Variability of clinical target volume delineation for rectal cancer patients planned for neoadjuvant radiotherapy with the aid of the platform Anatom-e.

OBJECTIVE: Delineation of treatment volumes is a major source of uncertainties in radiotherapy (RT). This is also true for rectal cancer patients undergoing neoadjuvant RT, with a potential impact on treatment quality. We investigated the role of the digital platform Anatom-e (Anatom-e Information Sytems Ltd., Houston, Texas) in increasing the compliance to follow a specific treatment protocol in a multicentric setting. MATERIALS AND METHODS: Two clinical cases of locally advanced rectal cancer were chosen. Participants were instructed to follow the 2009 Radiation Therapy Oncology Group consensus atlas and asked to manually segment clinical target volumes (CTVs), for both patient 1 and 2, on day 1 with and without the use of Anatom-e. After one week (day 2), the same radiation oncologist contoured again, with and without Anatom-e, the same CT series. Intraobserver (Intra-OV) and interobserver (Inter-OV) variability were evaluated with the Dice similarity coefficient (DSC), the Hausdorff distance (HD) and mean distance to agreement (MDA). RESULTS: For clinical case 1, no significant difference was found for Intra-OV and Inter-OV. For clinical case 2, no significant difference was found for Intra-OV but a statistically significant difference was found for Inter-OV in DSC when using or not the platform. Mean DCS was 0.65 (SD: ±0.64; range: 0.58-0.79) for day 1 vs reference volume without Anatom-e and 0.72 (SD: ±0.39; range: 0.67-0.77) (p = 0.03) with it. Mean MDA was lower with Anatom-e (3.61; SD: ±1.33; range: 2.85-4.78) than without (4.14; SD: ±2.97; range: 2.18-5.21), with no statistical significance (p = 0.21) The use of Anatom-e decreased the SD from 2.97 to 1.33. Mean HD was lower with Anatom-e (26.06; SD: ±2.05; range: 24.08-32.62), with no statistical significance (p = 0.14) compared to that without (31.39; SD: ±1.31; range: 26.14-48.72). CONCLUSIONS: The use of Anatom-e decreased the Inter-OV in the CTV delineation process for locally advanced rectal cancer with complex disease presentation planned for neoadjuvant RT. This system may be potentially helpful in increasing the compliance to follow shared guidelines and protocols.

Patterns of practice in the radiation therapy management of rectal cancer: survey of the Interregional Group Piedmont, Valle d'Aosta and Liguria of the "Associazione Italiana di Radioterapia Oncologica (AIRO)".

AIMS AND BACKGROUND: To report the survey about the main aspects on the use of radiotherapy for the treatment of rectal cancer in Piedmont and Liguria. METHODS AND STUDY DESIGN: Sixteen centers (11 from Piedmont and 5 from Liguria) received and answered by email a questionnaire data base about clinical and technical aspects of the treatment of rectal cancer. All data were incorporated in a single data base and analyzed. RESULTS: Data regarding 593 patients who received radiotherapy for rectal cancer during the year 2009 were collected and analyzed. Staging consisted in colonoscopy, thoracic and abdominal CT, pelvic MRI and endoscopic ultrasound. PET/CT was employed to complete staging and in the treatment planning in 12/16 centers (75%). Neoadjuvant radiotherapy was employed more frequently than adjuvant radiotherapy (50% vs 36.4%), using typically a total dose of 45 Gy with 1.8 Gy/fraction. Concurrent chemoradiation with 5-fluorouracil or capecitabine was mainly employed in neoadjuvant and adjuvant settings, whereas oxaliplatin alone or in combination with 5-FU or capecitabine and leucovorin was commonly employed as the adjuvant agent. The median interval from neoadjuvant treatment to surgery was 7 weeks after long-course radiotherapy and 8 days after short-course radiotherapy. The pelvic total dose of 45 Gy in the adjuvant setting was the same in all the centers. Doses higher than 45 Gy were employed with a radical intent or in case of positive surgical margins. Hypofractionated regimens (2.5, 3 Gy to a total dose of 35-30 Gy) were used in the palliative setting. No relevant differences were observed in target volume definition and patient setup. Twenty-six patients (4.4%) developed grade 3 acute toxicity. Follow-up was scheduled in a similar way in all the centers. CONCLUSIONS: No relevant differences were found among the centers involved in the survey. The approach can help clinicians to address important clinical questions and to improve consistency and homogeneity of treatments.

Target volume delineation for preoperative radiotherapy of rectal cancer: inter-observer variability and potential impact of FDG-PET/CT imaging.

To analyze the inter-observer variability and the potential impact of (18)F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) imaging for target volume delineation in preoperative radiotherapy of rectal cancer. Gross tumor volume (GTV) and clinical target volume (CTV) in 2 cases of rectal cancer were contoured by 10 radiation oncologists, 5 on CT and 5 on PET/CT images. Resulting volumes were analyzed by coefficient of variation (CV) and concordance index (CI). Mean GTV was 120 cc +/- 20.4 cc in case A and 119 cc +/- 35.7 cc in case B. Mean CTV was 723 cc +/- 147.5 cc in case A and 739 cc +/- 195.6 cc in case B. CV was lower and CI was similar or higher across the observers contouring GTV on PET/CT. CTV variability was less influenced by the use of PET/CT. PET/CT may allow reducing inter-observer variability in GTV delineation.