Date of Graduation

2015

Document Type

Dissertation

Degree Type

PhD

College

School of Pharmacy

Department

Pharmaceutical Sciences

Committee Chair

Usha Sambamoorthi

Committee Co-Chair

Suresh Madhavan

Committee Member

Malcolm D Mattes

Committee Member

Xiaoyun Pan

Committee Member

Wenhui Wei

Abstract

Prostate Cancer is the most commonly observed non-skin cancer among the elderly men aged 65 years and older in the United States. Nearly one third of elderly men diagnosed with incident prostate cancer have pre-existing chronic conditions. Therefore, among elderly men with prostate cancer, management for cancer and chronic conditions should be optimized to improve healthcare outcomes. Previous literature majorly focused on the risk and management of cancer in the presence of number of conditions, although, it is known that more than 70% of chronic conditions among men diagnosed with prostate cancer were either cardio-metabolic, respiratory or mental health conditions. Lack of evidence persists regarding the impact of common types of chronic conditions and their conditions among elderly men with prostate cancer and vice-versa. The current study is an attempt to shrink the knowledge gap to provide actionable strategies to better management of chronic conditions and prostate cancer among elderly men. The three specific aims of the study were to: (1) examine the associations between the types of pre-existing chronic conditions and cancer stage at diagnosis, initial cancer treatment and clinical outcomes after initial cancer treatment; 2) examine the relationship between metformin use and cancer stage at diagnosis, and the initial cancer-treatment; 3) analyze the impact of cancer diagnosis on the risk of non-cancer hospitalizations and evaluate whether the impact of cancer diagnosis on the risk of non-cancer hospitalizations vary by the types of pre-existing chronic conditions among fee-for-service elderly Medicare beneficiaries with incident prostate cancer. The study used a retrospective cohort design, using multiple years (2002-2010) of the cancer registry data from the Surveillance, Epidemiology and End Results (SEER) program linked with the Medicare administrative claims data and the Area Health Resource Files (AHRF). In the first aim, among elderly men with incident prostate cancer (N = 103,820), the cardio-vascular conditions were the most common chronic condition. 1 in 10 elderly men had advanced prostate cancer at diagnosis. Elderly men without cardio-metabolic, respiratory or mental health conditions were more likely to be diagnosed with advanced prostate cancer as compared to those with all the three types of chronic conditions. 3 in 4 elderly men with localized prostate cancer received either radical prostatectomy (RP), radiation therapy (RT) or hormone therapy during the first six-month after cancer diagnosis. As compared to all three types of chronic conditions, those with single types of chronic conditions were less likely to develop bowel, and urinary dysfunctions. In the second aim, the use of metformin was associated with a reduction in the risk of advanced prostate cancer among elderly men diagnosed with prostate cancer and pre-existing diabetes (N=2, 652). In the third study, elderly men diagnosed with prostate cancer had an increase in the risk of non-cancer hospitalizations during the post-cancer period as compared to the pre-cancer period in both unadjusted and adjusted analyses. The highest rates of non-cancer hospitalizations were observed during first four months after the diagnosis of prostate cancer. To summarize, our study confirms that elderly men with incident prostate cancer and multiple types of pre-existing chronic conditions would pose a different degree of risk for the development of advanced prostate cancer. Although the management of chronic conditions such diabetes with metformin may reduce the risk of advanced prostate cancer among elderly men. An overuse of RT/RP in men with different types of chronic conditions and an increase in the non-cancer hospitalizations in the initial period after diagnosis of prostate cancer suggest the scope of optimum use of RT and RP and improvement in the care of chronic conditions.

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