Absolute volume of the rectum and AUC from rectal DVH between 25Gy and 50Gy predict acute gastrointestinal toxicity with IG-IMRT in prostate cancer.

BACKGROUND: To determine whether dose/volume specific endpoints (DVSE) or Area under the rectal DVH curve (rAUC) better predict acute gastrointestinal (GI) toxicity in prostate cancer patients treated with IMRT in the era of daily image guidance (IG-IMRT). METHODS: A set of DVSE was recorded from V25 to V75 (increments of 5Gy) (both in % and in cc) for 180 men. The rAUC was calculated for doses ranging between 25Gy and 50Gy (rAUC25-50). Univariate and multivariate logistic regressions were performed to determine the relationship between DVSE or rAUC25-50 and the appearance of any acute GI toxicity. RESULTS: The rates of acute grade 1 (G1), G2 and G3 GI toxicities were 53.3 %, 10.6 % and 1.1 %, respectively. No G4+ toxicity was observed. Rectal V25 to V75 expressed in % were not predictive of G ≥ 1 GI toxicity (p ≥ 0.12) whereas rectal V25 to V50 expressed in cc did correlate with GI toxicity G ≥ 1 (p ≤ 0.04). rAUC25-50 expressed in cc. Gy correlated significantly with the occurrence of any acute GI toxicity G ≥ 1 (p = 0.027). CONCLUSIONS: The absolute volume of the rectum between 25Gy and 50Gy and rAUC25-50 could significantly predict any acute rectal toxicity in prostate cancer patients treated with daily IG-IMRT.

IMRT credentialing for prospective trials using institutional virtual phantoms: results of a joint European Organization for the Research and Treatment of Cancer and Radiological Physics Center project.

BACKGROUND AND PURPOSE: Intensity-modulated radiotherapy (IMRT) credentialing for a EORTC study was performed using an anthropomorphic head phantom from the Radiological Physics Center (RPC; RPC(PH)). Institutions were retrospectively requested to irradiate their institutional phantom (INST(PH)) using the same treatment plan in the framework of a Virtual Phantom Project (VPP) for IMRT credentialing. MATERIALS AND METHODS: CT data set of the institutional phantom and measured 2D dose matrices were requested from centers and sent to a dedicated secure EORTC uploader. Data from the RPC(PH) and INST(PH) were thereafter centrally analyzed and inter-compared by the QA team using commercially available software (RIT; ver.5.2; Colorado Springs, USA). RESULTS: Eighteen institutions participated to the VPP. The measurements of 6 (33%) institutions could not be analyzed centrally. All other centers passed both the VPP and the RPC ±7%/4 mm credentialing criteria. At the 5%/5 mm gamma criteria (90% of pixels passing), 11(92%) as compared to 12 (100%) centers pass the credentialing process with RPC(PH) and INST(PH) (p = 0.29), respectively. The corresponding pass rate for the 3%/3 mm gamma criteria (90% of pixels passing) was 2 (17%) and 9 (75%; p = 0.01), respectively. CONCLUSIONS: IMRT dosimetry gamma evaluations in a single plane for a H&N prospective trial using the INST(PH) measurements showed agreement at the gamma index criteria of ±5%/5 mm (90% of pixels passing) for a small number of VPP measurements. Using more stringent, criteria, the RPC(PH) and INST(PH) comparison showed disagreement. More data is warranted and urgently required within the framework of prospective studies.

Clinical impact of margin reduction on late toxicity and short-term biochemical control for patients treated with daily on-line image guided IMRT for prostate cancer.

To evaluate the impact of PTV reduction when delivering image-guided IMRT (IG-IMRT) for patients with prostate cancer. Between 2001 and 2007, 165 men were treated with daily IG-IMRT using a 3D ultrasound-based system. Median dose prescribed to the prostate was 78 Gy [74 Gy-78 Gy]. Patients were stratified regarding the CTV to the PTV margin: group A (n=87)=5mm or group B (n=78)=10mm. Late toxicity was scored using the CTC v3.0 scale. Biochemical progression-free survival (bPFS) was calculated using the Phoenix definition. Grade 2 genitourinary toxicity was 7.0% for group A and 6.6% for group B (p=1.00). Grade 2 gastrointestinal toxicity was 1.2% and 2.6% (p=0.38). With a median follow-up of 38.3 months [5.25-87.3], bPFS at 3 years was 92.5% [82.4%-96.9%] in group A and 94.3% [85.5%-97.8%] in group B (p=0.84). IG-IMRT yielded very low rates of late toxicity. Margin had impact neither on short-term bPFS nor late toxicity.

