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Mortality after Metastatic Breast Cancer: Co-morbidity as a Mediator of Age on Survival, and Delays in Treatment for Breast Cancer Metastasis

Jung, Su Yon (2011) Mortality after Metastatic Breast Cancer: Co-morbidity as a Mediator of Age on Survival, and Delays in Treatment for Breast Cancer Metastasis. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Patients with breast cancer metastases have very poor survival. Delays in the initiation of breast cancer treatment may adversely affect survival. Comorbid illness is more common in older women. Comorbid illness may explain effects of age on metastatic breast cancer survival outcomes. Comorbid illness may affect treatment delay.The purpose of the present study was to 1) identify factors related to survival following metastatic breast cancer diagnosis, 2) assess the impact of delay in treatment on survival while controlling for immortal time bias, and 3) evaluate the role of comorbidity as a mediator of survival disparity between younger (≤ 51 years) and older (> 51 years) patients.A total of 557 patients with the initial breast cancer metastasis diagnosis have been followed up between January 1, 1999 and June 30, 2008. Prognostic factors and outcomes of these patients were analyzed using log-rank test and Cox regression model, demonstrating that hypertension, ER/PR, HER2 status, number of metastatic sites, and BMI at metastatic breast cancer diagnosis were the most relevant prognostic factors for survival. Backward stepwise selection of covariates was conducted among 553 patients and showed that treatment delays of > 12 weeks had a marginal impact on poor survival (HR 1.76, 95% CI 0.99-3.13). Moreover, the interval of 12-24 weeks, compared to the interval of 4-12 week was a prognostic factor for survival from first treatment (HR 2.39, 95% CI 1.19-4.77). To assess comorbidity variable as a mediator of age-survival relationship among 553 patients, we applied two approaches: 1) Baron Kenny approach, and 2) alternative assessment to compute the percentage change in the HRs. Hypertension was related to survival (HR 1.45, 95% CI 1.12-1.89) and hypertension augmented Charlson comorbidity score (hCCS) explained survival disparity between young and old patients by 44% compared to 40 % of hypertension and 14% of the Charlson comorbidity score (CCS). Looking for opportunities to improve public health, the present study identifies modifiable factors associated with variable outcomes after diagnosis of metastatic breast cancer.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Jung, Su
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairWeissfeld, Joel Ljwepid@pitt.eduJWEPID
Committee MemberLinkov,
Committee MemberRosenzweig, Margaretmros@pitt.eduMROS
Committee MemberSereika, Susan Mssereika@pitt.eduSSEREIKA
Date: 31 January 2011
Date Type: Completion
Defense Date: 9 December 2010
Approval Date: 31 January 2011
Submission Date: 28 November 2010
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Institution: University of Pittsburgh
Schools and Programs: School of Public Health > Epidemiology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: advanced breast cancer; comorbidity; hypertension; mediation; prognostic factors; treatment delay
Other ID:, etd-11282010-172324
Date Deposited: 10 Nov 2011 20:06
Last Modified: 15 Nov 2016 13:52


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