RTOG GU Radiation oncology specialists reach consensus on pelvic lymph node volumes for high-risk prostate cancer

Abstract

Purpose: Radiation therapy to the pelvic lymph nodes in high-risk prostate cancer is required on several Radiation Therapy Oncology Group (RTOG) clinical trials. Based on a prior lymph node contouring project, we have shown significant disagreement in the definition of pelvic lymph node volumes among genitourinary radiation oncology specialists involved in developing and executing current RTOG trials.

Materials and methods: A consensus meeting was held on October 3, 2007, to reach agreement on pelvic lymph node volumes. Data were presented to address the lymph node drainage of the prostate. Extensive discussion ensued to develop clinical target volume (CTV) pelvic lymph node consensus.

Results: Consensus was obtained resulting in computed tomography image-based pelvic lymph node CTVs. Based on this consensus, the pelvic lymph node volumes to be irradiated include: distal common iliac, presacral lymph nodes (S(1)-S(3)), external iliac lymph nodes, internal iliac lymph nodes, and obturator lymph nodes. Lymph node CTVs include the vessels (artery and vein) and a 7-mm radial margin being careful to "carve out" bowel, bladder, bone, and muscle. Volumes begin at the L5/S1 interspace and end at the superior aspect of the pubic bone. Consensus on dose-volume histogram constraints for OARs was also attained.

Conclusions: Consensus on pelvic lymph node CTVs for radiation therapy to address high-risk prostate cancer was attained and is available as web-based computed tomography images as well as a descriptive format through the RTOG. This will allow for uniformity in evaluating the benefit and risk of such treatment.

Conflict of interest statement

Conflict of Interest: None

Figures

Figure 1. AP/ Lat Simulation Films

Example whole pelvis simulation films for RTOG studies 85-31, 86-10, and 92-02

Figure 2

Representative pelvic lymph node CTV contours from consensus CT: 2a Common Iliac and Presacral CTV lymph node volumes (L5/S1) 2b External, Internal and Presacral CTV lymph node volumes (S1–S3) 2c External and Internal Iliac CTV lymph node volumes (below S3) 2d End of External Iliac CTV lymph node volumes (at top of femoral head – boney landmark for the inguinal ligament) 2e Obturator CTV lymph node volumes (above the top of the pubic symphysis)

Figure 2

Representative pelvic lymph node CTV contours from consensus CT: 2a Common Iliac and Presacral CTV lymph node volumes (L5/S1) 2b External, Internal and Presacral CTV lymph node volumes (S1–S3) 2c External and Internal Iliac CTV lymph node volumes (below S3) 2d End of External Iliac CTV lymph node volumes (at top of femoral head – boney landmark for the inguinal ligament) 2e Obturator CTV lymph node volumes (above the top of the pubic symphysis)

Figure 2

Representative pelvic lymph node CTV contours from consensus CT: 2a Common Iliac and Presacral CTV lymph node volumes (L5/S1) 2b External, Internal and Presacral CTV lymph node volumes (S1–S3) 2c External and Internal Iliac CTV lymph node volumes (below S3) 2d End of External Iliac CTV lymph node volumes (at top of femoral head – boney landmark for the inguinal ligament) 2e Obturator CTV lymph node volumes (above the top of the pubic symphysis)

Figure 2

Representative pelvic lymph node CTV contours from consensus CT: 2a Common Iliac and Presacral CTV lymph node volumes (L5/S1) 2b External, Internal and Presacral CTV lymph node volumes (S1–S3) 2c External and Internal Iliac CTV lymph node volumes (below S3) 2d End of External Iliac CTV lymph node volumes (at top of femoral head – boney landmark for the inguinal ligament) 2e Obturator CTV lymph node volumes (above the top of the pubic symphysis)

Figure 2

Representative pelvic lymph node CTV contours from consensus CT: 2a Common Iliac and Presacral CTV lymph node volumes (L5/S1) 2b External, Internal and Presacral CTV lymph node volumes (S1–S3) 2c External and Internal Iliac CTV lymph node volumes (below S3) 2d End of External Iliac CTV lymph node volumes (at top of femoral head – boney landmark for the inguinal ligament) 2e Obturator CTV lymph node volumes (above the top of the pubic symphysis)

Figure 3

Dose Volume Histogram constraints for Organs At Risk (OARs)