Adalsteinn Gunnlaugsson

Dose-volume relationships between enteritis and irradiated bowel volumes during 5-fluorouracil and oxaliplatin based chemoradiotherapy in locally advanced rectal cancer.

Purpose. Radiation enteritis is the main acute side-effect during pelvic irradiation. The aim of this study was to quantify the dose-volume relationship between irradiated bowel volumes and acute enteritis during combined chemoradiotherapy for rectal cancer. Material and methods. Twenty-eight patients with locally advanced rectal cancer received chemoradiotherapy. The radiation therapy was given with a traditional multi-field technique to a total dose of 50 Gy, with concurrent 5-Fluorouracil (5-FU) and oxaliplatin (OXA) based chemotherapy. All patients underwent three-dimensional CT-based treatment planning. Individual loops of small and large bowel as well as a volume defined as “whole abdomen” were systematically contoured on each CT slice, and dose-volume histograms were generated. Diarrhea during treatment was scored retrospectively according to the NCI Common Toxicity Criteria scale. Results. There was a strong correlation between the occurrence of grade 2+diarrhea and irradiated small bowel volume, most notably at doses >15 Gy. Neither irradiated large bowel volume, nor irradiated “whole abdomen” volume correlated significantly with diarrhea. Clinical or treatment related factors such as age, gender, hypertension, previous surgery, enterostomy, or dose fractionation (1.8 vs. 2.0 Gy/fraction) did not correlate with grade 2+diarrhea. Discussion. This study indicates a strong dose-volume relationship between small bowel volume and radiation enteritis during 5-FU-OXA-based chemoradiotherapy. These findings support the application of maneuvers to minimize small bowel irradiation, such as using a “belly board” or the use of IMRT technique aiming at keeping the small bowel volume receiving more than 15 Gy under 150 cc.

Technical Note: MRI only prostate radiotherapy planning using the statistical decomposition algorithm.

PURPOSE In order to enable a magnetic resonance imaging (MRI) only workflow in radiotherapy treatment planning, methods are required for generating Hounsfield unit (HU) maps (i.e., synthetic computed tomography, sCT) for dose calculations, directly from MRI. The Statistical Decomposition Algorithm (SDA) is a method for automatically generating sCT images from a single MR image volume, based on automatic tissue classification in combination with a model trained using a multimodal template material. This study compares dose calculations between sCT generated by the SDA and conventional CT in the male pelvic region. METHODS The study comprised ten prostate cancer patients, for whom a 3D T2 weighted MRI and a conventional planning CT were acquired. For each patient, sCT images were generated from the acquired MRI using the SDA. In order to decouple the effect of variations in patient geometry between imaging modalities from the effect of uncertainties in the SDA, the conventional CT was nonrigidly registered to the MRI to assure that their geometries were well aligned. For each patient, a volumetric modulated arc therapy plan was created for the registered CT (rCT) and recalculated for both the sCT and the conventional CT. The results were evaluated using several methods, including mean average error (MAE), a set of dose-volume histogram parameters, and a restrictive gamma criterion (2% local dose/1 mm). RESULTS The MAE within the body contour was 36.5 ± 4.1 (1 s.d.) HU between sCT and rCT. Average mean absorbed dose difference to target was 0.0% ± 0.2% (1 s.d.) between sCT and rCT, whereas it was -0.3% ± 0.3% (1 s.d.) between CT and rCT. The average gamma pass rate was 99.9% for sCT vs rCT, whereas it was 90.3% for CT vs rCT. CONCLUSIONS The SDA enables a highly accurate MRI only workflow in prostate radiotherapy planning. The dosimetric uncertainties originating from the SDA appear negligible and are notably lower than the uncertainties introduced by variations in patient geometry between imaging sessions.