Intensity-modulated radiation therapy in head and neck cancer: prescribed dose, clinical challenges and results.

PURPOSE: To analyse clinical and dosimetric characteristics with regard to clinical constraints in head and neck cancer patients treated with intensity-modulated radiotherapy (IMRT). MATERIALS AND METHODS: Between August 2001 and July 2005, 75 patients with non-metastatic head and neck cancers were treated with IMRT with curative intent. Dose-volume histograms (DVH) drawn up from inverse dosimetry were analysed and compared to the prescription according to the clinical presentation of the disease. RESULTS: For bilateral irradiation, the mean doses delivered to the contralateral and ipsilateral parotid glands were, respectively, 28.1 and 26.3Gy. Dose constraints to the submandibular glands were only respected for the contralateral gland during unilateral irradiation. For tumors located in paranasal sinuses, the maximal dose to the contralateral and ipsilateral optic nerves remained significantly lower than the constraint doses while the constraints for the anterior part of the eyes could not be respected. CONCLUSIONS: Significant differences were observed concerning respect of the constraints applied to the parotid or to the submandibular glands for medial tumors. The respect of constraints for the organs at risk critically depends on the location and size of the primary tumor and on the definition of the CTV. The clinical impact has to be further evaluated.

Clinical assessment of the use of the Sonarray system for daily prostate localization.

The Sonarray ultrasound system is a non-invasive technique allowing real-time prostate localization. Since 2003, it has been used in our department before intensity modulated radiation therapy for prostate cancer. We reported both setup errors and organ motion detected by Sonarray system and the accuracy of this ultrasound imaging dedicated to radiotherapy.

Ultimate results of radiation therapy for T1-T2 mycosis fungoides (including reirradiation).

PURPOSE: We report on our experience in the treatment of T1 and T2 mycosis fungoides (MF) with total skin electron beam therapy (TSEBT), with respect to relapse-free rate, overall survival rate, and management of recurrence. METHODS AND MATERIALS: Between 1975 and 2001, 141 patients with MF were referred to the radiotherapy department for treatment by TSEBT. A total of 57 patients were staged as having T1 or T2 disease (24 T1 and 33 T2 patients). A total of 25 received topical therapy before irradiation. Treatment was delivered through a 6-MeV linear accelerator to a mean total dose of 30 Gy, 2 Gy/day, 4 days/week, for 4 weeks. Close follow-up was initiated without adjuvant therapy. Median age was 61 years (range, 19-84), and median follow-up was 114 months (range, 14-300). RESULTS: Three months after completion of TSEBT, the overall response rate was 94.7%. A complete response was achieved in 87.5% of T1 and 84.8% of T2 patients. Thirty-one patients (54.4%) experienced a skin failure (8 with T1 and 23 with T2 disease) within 1 year. Eighteen patients of 31 received a reirradiation as salvage therapy (6 localized treatment with segmental fields of electron beam irradiation and 12-second TSEB delivering 24 Gy in 12 fractions). Two were treated by topical steroids, and 11 received combination therapy with PUVA (2/10), topical (10/10) or systemic (4/10) chemotherapy, or interferon (7/10). After a second course of TSEBT (4 T1 and 10 T2 patients), the 5-year freedom from relapse rate was 70% vs. 39% in patients having received other modalities. For the whole group, 5-year DFS was 50%. The 5/10/15-year OS were 90%/65%/42%, respectively. In univariate analysis, T1 (p = 0.03), CR after first TSEBT (p = 0.04), and age younger than 60 (p < 0.001) were significant prognostic factor for OS. In multivariate analysis, age younger than 60 years was statistically associated with improved OS (p = 0.001); T stage and completion of CR remained under threshold of significance (p = 0.059 and p = 0.063, respectively). During the mean 86-month period of follow-up from relapse, a second recurrence was observed in 29% of patients. CONCLUSIONS: TSEBT is highly effective in early-stage MF without adjuvant therapy. Management of relapses with local radiotherapy or second TSEBT is feasible, time-saving, and cost-effective.