Doctor of Philosophy
Norman V. Carroll
Renal cell carcinoma (RCC) is the most common type of kidney cancer. Patients diagnosed with metastatic RCC (mRCC) have shorter overall survival compared to those diagnosed at earlier stages. Several targeted therapies, which cost from $7,000 - $16,000 per month have been approved since 2005 to treat mRCC. In addition, there is a growing interest in the use of cytoreductive nephrectomy (CN) with targeted therapies among mRCC patients. However, little is known regarding the economic burden of RCC and role of CN and prescribing patterns of targeted therapies among older mRCC patients.
1) To assess the economic burden of RCC among older adults in the targeted therapy era 2) To compare the overall survival (OS) and total healthcare cost (THC) among older mRCC patients receiving CN and targeted therapy versus patients receiving targeted therapy alone 3) To describe prescribing patterns of targeted therapies and associated OS and THC among older mRCC patients.
This dissertation was conducted using the Surveillance Epidemiology and End Results (SEER) - Medicare linked data. For the first objective, the study included a prevalent cohort of RCC patients from 2013, diagnosed during 2005 - 2013 and continuously enrolled in Medicare. RCC patients were matched to non-cancer beneficiaries using propensity score matching. Generalized linear models estimated the incremental healthcare costs. Incremental total healthcare cost (THC) was multiplied by the estimated number of RCC patients on Medicare to calculate the total economic burden of RCC. For the second objective, we included patients diagnosed with mRCC between 2007-2014 and compared overall survival (OS), and THC between patients who received CN + targeted therapy and targeted therapy alone. A propensity score based inverse probability of treatment weighting (IPTW) method was used to balance the two treatment groups. A Cox proportional hazard model assessed the risk for death and a GLM compared healthcare costs between the groups. For the third objective, patients with mRCC were defined as patients who were diagnosed at stage-IV or at earlier stages but were currently using targeted therapies. Further, we restricted our sample to patients who initiated targeted therapy. We described the frequencies of the most common first and second line targeted therapies. We also described OS and THC per month for clear-cell and non-clear cell mRCC for each therapy and line of therapy.
The first study included 10,392 each of RCC and control patients. The average THC associated with RCC was $7,419. The average THC was $4,584 for patients diagnosed at stage-I, $4,727 for stage-II, $9,331 for stage-III, and $31,637 for stage-IV. The annual economic burden of RCC on Medicare was estimated to be $1.5 billion. The second study included 471 mRCC patients that received CN + targeted therapy or targeted therapy alone. The median OS from the adjusted survival curves was significantly higher (p
The economic burden of RCC varied substantially between early stage and metastatic patients. Among mRCC patients, use of CN among targeted therapy users was associated with a higher median OS and similar monthly THC over a lifetime. Sunitinib and everolimus were the most common first and second line targeted therapies among mRCC patients. The descriptive analysis suggested that OS and THC were similar across types of targeted therapy sequences.
© Hrishikesh P. Kale
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