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Purpose To evaluate the distribution of metastatic lymph nodes (LN) detected on 68Ga-PSMA-positron emission tomography/computed tomography (PET/CT) in treatment-naive prostate cancer (PC) patients and to analyze the LN coverage rates of the pelvic fields defined in the GETUG trial and RTOG guidelines and a pelvic field extending superiorly from the L4/L5 interspace. Materials and methods 68Ga-PSMA-PET/CT images obtained at diagnosis of 138 PC patients were retrospectively analyzed. The number and locations of 68Ga-PSMA-positive LNs were co-registered with one single-planning CT. The numbers, locations, and sizes of LNs located outside the three pelvic volumes were investigated for the entire cohort and for patients with LN metastasis in the pelvic area only. Results A total of 441 PSMA-PET-positive LN metastases were identified. The most frequent metastatic LNs were internal iliac LNs (25.2%). Para-aortic and presacral LNs outside the three pelvic fields were present in 20 (14.5%) and 22 patients (15.9%), respectively. The LN coverage rates according to the GETUG trial, the RTOG guidelines, and the pelvic field extending superiorly from L4/L5 were 44.2%, 52.2%, and 71, respectively, in the entire cohort and 51.7%, 61 and 83.1%, respectively, in patients with only pelvic LN metastasis. The number of metastatic LNs was a predictive factor for LNs located outside the three pelvic fields. Conclusions Extending the cranial margin of the pelvic field from L5/S1 to L4/L5 increases the accuracy of pelvic field irradiation in approximately 20% of patients, highlighting the importance of proximal common iliac irradiation, particularly in patients with multiple LN metastasis.

(range: 9 – 82 years). According to the AJCC-1997 staging system, there were 11 (7.6%), 35 (24.3%), 38 (26.4%), and 60 (41.7%) patients in Stage I, II, III, and IV, respectively. There were 57 (39.6%) patients with T1, 41 (28.5%) with T2, 20 (13.9%) with T3, and 26 (18.1%) with T4 tumors. Histopathologic diagnosis was WHO 2–3 in 137 (95.2%) patients. ERT doses ranged between 58.8 and 74 Gy (median: 66 Gy). There were significantly more patients with young age, N2 status, and Stage III disease in Group B and with Stage II disease in Group A. Significantly more patients received chemotherapy in Group B. BRT with an HDR 192 Ir microSelectron afterloading unit was delivered in 106 patients at the conclusion of ERT using a single-channel nasal applicator. Dose was prescribed at 1 cm from the source, and total dose of 12 Gy in 3 fractions on 3 consecutive days was given immediately after ERT. Besides radiotherapy, 82 (56.9%) patients received cisplatin-based chemotherapy, as well. Follow-up time ranged between 12 and 80 months (median: 32 months). Results: The two groups were comparable in terms of local recurrence, locoregional failure, regional failure, and rate of distant metastasis. Local failure was observed in 11 (10.3%) out of 106 patients in Group A and in 2 (5.2%) out of 38 patients in Group B (p > 0.05). Three-year disease-free survival rate was 67% and 80% (p 0.07), respectively, and 3-year local recurrence–free survival rate was 86% and 94% (p 0.23) for Group A and B, respectively. Multivariate analysis showed that advanced nodal status and male gender were significantly unfavorable factors for disease-free survival, and Stage II disease was unfavorable for local recurrence–free survival. The administration of adjuvant HDR BRT was not an independent prognostic factor in multivariate analysis. Out of 106 patients, 42 (39.7%) experienced nasal congestion, transient nasal obstruction, and/or fibrinous exudate in response to antihistaminic treatment. Only three (2.8%) patients experienced nasal synechy related, most probably, to the BRT. Five patients developed severe neural complications; only one out of five was observed in Group A. No severe complication attributed directly to BRT was detected. Conclusion: The acute and late morbidity of adjuvant HDR BRT is acceptable with our treatment scheme, but we did not find any local control difference between our patients treated with adjuvant BRT after ERT and ERT alone. We believe that the exact role of adjuvant HDR BRT can be elucidated only by prospective randomized studies. © 2002 Elsevier Science Inc.