International Journal of Radiation Oncology*Biology*Physics
Clinical InvestigationConsensus Guidelines for Delineation of Clinical Target Volume for Intensity-Modulated Pelvic Radiotherapy for the Definitive Treatment of Cervix Cancer
Introduction
Intensity-modulated radiotherapy (IMRT) is being increasingly explored as a means to reduce normal tissue toxicity in cervix cancer with or without treatment intensification (such as extended-field radiotherapy or concomitant boost) 1, 2, 3, 4, 5, 6. Reductions in acute and late toxicities with the use of IMRT have been reported in conjunction with low rates of in-field failures2, 3, 7. Accurate target definition is vitally important to ensure the target is not under-treated and to limit the dose to surrounding normal tissues. There are published guidelines on clinical target volume (CTV) definitions for a number of tumor sites including the postoperative gynecological and prostatectomy setting 8, 9. However, CTV definitions for IMRT for the radical treatment of cervix cancer remain variable within the literature2, 3, 5, 6, 10. The amount of organ motion, tumor regression, and deformation that cervix cancer patients demonstrate is more substantial than in prostate cancer 11, 12, 13, 14, 15, 16, 17, 18. These complex intrapelvic organ dynamics imply greater caution when highly conformal radiotherapy (such as IMRT) is used for this site than for prostate cancer. In order for IMRT to be delivered safely, adequate planning tumor volume (PTV) margins are necessary to account for CTV motion.
The aim of this report is to provide consensus guidelines for defining CTV for the intact cervix in order to achieve safe clinical IMRT practice in preparation for a planned Radiation Therapy Oncology Group (RTOG) Phase 2 clinical trial. These guidelines would supplement currently published consensus guidelines on postoperative IMRT for endometrial and cervix cancer (9).
Section snippets
Methods and Materials
A proposal for a prospective RTOG trial evaluating the role of IMRT in the definitive cervix cancer setting was the impetus behind the development of these guidelines. Representatives from the following groups participated in the Gyn IMRT Consortium: RTOG; National Cancer Institute of Canada; Japan Clinical Oncology Group; and European Society of Therapeutic Radiology and Oncology.
An electronic survey among Consortium members was undertaken prior to the June 2008 RTOG meeting to determine
Results
A total of 16 members from the Consortium were surveyed, with a response rate of 75% (12/16). There was general consensus on the structures to be included in the CTV (such as GTV, cervix, uterus, parametria, vagina, and regional lymph nodes) but less agreement regarding the definition of these structures for the purposes of contouring. All respondents agreed that the lateral boundary of parametria should be at the pelvic sidewall and that the medial boundary of parametria should abut the GTV,
Discussion
Traditional whole-pelvis radiotherapy fields based on bony landmarks encompasses targets within the pelvis with little sparing of OAR. The benefit of these large treatment volumes is that geographical miss is minimized. In the era of more conformal treatment, where target delineation becomes critical, one of the major difficulties with pelvic IMRT for the radical treatment of cervix cancer lies in the definition of the CTV components. While there is general agreement on what constitutes the
Conclusions
This is the first consensus document attempting to clarify target definitions for whole-pelvis IMRT for the intact cervix. It was felt that clear target definition guidelines would be useful in achieving consistency across different treatment centers. This report does not attempt to address issues of minimizing organ motion or adaptation to organ motion or tumor regression. The value of this document lies in providing groundwork for safe practice, building on previously published guidelines for
Acknowledgment
The names of the radiation oncologists who contributed to this work as members of the Gyn IMRT Consortium are listed in the Addendum to this article.
References (34)
- et al.
IMRT dose escalation for positive para-aortic lymph nodes in patients with locally advanced cervical cancer while reducing dose to bone marrow and other organs at risk
Int J Radiat Oncol Biol Phys
(2004) - et al.
Early clinical outcome with concurrent chemotherapy and extended-field, intensity-modulated radiotherapy for cervical cancer
Int J Radiat Oncol Biol Phys
(2007) - et al.
Feasibility of concurrent cisplatin and extended field radiation therapy (EFRT) using intensity-modulated radiotherapy (IMRT) for carcinoma of the cervix
Gynecol Oncol
(2006) - et al.
Dosimetric predictors of acute hematologic toxicity in cervical cancer patients treated with concurrent cisplatin and intensity-modulated pelvic radiotherapy
Int J Radiat Oncol Biol Phys
(2006) - et al.
Intensity-modulated radiation therapy (IMRT) reduces small bowel, rectum, and bladder doses in patients with cervical cancer receiving pelvic and para-aortic irradiation
Int J Radiat Oncol Biol Phys
(2001) - et al.
Conventional, conformal, and intensity-modulated radiation therapy treatment planning of external beam radiotherapy for cervical cancer: The impact of tumor regression
Int J Radiat Oncol Biol Phys
(2006) - et al.
Preliminary outcome and toxicity report of extended-field, intensity-modulated radiation therapy for gynecologic malignancies
Int J Radiat Oncol Biol Phys
(2006) - et al.
Consensus guidelines for delineation of clinical target volume for intensity-modulated pelvic radiotherapy in postoperative treatment of endometrial and cervical cancer
Int J Radiat Oncol Biol Phys
(2008) - et al.
Preliminary analysis of chronic gastrointestinal toxicity in gynecology patients treated with intensity-modulated whole pelvic radiation therapy
Int J Radiat Oncol Biol Phys
(2003) - et al.
Impact of the filling status of the bladder and rectum on their integral dose distribution and the movement of the uterus in the treatment planning of gynaecological cancer
Radiother Oncol
(1999)
Inter- and intrafractional tumor and organ movement in patients with cervical cancer undergoing radiotherapy: A cinematic-MRI point-of-interest study
Int J Radiat Oncol Biol Phys
Interfractional variation in position of the uterus during radical radiotherapy for cervical cancer
Radiother Oncol
Detection of organ movement in cervix cancer patients using a fluoroscopic electronic portal imaging device and radiopaque markers
Int J Radiat Oncol Biol Phys
Rapid involution and mobility of carcinoma of the cervix
Int J Radiat Oncol Biol Phys
Motion and deformation of the target volumes during IMRT for cervical cancer: What margins do we need?
Radiother Oncol
Classification of radical hysterectomy
Lancet Oncol
Association between the mesenchymal compartment of uterovaginal organogenesis and local tumour spread in stage IB-IIB cervical carcinoma: a prospective study
Lancet Onco
Cited by (357)
Less than whole uterus irradiation for patients with locally advanced cervical cancer
2024, Radiotherapy and OncologyOptimizing Online Adaptation Timing in the Treatment of Locally Advanced Cervical Cancer
2024, Practical Radiation OncologyClinical Implementation of “Plan of the Day” Strategy in Definitive Radiation Therapy of Cervical Cancer: Online Adaptation to Address the Challenge of Organ Filling Reproducibility
2024, International Journal of Radiation Oncology Biology PhysicsDose and fractionation regimen for brachytherapy boost in cervical cancer in the US
2024, Gynecologic Oncology
Conflict of interest: none.