Optimized conformal paraaortic lymph node irradiation is not associated with enhanced renal toxicity.

BACKGROUND AND PURPOSE: For patients with gynecologic carcinomas, irradiation of paraaortic lymph nodes (PLNs) is a routine treatment concept. Planning target volumes (PTVs) individually optimized by radiation field delineations along the big vessels permit the inclusion of at least 97% of potentially involved PLNs. However, this novel treatment technique might increase radiation-induced nephrotoxicity. Therefore, the actual incidence of kidney damage after PLN irradiation has to be assessed in order to validate the safety of this treatment concept. PATIENTS AND METHODS: 19 patients were treated with irradiation alone (50.4 Gy; 5 x 1.8 Gy/week) and monitored for up to 90 months. Functional renal parameters, namely renal plasma flow (RPF) and glomerular filtration rate (GFR), were assessed by dynamic renal scintigraphy. Additionally, patients were clinically observed (i.e., hypertension, proteinuria) and calculations of normal-tissue complication probability (NTCP) values for nonuniform kidney irradiation were performed using the Lyman-Wolbarst algorithm. RESULTS: Two patients with anticipated moderate NTCP values (12.6% and 8.7%) showed slightly impaired RPF rates at 12, 24, and after 48 months of follow-up. Only one patient in the subgroup showing NTCP values > 50% (n = 9) developed a notable impairment of renal RPF. However, all patients including those with elevated complication probabilities exhibited neither impaired GFR nor clinically apparent symptoms related to a loss of functioning renal tissue from 12 to > 48 months post irradiation. CONCLUSION: Conformal irradiation of retroperitoneal lymph nodes with individual PTV delineation appears not to be associated with clinically relevant functional impairment of the kidneys.

Single-institution results of primary external-beam radiation for the treatment of t1-t3 prostate cancer.

PURPOSE: To evaluate survival and toxicity rates after primary external-beam radiation for the treatment of prostate cancer. PATIENTS AND METHODS: Data of 306 patients treated with conformal external beam radiation between 1996 and 2001 were collected. These were evaluated in terms of overall, cause-specific and disease-free survival as well as toxicity. Furthermore, an investigation of possible risk factors was performed. RESULTS: Toxicity rates compared favorably with other series with 5.2% RTOG 1-2 and no RTOG > 2 long-term side effects. Actuarial 5-year overall survival rates with and without biochemical failure were 77% versus 78%, cancer-specific survival was 85.41% versus 100%, and disease-free survival was 71.54%, respectively. Potential risk factors for cancer-related death were biochemical failure, initial serum prostate-specific antigen (PSA) and Gleason score. CONCLUSION: Toxicity rates were found to be surprisingly low compared to other series, which is likely due to low daily dose and consistent MR-based treatment planning. In terms of survival, no significant differences to other trials could be observed. Initial PSA and Gleason score were significant predictors for treatment outcome in terms of survival.

Competing irradiation techniques for para-aortic lymph nodes: dose distribution and NTCP for the kidney.

PURPOSE: Partial coirradiation of both kidneys is an unavoidable consequence of adequate dose delivery in radiation therapy of para-aortic lymph nodes (PLN). Depending on total dose anteroposterior/posteroanterior (AP/PA), opposed-fields or multifield techniques are used. To optimize the treatment of potentially tumor-affected PLN with minimal kidney involvement, we calculated normal tissue complication probabilities (NTCPs) of coirradiated kidneys for four common irradiation techniques used in the PLN area. METHODS AND MATERIALS: Planning target volume (PTV) delineation was performed in computed tomography scans of 21 patients with a lateral safety margin of 3 cm from the aorta and 2 cm aside the vena cava. Ventral and dorsal margins of the PTV were delineated 2 cm from the vessels. As previously shown (Nevinny-Stickel M, et al. Int J Radiat Oncol Biol Phys 2000;48:147-151), PTVs optimized by these altered delineations permit inclusion of at least 97% of potentially involved PLN in contrast to standard delineations based on bony structures that are more likely to miss affected lymph nodes. The present study compared NTCPs for individual PTV-based treatment planning with NTCPs for standard planning based on bony structures. For each patient, four hypothetical treatment plans were created: (A) standard AP/PA opposed fields technique with lateral field margins along the tips of the transverse processes of the vertebral bodies; (B) individually planned AP/PA opposed fields with lateral field margins according to the optimized PTV; (C) standard four-field box technique with lateral width as described for (A), with dorsal borders at the center of the vertebral bodies and ventral margins 3 cm in front of the vertebrae; and (D) individually planned four-field box with lateral field margins according to the optimized PTV. Calculation of irradiation-induced complication probability values for nonuniform kidney irradiation was performed for model doses 19.8 Gy, 30.6 Gy, and 50.4 Gy according to the Lyman-Wolbarst model. RESULTS: No dose showed a statistically significant difference (p < 0.00833, corrected for six multiple interrelated comparisons) in the median of total organ kidney NTCPs between techniques A, C, and D, with technique D intermediately ranging between technique A and C (e.g., for 50.4 Gy: A: median, 0.39; range, 0.01-0.83; C: median, 0.27 range; 0.05-0.68; D: 0.36; range, 0.03-0.72). In comparison to techniques A, C, and D, the individually planned AP/PA opposed-fields technique (B) was accompanied by significantly higher and intolerable overall kidney NTCP rates (e.g., for 50.4 Gy: median, 0.68; range, 0.01-0.99). CONCLUSION: Conformal four-field planning with individually optimized PTVs (D) resulted in only moderate tissue complication probabilities in both kidneys with the advantage of providing significantly greater inclusion of potentially involved PLNs in comparison to accepted standard procedures (A and C).