Author

Ann Raldow

Date of Award

January 2011

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

James B. Yu

Second Advisor

Roy H. Decker

Subject Area(s)

Health sciences, Oncology

Abstract

Purposes:

This thesis represents the composition of three different research topics within prostate cancer radiation therapy. Part I examines the delivery of curative therapy (CTx) in older men with localized prostate cancer across strata of potential clinical benefit and examines treatment trends over time. Part II is an institutional retrospective review of patients treated to 75.6 Gy to the prostate using intensity modulated radiation therapy (IMRT) without the explicit contouring of the seminal vesicles. Part III is a literature review of adjuvant (ART) and salvage (SRT) radiation therapy to examine the optimal timing of radiation therapy after radical prostatectomy.

Methods:

In Part I, we used the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database to identify 64,192 men ages 67-85 with localized prostate cancer diagnosed from 1996 through 2005. We assessed CTx use, defined as either prostatectomy or radiation, across strata of potential likelihood of clinical benefit. In Part II, patients treated from January 2000 through January 2007 at our institution for clinically localized prostate cancer using IMRT were identified and consecutive patients were selected if they had more than 3 years of follow up and received at least 75.6 Gy. Clinical information was gathered, toxicity was recorded, and biochemical disease-free survival was calculated. In Part III, pub-med was searched using keywords prostate cancer and: radiation therapy; adjuvant radiation therapy; salvage radiation therapy; post-operative radiation therapy

Results:

Part I.. Among patients with the lowest likelihood of clinical benefit (low risk cancer and LE <5 years), those diagnosed in 2004-2005 were more than twice as likely to receive CTx as those diagnosed in 1996-1997 (35.3% vs. 16.0%, respectively). Part II. Two hundred twenty three (223) eligible patients received primary IMRT for prostate cancer and the median follow up was 4.4 years. 5-year BDFS for poor, intermediate, and favorable prognostic group patients was 59.0% [95% Confidence Interval (95% CI) 41.8-72.7%], 83.4% [95% CI 72.4-90.4%], and 92.1% [95% CI 77.4-97.4%], respectively. Acute and late genitourinary and gastrointestinal Grade-3 toxicities were rare and there were no Grade-4 toxicities.Part III Although there are multiple randomized trials suggesting that early intervention with ART can improve biochemical disease-free, metastasis-free and overall survival in patients at high risk of recurrence, a similar level of evidence does not exist for the use of SRT.

Conclusions:

Part I. Curative therapy for prostate cancer may be increasingly utilized among patients with the lowest likelihood of clinical benefit. Part II. Dose escalation using IMRT to treat the prostate without explicit contouring of the seminal vesicles is safe and effective. Part III. We anticipate the results from randomized clinical trials to answer further questions regarding the comparison of ART to SRT following biochemical relapse.

Comments

This is an Open Access Thesis.

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