Optimized coverage of high-risk adjuvant lymph node areas in prostate cancer using a sentinel node-based, intensity-modulated radiation therapy technique.
OBJECTIVE
Irradiation of adjuvant lymph nodes in high-risk prostate cancer was shown to be associated with improved rates of biochemical nonevidence of disease in the Radiation Therapy Oncology Group trial (RTOG 94-13). To account for the highly individual lymphatic drainage pattern we tested an intensity-modulated radiation therapy (IMRT) approach based on the determination of pelvic sentinel lymph nodes (SN).


METHODS
Patients with a risk of more than 15% lymph node involvement were included. For treatment planning, SN localizations were included into the pelvic clinical target volume. Dose prescriptions were 50.4 Gy to the adjuvant area and 70.0 Gy to the prostate. All treatment plans were generated using equivalent uniform dose (EUD)-based optimization algorithms and Monte Carlo dose calculations and compared with 3D conventional plans.


RESULTS
A total of 25 patients were treated and 142 SN were detectable (mean: n = 5.7; range, 0-13). Most SN were found in the external iliac (35%), the internal iliac (18.3%), and the iliac commune (11.3%) regions. Using a standard CT-based planning target volume, relevant SN would have been missed in 19 of 25 patients, mostly in the presacral/perirectal area (22 SN in 12 patients). The comparison of conventional 3D plans with the respective IMRT plans revealed a clear superiority of the IMRT plans. No gastrointestinal or genitourinary acute toxicity Grade 3 or 4 (RTOG criteria) occurred.


CONCLUSIONS
Distributions of SN are highly variable. Data for SN derived from single photon emission computed tomography are easily integrated into an IMRT-based treatment strategy. By using SN data the probability of a geographic miss is reduced. The use of IMRT allows sparing of normal tissue irradiation.
Ganswindt
Ute
U
Department of Radiation Oncology, University of Tuebingen, Tuebingen, Germany.
Paulsen
Frank
F
Corvin
Stefan
S
Hundt
Ilse
I
Alber
Markus
M
Frey
Bettina
B
Stenzl
Arnulf
A
Bares
Roland
R
Bamberg
Michael
M
Belka
Claus
C
D000465:Algorithms; D012809:Colon, Sigmoid / Q000528:radiation effects; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D009010:Monte Carlo Method; D009367:Neoplasm Staging; D010388:Pelvis; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012007:Rectum / Q000528:radiation effects; D001743:Urinary Bladder / Q000528:radiation effects
D017430:Prostate-Specific Antigen