Most radiotherapists include the lymph node regions when they design fields to radiate the prostate. Long term results if the nodes are involved is poor (Hanks) and the RTOG trials showed little or no benefit from including the nodes.
 

Int J Radiat Oncol Biol Phys 1988 Dec;15(6):1307-16

Elective pelvic irradiation in stage A2, B carcinoma of the prostate: analysis of RTOG 77-06.

Asbell SO. From 1978 to 1983 the Radiation Therapy Oncology Group conducted a study to evaluate the role of elective pelvic lymph node irradiation in carcinoma of the prostate. Eligible patients were those with clinical Stage A2 (occult disease with more than 3 positive chips and poorly differentiated tumor) and Stage B without clinical (lymphangiogram) or biopsy evidence of lymph node involvement. The patients were randomized to receive 6.5 weeks of either prostatic bed irradiation only 6500 cGy at 180-200 cGy per treatment or pelvic node irradiation to 4500 cGy with a boost of 2000 cGy to the prostatic bed bringing the total dose to 6500 cGy. As of February, 1988, the median follow up has been 7 years and there were 445 analyzable cases who were evaluated for local control, incidence of distant metastases, ned (no evidence of disease) survival and survival. The results of the study revealed no statistically significant benefit of elective pelvic irradiation.

Int J Radiat Oncol Biol Phys 1986 Mar;12(3):345-51

Extended field (periaortic) irradiation in carcinoma of the prostate--analysis of RTOG 75-06.

Pilepich MV. From 1976 to 1983 the Radiation Therapy Oncology Group conducted a study of extended field (periaortic) irradiation in carcinoma of the prostate. Eligible patients were those with clinical Stage C tumor with or without evidence of pelvic lymph node involvement and also those with Stage A-2 and B with evidence of pelvic lymph node involvement. The patients were randomized to either receive pelvic irradiation followed by a boost to the prostate or pelvic and periaortic irradiation followed by a boost to the prostate. The prescribed daily dose was 180-200 rad to a total midplane dose to the regional lymphatics to 4000-4500 rad. The prostatic boost target volume was to receive additional 2000-2500 rad bringing the total dose to that area to a minimum of 6500 rad. No statistically significant differences between the treatment arms could be documented. Similarly, no significant difference between treatment arms could be documented within a number of subpopulations such as those characterized by a particular grade, hormonal status, stage, age, acid phosphatase level, etc. The results of the study revealed no apparent benefit of elective periaortic irradiation in patients with detectable disease confined to the pelvis.

Int J Radiat Oncol Biol Phys 1998 Mar 1;40(4):765-8

Ten-year outcomes for pathologic node-positive patients treated in RTOG 75-06.

Hanks GE. This study was conducted to see what fraction of prostate cancer patients with biopsy-proven nodes are free of cancer 10 years after radiation treatment. METHODS AND MATERIALS: RTOG protocol #75-06 included 90 patients with biopsy-proven pelvic nodal involvement treated with radiation. They have been continuously follow-up since treatment. When feasible, current prostate-specific antigen (PSA) levels have been solicited from patients clinically cancer-free (no evidence of disease, NED) at 10 years, to confirm cure. RESULTS: The 10-year survival was 29%, the 10-year clinical NED survival 7%.

NCI Monogr 1988;(7):61-5

Radiation Therapy Oncology Group studies in carcinoma of the prostate.

Pilepich MV. From 1976 to 1983, the Radiation Therapy Oncology Group (RTOG) conducted 2 large-scale phase III trials of extended field irradiation in patients with carcinoma of the prostate. The first, RTOG 75-06, was designed to test the value of elective periaortic irradiation in patients in whom the tumor extended beyond the gland, but remained limited to the pelvis, and the second, RTOG 77-06, was designed to test the value of elective pelvic irradiation in patients without evidence of spread beyond the prostate. The results indicated no apparent benefit from elective periaortic irradiation in patients with detectable disease confined to the pelvis and no apparent benefit from elective pelvic irradiation in patients with detectable disease confined to the prostate. Patients with extracapsular extension of the primary tumor and evidence of pelvic lymph node involvement demonstrated an outcome comparable to that in patients without evidence of lymphatic involvement. This observation may reflect a beneficial effect of pelvic irradiation in patients with nodal involvement. In contradistinction to elective irradiation of regional lymphatics, therapeutic irradiation (of the involved lymphatics) may prove strongly indicated. A prospective study testing this contention needs to be conducted.

Oncology (Huntingt) 1998 Oct;12(10):1467-72; discussion 1472, 1475-6

Does pelvic irradiation play a role in the management of prostate cancer?

Stock. Studies of prostate irradiation with and without inclusion of the pelvic lymph nodes show poor outcomes for node-positive patients, supporting the concept that many of these patients have systemic disease at presentation. Although no randomized trial has examined the role of pelvic irradiation in pathologically node-positive patients, available data fail to reveal any significant benefit of this approach over prostate-alone irradiation. More promising therapeutic approaches involve the combination of local therapy and sustained hormonal therapy. Series comparing prophylactic irradiation of the pelvis and prostate to irradiation of the prostate alone have shown no clear benefit of pelvic irradiation. Pelvic irradiation may play a role in the treatment of early-stage or occult nodal disease, although this has yet to be examined.

Strahlenther Onkol 1998 May;174(5):231-6

Locally advanced prostate carcinoma (T2b-T4 N0) without and with clinical evidence of local progression (Tx N+) with lymphatic metastasis. Is radiotherapy for pelvic lymphatic metastasis indicated or not?


Wiegel . There is a greater controversy regarding the indication of radiotherapy of the pelvic lymphatics in patients with suspected lymph node metastases in locally advanced prostate cancer (T2b-4 N0) on the one hand and in patients with pathologically proven lymph node metastases in locoregional advanced prostate cancer (Tx pN+) on the other hand following definitive radiotherapy and radical prostatectomy. the RTOG conducted 2 prospective randomised studies (RTOG 75-06, 77-06) to address these questions. However, the results of these studies showed no better survival or cause specific survival for patients treated for the paraaortal or pelvic lymphatics and therefore, radiotherapy of the pelvic lymphatics was no more advocated. A reanalysis showed several problems of the study design and it was concluded that the studies couldn't prove the question of elective radiotherapy of the pelvic lymphatics.  Today there is no indication for treating the paraaortal lymphatics in patients with locoregional advanced prostate cancer. Many radiotherapists perform the elective radiotherapy of pelvic lymphatics when the risk of metastases is above 15 to 20% because retrospective data indicate a better outcome. On the other hand, many others don't treat them because RTOG 75-06 and 77-06 didn't demonstrate a better outcome. In case of radiotherapy of the pelvic lymphatics a dose of 45 Gy for suspected metastases and 50.4 Gy for proven metastases is recommended

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