Dose escalation with IMRT was associated with improved cancer control in intermediate- and high-risk patients in comparison with 3D-CRT, without compromising toxicity.

No abstract

Sufficient dose coverage of target volumes was not achieved for all patients. Reducing of safety margin is not acceptable. Initial rectal and bladder volumes cannot be considered representative for subsequent treatment.

Rectum and bladder are the crucial organs at risk for curative radiation therapy of localized prostate cancer. We analyzed the incidence, profile and time course of late rectal radiation toxicity. A total of 320 patients with T1-3 prostate cancer were treated with three-dimensional conformal radiation therapy (3D-CRT). The prescription dose was 70 Gy for T1 and T2 patients (n ¼ 230) and 74 Gy for patients with locally advanced T3 tumors (n ¼ 90). Late rectal toxicity was graded according to the Fox Chase modification of the Radiation Therapy Oncology Group (RTOG) and Late Effects Normal Tissue Task Force (LENT) criteria. The median follow-up time was 6.2 years (range 0.2-10.7 years). At 5 years, the risk for the development of grade 2 and 3 rectal toxicities was 15.6 and 7.0%, respectively. All new cases of grade 2 and 3 rectal toxicities were observed within 5 years after treatment. Prevalence of grade 2 and 3 rectal symptoms showed fluctuation with maximum at 1.5 years and the minor peak at 4.5 years. Toxicity profile changed significantly over time. The proportion of rectal bleeding within grade 2 and 3 toxicity decreased from 85% at 1.5 years to 46% at 4.5 years. Conversely, the proportion of fecal incontinence among grade 2 and 3 rectal symptoms gradually increased (0% at 1.5 years vs 27% at 4.5 years). Late rectal radiation toxicity represents a dynamic process. Rectal bleeding decreases and fecal incontinence increases over time.

The purpose of this study was to compare two different styles of prostate IGRT: bony landmark (BL) setup vs. fiducial markers (FM) setup. Twenty‐nine prostate patients were treated with daily BL setup and 30 patients with daily FM setup. Delivered dose distribution was reconstructed on cone‐beam CT (CBCT) acquired once a week immediately after the alignment. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed 1 cm safety margin. Alternative plans assuming smaller 7 mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with initial ones. While the margin reduction in case of BL setup makes the prostate coverage significantly worse (p=0.0003, McNemar's test), in case of FM setup with the reduced 7 mm margin, the prostate coverage is even better compared to BL setup with 10 mm margin (p=0.049, Fisher's exact test). Moreover, partial volumes of organs at risk irradiated with a specific dose can be significantly lowered (p<0.0001, unpaired t‐test). Reducing of safety margin is not acceptable in case of BL setup, while the margin can be lowered from 10 mm to 7 mm in case of FM setup.PACS numbers: 87.55.dk, 87.55.km, 87.55.tm