Multicentre phase II trial of capecitabine and oxaliplatin in combination with radiotherapy for unresectable colorectal cancer: The CORGI-L study

AIMS This study assessed radiotherapy combined with capecitabine and oxaliplatin in patients with primary, inextirpable colorectal adenocarcinoma. PATIENTS AND METHODS Forty-nine patients entered the trial. Two cycles of XELOX (capecitabine 1000 mg/m(2) bid d1-14+oxaliplatin 130 mg/m(2) d1, q3w) were followed by radiotherapy (50.4 Gy), combined with capecitabine 825 mg/m(2) bid every radiotherapy day and oxaliplatin 60 mg/m(2) once weekly. The primary end-point was objective response. RESULTS Forty-seven patients were evaluable. Twenty-nine (62% [95% CI: 46-75%]) achieved complete or partial response. Thirty-eight (81%) went through surgery of whom 37 (97%) had an R0 resection and five (13%) had a pathological complete response. Seventy-eight percent were alive and estimated local progression rate was 11% at 2 years. The most common grade 3+ toxicity during chemoradiotherapy was diarrhoea (24%). CONCLUSIONS XELOX-RT was feasible and showed promising efficacy when treating patients with primary inextirpable colorectal cancer, establishing high local control rate.

Phase I study of cetuximab in combination with 5-fluorouracil, mitomycin C and radiotherapy in patients with locally advanced anal cancer

BACKGROUND 5-fluorouracil (5FU) and mitomycin C (MMC)-based chemoradiotherapy (CRT) is standard treatment for anal squamous cell carcinoma. In this phase I study cetuximab was added and the primary aim was to determine the maximum tolerated dose (MTD) of 5FU and MMC in this combination. METHODS AND MATERIALS Patients with locally advanced anal cancer, T2 (≥4 cm)-4N0-3M0, received weekly standard doses of cetuximab starting 1 week before CRT. Intensity modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB) was given to 57.5/54.0/48.6 Gy in 27 fractions to primary tumour/lymph node metastases/adjuvant lymph node regions. 5FU/MMC was given concomitantly on RT weeks 1 and 5 according to a predefined dose escalation schedule. RESULTS Thirteen patients were enrolled. Two patients discontinued cetuximab due to hypersensitivity reaction. The median age was 65 years (range 46-70), nine were females, and 85% had stage IIIB disease. Dose-limiting toxicity events (diarrheoa, febrile neutropenia and thrombocytopenia) occurred in 3 of 11 patients. The most common grade 3-4 side-effects were radiation dermatitis (63%), haematologic toxicity (54%), and diarrheoa (36%). No treatment-related deaths occurred. Three months following completion of treatment, ten patients (91%) had a local complete remission (CR), but two patients had developed liver metastases, yielding a total CR rate of 73%. CONCLUSION The MTDs were determined as 5FU 800 mg/m(2) on RT days 1-4 and 29-32 and MMC 8 mg/m(2) on days 1 and 29 when combined with IMRT/VMAT with SIB and cetuximab in locally advanced anal cancer.

Multicentre phase I-II trial of capecitabine and oxaliplatin in combination with radiotherapy for unresectable pancreatic and biliary tract cancer: The CORGI-U study.

BACKGROUND AND PURPOSE In this multicentre phase I-II trial we evaluated the feasibility and efficacy of capecitabine and oxaliplatin followed by the combination of these two drugs with radiotherapy in patients with locally advanced pancreatic or biliary tract cancer. MATERIAL AND METHODS Thirty-nine patients with inextirpable adenocarcinoma of the pancreas, gallbladder or extrahepatic bile ducts were included. Two cycles of XELOX (capecitabine 1000 mg/m(2) bid d1-14+oxaliplatin 130 mg/m(2) d1, q3w) were followed by XELOX-RT (radiotherapy (50.4 Gy), combined with capecitabine 750-675 mg/m(2) bid every radiotherapy day and oxaliplatin 40-30 mg/m(2) once weekly). Primary end-points were tolerance (phase I) and objective response (phase II). RESULTS The maximum tolerated doses of oxaliplatin and capecitabine to combine with irradiation were 30 mg/m(2) and 675 mg/m(2), respectively. Twenty-one percent (95% CI: 9-38%) of evaluable patients achieved partial response. Five patients went through surgery (three R0 resections). Two-year survival was 28%, and estimated local tumour control rate at 2 years was 72%. The most common grade 3-4 toxicity was nausea and vomiting. CONCLUSIONS XELOX-RT (30 mg/m(2) oxaliplatin/675 mg/m(2) capecitabine in combination with 50.4Gy/28 fractions) was well tolerated and effective for locally advanced pancreatic and biliary tract cancer.

