Comparison of Conventional-Dose vs High-Dose Conformal Radiation Therapy in Clinically Localized Adenocarcinoma of the Prostate

Abstract

Context Clinically localized prostate cancer is very prevalent among US men, but recurrence after treatment with conventional radiation therapy is common. Objective To evaluate the hypothesis that increasing the radiation dose delivered to men with clinically localized prostate cancer improves disease outcome. Design, Setting, and Patients Randomized controlled trial of 393 patients with stage T1b through T2b prostate cancer and prostate-specific antigen (PSA) levels less than 15 ng/mL randomized between January 1996 and December 1999 and treated at 2 US academic institutions. Median age was 67 years and median PSA level was 6.3 ng/mL. Median follow-up was 5.5 (range, 1.2-8.2) years. Intervention Patients were randomized to receive external beam radiation to a total dose of either 70.2 Gy (conventional dose) or 79.2 Gy (high dose). This was delivered using a combination of conformal photon and proton beams. Main Outcome Measure Increasing PSA level (ie, biochemical failure) 5 years after treatment. Results The proportions of men free from biochemical failure at 5 years were 61.4% (95% confidence interval, 54.6%-68.3%) for conventional-dose and 80.4% (95% confidence interval, 74.7%-86.1%) for high-dose therapy (PϽ.001), a 49% reduction in the risk of failure. The advantage to high-dose therapy was observed in both the low-risk and the higher-risk subgroups (risk reduction, 51% [PϽ.001] and 44% [P=.03], respectively). There has been no significant difference in overall survival rates between the treatment groups. Only 1% of patients receiving conventional-dose and 2% receiving high-dose radiation experienced acute urinary or rectal morbidity of Radiation Therapy Oncology Group (RTOG) grade 3 or greater. So far, only 2% and 1%, respectively, have experienced late morbidity of RTOG grade 3 or greater. Conclusions Men with clinically localized prostate cancer have a lower risk of biochemical failure if they receive high-dose rather than conventional-dose conformal radiation. This advantage was achieved without any associated increase in RTOG grade 3 acute or late urinary or rectal morbidity.

Assessment of setup uncertainties for various tumor sites when using daily CBCT for more than 2200 VMAT treatments

“…Intensity‐modulated radiation therapy (IMRT) can deliver highly conformal radiation to the target, whilst sparing adjacent critical organs and other normal tissues 1 , 2 , 3 , 4 , 5 , 6 , 7 . Increasingly sharp dose gradients generated by IMRT require more accurate target localization and precise patient positioning because small setup errors can compromise target coverage and increase the dose to organs at risk 8 , 9 , 10 , 11 , 12 .…”

Evaluation of techniques for slice sensitivity profile measurement and analysis

“…In order for an axial slice to be reconstructed, the helical dataset needs to be interpolated to create a full set of projection data within the plane of reconstruction. The use of projection data from outside the reconstructed volume leads to a reduction in axial resolution 1 , 2 , 3 , 4 , 5 The slice sensitivity profile (SSP) allows the measurement of the axial resolution of helical CT systems.…”

“…During the infancy of Helical CT, much research was done to determine what factors of the CT scanner affected the axial resolution 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 . The size of the focal spot, the width of the detectors, and the penumbra due to the focal spot are all factors that impact the SSP that are not controllable by the user 1 , 2 , 3 , 4 .…”

“…The size of the focal spot, the width of the detectors, and the penumbra due to the focal spot are all factors that impact the SSP that are not controllable by the user 1 , 2 , 3 , 4 . There are robust data showing that adjustable factors affecting the sinogram data, such as pitch, detector configuration, and various methods of interpolating the sinogram data, namely full scan interpolation and half scan interpolation, impact the blurring of the system in the axial direction 6 , 8 , 12 , 13 .…”

Quantification of the margin required for treating intraprostatic lesions

“…One disease site in radiation oncology that has seen an increase in MRI is the prostate, where the high‐risk intraprostatic lesion (IPL) can be identified 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 . Since dose escalation can improve cure rates, delivering an escalated dose to the IPL while treating the remainder of the prostate to the normal prescription dose can reduce toxicity while increasing tumor control 12 , 13 , 14 . Technologies like intensity‐modulated radiation therapy (IMRT) allow for delivery of different dose levels using a simultaneous integrated intraprostatic boost (SIIB), but at the same time generate steep dose gradients requiring exact knowledge of the location of the prostate and IPL.…”