Recommendations by Canadian urologists and radiation oncologists for the treatment of clinically localized prostate cancer.

OBJECTIVE: Previous work has shown that urologists and radiation oncologists prefer the treatment that they themselves deliver when treating clinically localized prostate cancer. Our objective was to determine whether Canadian radiation oncologists and urologists have similar biases in favour of the treatments that they themselves deliver for localized prostate cancer. METHODS: We developed a survey to poll the beliefs that Canadian radiation oncologists and urologists held toward prostate specific antigen (PSA) screening, survival benefits of treatment, recommendations for treatment of prostate cancer and the likelihood of side effects with each therapy. RESULTS: Urologists were more likely to recommend routine PSA screening for men up to age 70 (p < 0.001), while radiation oncologists were more likely to recommend PSA screening for men over age 80 (p < 0.04). More urologists felt that there was "definitely" a survival advantage with radical prostatectomy (RP) (60% v. 21%, p < 0.001). More radiation oncologists recommend external beam radiation therapy (EBRT) (p < 0.01) or brachytherapy (p < 0.03) to treat low-risk prostate cancer. More urologists than radiation oncologists recommend RP for intermediate-risk patients (98% v. 70%, p < 0.001). CONCLUSION: Most Canadian urologists and radiation oncologists recommend routine PSA screening for men aged 50 to 70. A significant preference was detected among both urologists and radiation oncologists for the treatment that they themselves deliver. While both urologists and radiation oncologists recommend prostatectomy for the treatment of low-risk localized prostate cancer, urologists are significantly less likely to recommend EBRT. Conversely, when patients present with intermediate-risk prostate cancer, radiation oncologists were significantly less likely than urologists to recommend a prostatectomy.

Experimental validation of the Eclipse AAA algorithm.

The present study evaluates the performance of a newly released photon-beam dose calculation algorithm that is incorporated into an established treatment planning system (TPS). We compared the analytical anisotropic algorithm (AAA) factory-commissioned with "golden beam data" for Varian linear accelerators with measurements performed at two institutions using 6-MV and 15-MV beams. The TG-53 evaluation regions and criteria were used to evaluate profiles measured in a water phantom for a wide variety of clinically relevant beam geometries. The total scatter factor (TSF) for each of these geometries was also measured and compared against the results from the AAA. At one institute, TLD measurements were performed at several points in the neck and thoracic regions of a Rando phantom; at the other institution, ion chamber measurements were performed in a CIRS inhomogeneous phantom. The phantoms were both imaged using computed tomography (CT), and the dose was calculated using the AAA at corresponding detector locations. Evaluation of measured relative dose profiles revealed that 97%, 99%, 97%, and 100% of points at one institute and 96%, 88%, 89%, and 100% of points at the other institution passed TG-53 evaluation criteria in the outer beam, penumbra, inner beam, and buildup regions respectively. Poorer results in the inner beam regions at one institute are attributed to the mismatch of the measured profiles at shallow depths with the "golden beam data." For validation of monitor unit (MU) calculations, the mean difference between measured and calculated TSFs was less than 0.5%; test cases involving physical wedges had, in general, differences of more than 1%. The mean difference between point measurements performed in inhomogeneous phantoms and Eclipse was 2.1% (5.3% maximum) and all differences were within TG-53 guidelines of 7%. By intent, the methods and evaluation techniques were similar to those in a previous investigation involving another convolution-superposition photon-beam dose calculation algorithm in another TPS, so that the current work permitted an independent comparison between the two algorithms for which results have been provided.

Implications of cancer staging uncertainties in radiation therapy decisions.

INTRODUCTION: Radiation therapy (RT) for cancer is a critical medical procedure that occurs in a complex environment involving numerous health professionals, hardware, software, and equipment. Uncertainties and potential incidents can lead to inappropriate administration of radiation to patients, with sometimes catastrophic consequences such as premature death or appreciably impaired quality of life. The authors evaluate the impact of incorrectly staging (i.e., estimation of extent of cancer) breast cancer patients and resulting inappropriate treatment decisions. METHODS: The authors employ analytic and simulation methods in an influence-diagram framework to estimate the probability of incorrect staging and treatment decisions. As inputs, they use a combination of literature information on the accuracy and precision of pathology and tests as well as expert judgment. Sensitivity and value-of-information analyses are conducted to identify important uncertainties. RESULTS AND CONCLUSIONS: The authors find a small but nontrivial probability that breast cancer patients will be incorrectly staged and thus may be subjected to inappropriate treatment. Results are sensitive to a number of variables, and some routinely used tests for metastasis have very limited information value. This work has implications for the methods used in cancer staging, and the methods are generalizable for quantitative risk assessment of treatment errors.