Patient-assessed late toxicity rates and principal component analysis after image-guided radiation therapy for prostate cancer.

Abstract

PURPOSE:

The aims of this study were to determine the incidence of patient-assessed late toxicity after high-dose, image-guided radiation therapy in a cohort of men with prostate cancer; and to correlate toxicity with conventional dosimetric parameters and rectal and bladder dose-volume histograms (DVH) reduced using principal component analysis.

METHODS AND MATERIALS:

Toxicity questionnaires were sent to 690 men treated for localized prostate cancer to 75.6 Gy or 79.8 Gy using three-dimensional conformal radiation therapy (3DCRT) or intensity-modulated radiation therapy (IMRT) between 1997 and 2003 at the Princess Margaret Hospital. Toxicity was graded according to the modified Radiation Therapy Oncology Group (RTOG)-late effects normal tissue (LENT) scoring system. Late rectal and bladder toxicity scores were dichotomized as < Grade 2 and > or = Grade 2, and correlated with dosimetric parameters and with the first three principal components of rectal and bladder DVHs.

RESULTS:

In all, 63% of the patients completed the questionnaire. At a median follow-up of 37 months, the incidence of late rectal toxicity RTOG Grades 1, 2, and 3 was 25.2%, 2.5%, and 0.7% respectively. The incidence of late urinary toxicity RTOG Grade 1, 2, and 3 was 16.5%, 8.8%, and 0.9% respectively. Maintenance of erectile function sufficient for intercourse was reported in 68%. No dosimetric parameter analyzed, including principal component analysis reduction of DVHs, correlated with late toxicity.

CONCLUSIONS:

Postal questionnaire was effective for collection of patient-assessed late toxicity data. The incidence of late toxicity was low, with a lack of correlation to dosimetric parameters. We attribute this to the use of conformal techniques and daily image guidance.

• Authors: Marketa Skala, Tara Rosewall, Laura Dawson, Lorella Divanbeigi, Gina Lockwood, Christopher Thomas, Juanita Crook, Peter Chung, Padraig Warde, Charles Catton
• Journal: International journal of radiation oncology, biology, physics (Int J Radiat Oncol Biol Phys) Vol. 68 Issue 3 Pg. 690-8 (Jul 01 2007) ISSN: 0360-3016 [Print] United States
• PMID: 17379434 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Diagnostic Imaging (statistics & numerical data)
• Humans
• Incidence
• Male
• Ontario (epidemiology)
• Principal Component Analysis
• Prostatic Neoplasms (diagnosis, epidemiology, radiotherapy)
• Radiation Injuries (epidemiology)
• Radiotherapy Dosage
• Radiotherapy, Computer-Assisted (statistics & numerical data)
• Radiotherapy, Conformal (statistics & numerical data)
• Rectal Diseases (epidemiology)
• Retrospective Studies
• Risk Assessment (methods)
• Risk Factors
• Surveys and Questionnaires
• Urinary Bladder Diseases (epidemiology)