Localization of Point A in Cervical Cancer

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00319462
Recruitment Status : Unknown
Verified April 2006 by Mackay Memorial Hospital.
Recruitment status was:  Recruiting
First Posted : April 27, 2006
Last Update Posted : April 19, 2007
Information provided by:
Mackay Memorial Hospital

April 27, 2006
April 27, 2006
April 19, 2007
November 2006
Not Provided
Distance difference between anatomiacal and hypothetical point A
Same as current
Complete list of historical versions of study NCT00319462 on Archive Site
Difference from prescribed dose between anatomiacal and hypothetical point A
Same as current
Not Provided
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Localization of Point A in Cervical Cancer
Localization of Anatomic Point A in Cervical Cancer Patients
Point A, the major critical point for dose specification of intracavitary brachytherapy, is defined as the crossing of uterine artery and ureter in treatment of cervical cancer. However, the currently advocated systems use hypothetical point A (HPA) to estimate the dosimetry of brachytherapy. This study is to localize anatomic point A (APA) of cervical cancer patients for reference of radiotherapy. We will use laparoscopic clipping technique to localize APA for cervical cancer patients during pelvic and paraaortic lymph node sampling. When these patients are receiving brachytherapy, orthogonal radiographs will be obtained after insertion of tandem and colpostats by using Henschke afterloading applicators.
Radiation therapy (RT), with a relevant integration of external beam radiotherapy (EBRT) and intracavitary brachytherapy (ICBT), is an important part in the treatment of cervical cancer. Even though concurrent chemoradiation therapy (CCRT) improves the control of locoregional recurrence and distant metastasis for locally advanced disease, the role of RT remains important and essential. ICBT is an essential component of RT and has been used to deliver a high localized dose to the primary cervical lesion and adjacent parametria with an attempt to minimize dose to nearby normal tissues. The conventional point-based dose prescription systems have been applied for decades. Incorporation of modern imaging techniques, namely computerized tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) to ICBT, enable radiation oncologists to individualize treatment volumes but yet, not applicable for routine practice. Point A, since defined by Tod and Meredith in 1938 and revised in 1953, has been widely accepted as a sacrosanct reference point for dose prescription of ICBT. Point A was defined as a point 2 cm above the cervical os and 2 cm apart from os on the line perpendicular to uterine axis. It is a hypothetical point representing the crossover of the ureter and uterine artery, located in the paracervical triangle, and is considered as a critical point for radiation tolerance. This definition of point A provides an easy way to prescribe dose in ICBT and integrate with EBRT. However, its dosimetry according to orthogonal radiographs would depend solely on the applicator geometry but not the individual tumor volume or location. The International Commission on Radiation Units and Measurements (ICRU) report 38 proposed a set of guidelines for uniform reporting. Reporting of the dimensions of reference volumes still depends on the geometry of applied applicator and remains difficult for reporting of ICBT. Thus, point A is still used as a reference point for dose prescription and for correlating the treatment outcome in clinical trials. CCRT has been considered as a standard of care for locally advanced cervical cancer. To further dissect the patient population, which may have a benefit of less morbidity from CCRT, but not radical surgery plus subsequent RT, the sampling of pelvic and paraaortic lymph nodes prior to decision of intended surgery has been utilized by performing laparoscopy or laparotomy for stages IB and IIA. Moreover, this sampling procedure can also provide a pathological proof and delineation of lymph nodes at risk for an important reference of RT field design. During sampling procedures, we observed that the point crossing over the ureter and uterine artery could be visualized and marked by using hemoclips. Therefore, the anatomic position of point A could be visualized on the orthogonal films after closure of abdominal wound. In this study, we attempt to compare the location of and the radiation doses to anatomic point A (APA) and hypothetical point A (HPA) during fractionated ICBT.
Not Applicable
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Cervical Cancer
Device: hemoclip
Not Provided

*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Unknown status
Same as current
April 2007
Not Provided

Inclusion Criteria:

  • Female,
  • Carvical cancer proven by pathology,
  • Indicated for lymph node sampling

Exclusion Criteria:

  • Patient refuse lymph node sampling,
  • History of allergy to metal materials
Sexes Eligible for Study: Female
30 Years to 75 Years   (Adult, Older Adult)
Contact information is only displayed when the study is recruiting subjects
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Mackay Memorial Hospital
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Principal Investigator: Yu-Jen Chen, MD,PhD Mackay Memorial Hospital
Mackay Memorial Hospital
April 2006

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP