026