A national approach for automated collection of standardized and population-based radiation therapy data in Sweden.

PURPOSE To develop an infrastructure for structured and automated collection of interoperable radiation therapy (RT) data into a national clinical quality registry. MATERIALS AND METHODS The present study was initiated in 2012 with the participation of seven of the 15 hospital departments delivering RT in Sweden. A national RT nomenclature and a database for structured unified storage of RT data at each site (Medical Information Quality Archive, MIQA) have been developed. Aggregated data from the MIQA databases are sent to a national RT registry located on the same IT platform (INCA) as the national clinical cancer registries. RESULTS The suggested naming convention has to date been integrated into the clinical workflow at 12 of 15 sites, and MIQA is installed at six of these. Involvement of the remaining 3/15 RT departments is ongoing, and they are expected to be part of the infrastructure by 2016. RT data collection from ARIA®, Mosaiq®, Eclipse™, and Oncentra® is supported. Manual curation of RT-structure information is needed for approximately 10% of target volumes, but rarely for normal tissue structures, demonstrating a good compliance to the RT nomenclature. Aggregated dose/volume descriptors are calculated based on the information in MIQA and sent to INCA using a dedicated service (MIQA2INCA). Correct linkage of data for each patient to the clinical cancer registries on the INCA platform is assured by the unique Swedish personal identity number. CONCLUSIONS An infrastructure for structured and automated prospective collection of syntactically interoperable RT data into a national clinical quality registry for RT data is under implementation. Future developments include adapting MIQA to other treatment modalities (e.g. proton therapy and brachytherapy) and finding strategies to harmonize structure delineations. How the RT registry should comply with domain-specific ontologies such as the Radiation Oncology Ontology (ROO) is under discussion.

Change in prostate volume during extreme hypo-fractionation analysed with MRI.

BackgroundHypo-fractionated external beam radiotherapy with narrow CTV-PTV margins is increasingly applied for prostate cancer. This demands a precise target definition and knowledge on target location and extension during treatment. It is unclear how increase in fraction size affects changes in prostate volume during treatment. Our aim was to study prostate volume changes during extreme hypo-fractionation (7 × 6.1 Gy) by using sequential MRIs.MethodsTwenty patients treated with extreme hypo-fractionation were recruited from an on-going prospective randomized phase III trial. An MRI scan was done before start of treatment, at mid treatment and at the end of radiotherapy. The prostate was delineated at each MRI and the volume and maximum extension in left-right, anterior-posterior and cranial-caudal directions were measured.ResultsThere was a significant increase in mean prostate volume (14%) at mid treatment as compared to baseline. The prostate volume remained enlarged (9%) at the end of radiotherapy. Prostate swelling was most pronounced in the anterior-posterior and cranial-caudal directions.ConclusionsExtreme hypo-fractionation induced a significant prostate swelling during treatment that was still present at the time of last treatment fraction. Our results indicate that prostate swelling is an important factor to take into account when applying treatment margins during short extreme hypo-fractionation, and that tight margins should be applied with caution.

The effect on the small bowel of 5-FU and oxaliplatin in combination with radiation using a microcolony survival assay.

