Elective Clinical Target Volumes for Conformal Therapy in Anorectal Cancer: A Radiation Therapy Oncology Group Consensus Panel Contouring Atlas

Abstract

Purpose To develop a Radiation Therapy Oncology Group (RTOG) atlas of the elective clinical target volume (CTV) definitions to be used for planning pelvic intensity-modulated radiotherapy (IMRT) for anal and rectal cancers. Methods and Materials The Gastrointestinal Committee of the RTOG established a task group (the nine physician co-authors) to develop this atlas. They responded to a questionnaire concerning three elective CTVs (CTVA: internal iliac, pre-sacral and peri-rectal nodal regions for both anal and rectal case planning; CTVB: external iliac nodal region for anal case planning and for selected rectal cases; CTVC: inguinal nodal region for anal case planning and for select rectal cases), and to outline these areas on individual computed tomography images. The imaging files were shared via the Advanced Technology Consortium. A program developed by one of the co-authors (IEN) utilized binomial maximum-likelihood estimates to generate a 95% group consensus contour. The computer-estimated consensus contours were then reviewed by the group and modified to provide a final contouring consensus atlas. Results The panel achieved consensus CTV definitions to be used as guidelines for the adjuvant therapy of rectal cancer and definitive therapy for anal cancer. The most important difference from similar atlases for gynecologic or genitourinary cancer is mesorectal coverage. Detailed target volume contouring guidelines and images are discussed. Conclusion This report serves as a template for the definition of the elective CTVs to be used in IMRT planning for anal and rectal cancers, as part of prospective RTOG trials.

Intensity-Modulated Radiation Therapy with Simultaneous Integrated Boost Combined with Concurrent Chemotherapy for the Treatment of Anal Cancer Patients: 4-Year Results of a Consecutive Case Series

“…In general, lymphatic areas were contoured as a 10 mm isotropic expansion around regional vessels, with a subsequent modification to exclude bones and muscles. A subsequent 10 mm isotropic margin was added to generate the consequential planning target volume (PTV), accounting for organ motion and set up errors (14,15). This margin remained the same throughout the years in this cohort of patients for homogeneity, even if different strategies of image-guidance were employed during those years (weekly portal imaging for early and daily KvCT/MvCT for late patients).…”

“…For inverse planning, target volumes objectives were driven to obtain at least 95% of the prescribed dose to 95% of the PTV, 110% of prescription dose to ≤ 10% of the PTV and ≤ 2% of PTV receiving < 95% of prescribed dose. OARs dose constraints were adapted from Kachnic et al (14). Three different treatment modalities were available for Combined Chemoradiation for Anal Cancer Patients  patients: step and shoot (S&S) IMRT, volumetric arc-therapy (VMAT), and helical tomotherapy (HT).…”

Dosimetric Comparison of Volumetric Modulated Arc Therapy (VMAT), 5F Intensity Modulated Radiotherapy (IMRT) and 3D Conformal Radiotherapy (3DCRT) in Rectal Carcinoma Receiving Neoadjuvant Chemoradiotherapy

“…50 and 62 and Myerson, R.J. et al [7]. The gross tumour volume (GTV) was delineated further according to the information obtained from the diagnostic CT and MRI, including the rectal primary tumor and invaded lymph nodes.…”

Bone marrow tolerance during postoperative chemotherapy in colorectal carcinomas

“…Rectal cancer patients underwent radiation treatment consistent with Radiation Therapy Oncology Group treatment guidelines for rectal cancers (12,15,16). Patients were treated with either intensity-modulated radiation therapy (IMRT) (n=20, 57.1%) or 3D-conformal radiation therapy (3D-CRT) (n=15, 42.8%) to a median dose of 50.4 Gy (range: 48.6-54 Gy) in 1.8 Gy/day fractions.…”