BackgroundIn locally advanced rectal cancer, 5-Fluorouracil (5-FU)-based chemoradiation is the standard treatment. The main acute toxicity of this treatment is enteritis. Due to its potential radiosensitizing properties, oxaliplatin has recently been incorporated in many clinical chemoradiation protocols. The aim of this study was to investigate to what extent 5-FU and oxaliplatin influence the radiation (RT) induced small bowel mucosal damage when given in conjunction with single or split dose RT.MethodsImmune competent balb-c mice were treated with varying doses of 5-FU, oxaliplatin (given intraperitoneally) and total body RT, alone or in different combinations in a series of experiments. The small bowel damage was studied by a microcolony survival assay. The treatment effect was evaluated using the inverse of the slope (D0) of the exponential part of the dose-response curve.ResultsIn two separate experiments the dose-response relations were determined for single doses of RT alone, yielding D0 values of 2.79 Gy (95% CI: 2.65 - 2.95) and 2.98 Gy (2.66 - 3.39), for doses in the intervals of 5-17 Gy and 5-10 Gy, respectively. Equitoxic low doses (IC5) of the two drugs in combination with RT caused a decrease in jejunal crypt count with significantly lower D0: 2.30 Gy (2.10 - 2.56) for RT+5-FU and 2.27 Gy (2.08 - 2.49) for RT+oxaliplatin. Adding both drugs to RT did not further decrease D0: 2.28 Gy (1.97 - 2.71) for RT+5-FU+oxaliplatin. A clearly higher crypt survival was noted for split course radiation (3 × 2.5 Gy) compared to a single fraction of 7.5 Gy. The same difference was seen when 5-FU and/or oxaliplatin were added.ConclusionCombining 5-FU or oxaliplatin with RT lead to an increase in mucosal damage as compared to RT alone in our experimental setting. No additional reduction of jejunal crypt counts was noted when both drugs were combined with single dose RT. The higher crypt survival with split dose radiation indicates a substantial recovery between radiation fractions. This mucosal-sparing effect achieved by fractionation was maintained also when chemotherapy was added.

Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

Purpose: The superior soft tissue contrast of magnetic resonance imaging (MRI) compared to computed tomography (CT) has urged the integration of MRI and elimination of CT in radiotherapy treatment (RT) for prostate. An intraprostatic gold fiducial marker (GFM) appears hyperintense on CT. On T2‐weighted (T2w) MRI target delineation images, the GFM appear as a small signal void similar to calcifications and post biopsy fibrosis. It can therefore be difficult to identify the markers without CT. Detectability of GFMs can be improved using additional MR images, which are manually registered to target delineation images. This task requires manual labor, and is associated with interoperator differences and image registration errors. The aim of this work was to develop and evaluate an automatic method for identification of GFMs directly in the target delineation images without the need for image registration. Methods: T2w images, intended for target delineation, and multiecho gradient echo (MEGRE) images intended for GFM identification, were acquired for prostate cancer patients. Signal voids in the target delineation images were identified as GFM candidates. The GFM appeared as round, symmetric, signal void with increasing area for increasing echo time in the MEGRE images. These image features were exploited for automatic identification of GFMs in a MATLAB model using a patient training dataset (n = 20). The model was validated on an independent patient dataset (n = 40). The distances between the identified GFM in the target delineation images and the GFM in CT images were measured. A human observatory study was conducted to validate the use of MEGRE images. Results: The sensitivity, specificity, and accuracy of the automatic method and the observatory study was 84%, 74%, 81% and 98%, 94%, 97%, respectively. The mean absolute difference in the GFM distances for the automatic method and observatory study was 1.28 ± 1.25 mm and 1.14 ± 1.06 mm, respectively. Conclusions: Multiecho gradient echo images were shown to be a feasible and reliable way to perform GFM identification. For clinical practice, visual inspection of the results from the automatic method is needed at the current stage.

Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images – Generalized technique for four different MR scanners

BACKGROUND AND PURPOSE Recent studies have shown that it is possible to conduct entire radiotherapy treatment planning (RTP) workflow using only MR images. This study aims to develop a generalized intensity-based method to generate synthetic CT (sCT) images from standard T2-weighted (T2w) MR images of the pelvis. MATERIALS AND METHODS This study developed a generalized dual model HU conversion method to convert standard T2w MR image intensity values to synthetic HU values, separately inside and outside of atlas-segmented bone volume contour. The method was developed and evaluated with 20 and 35 prostate cancer patients, respectively. MR images with scanning sequences in clinical use were acquired with four different MR scanners of three vendors. RESULTS For the generated synthetic CT (sCT) images of the 35 prostate patients, the mean (and maximal) HU differences in soft and bony tissue volumes were 16 ± 6 HUs (34 HUs) and -46 ± 56 HUs (181 HUs), respectively, against the true CT images. The average of the PTV mean dose difference in sCTs compared to those in true CTs was -0.6 ± 0.4% (-1.3%). CONCLUSIONS The study provides a generalized method for sCT creation from standard T2w images of the pelvis. The method produced clinically acceptable dose calculation results for all the included scanners and MR sequences.