PT3 and/or positive resection margin prostate adenocarcinoma with undetectable post-operative psa following radical prostatectomy: to irradiate or not

Purpose: To evaluate the efficacy of adjuvant radiotherapy (RT) for pathological T3 (PT3) and/or positive resection margin prostate adenocarcinoma with undetectable post-operative PSA following radical prostatectomy (RP). Materials and Methods: Retrospective, single-institution study. A total of 125 patients, who had PT3 and/or positive resection margin with undetectable post-operative PSA (<0.2 ng/ml) within 6 months following RP, were assessed between 1988 and 1998. At the discretion of the radiation oncologist, 73 patients underwent post-operative adjuvant RT (Group RT) while 52 did not (Group non-RT). In both groups, none except two patients in Group RT received additional therapies such as hormone therapy. In these 2 patients, hormone therapy was used for only 1 month prior to RT and discontinued at the time of initiation of RT. RT doses ranged from 60 to 66 Gy in 30 to 33 daily fractions. A multi-field technique and 10-18 MV photons were used for RT. RT target volume was limited to the prostate bed and peri-prostatic tissue and did not include pelvic lymph nodes. Freedom from relapse was defined as the maintenance of PSA <0.2 ng/ml and the absence of clinical local recurrence and distant metastasis. Cox regression analysis was performed to identify predictive factors for biochemical disease free survival (bDFS). Results: Group RT had statistically significantly higher proportion of patients with Gleason score (GS)≥8 than Group non-RT (34.2% vs. 11.7%). But, the two groups were statistically similar with respect to pathological T stage, resection margin status, and pre-RP PSA (Table). Median age was 62 years for Group RT and 63.5 years for Group non-RT. For Group RT, median follow-ups from RP and RT were 4.2 years (range:1.8-9.8) and 4.0 years (range:1.2–9.4) respectively. For Group non-RT, median follow-up from RP was 4.9 years (range:1.5-12.0). Actuarial 5-year survival rates from RP and RT were 94% and 95% respectively for Group RT. Group non-RT had a similar actuarial 5-year survival rate of 95%. However, 5-year actuarial bDFS was significantly better in Group RT than Group non-RT (90% vs. 75%, p= 0.04). In Group RT, 8 patients (11%) had relapse (all with PSA failure only). None had local recurrence. In Group non-RT, 18 (35%) failed (15: PSA failure only, 1: local recurrence, 2: distant metastasis). The morbidity of adjuvant RT was minimal with only 2 patients developing Grade 3 genitourinary complication. On Cox regression analysis of possible predictive factors for bDFS, pre-RP PSA, and adjuvant RT were statistically significant factors, while GS, pTstage, margin status were not. Conclusion: Post-operative adjuvant RT offered improved bDFS in comparison with observation alone for PT3 and/or positive resection margin with undetectable post-RP PSA. This benefit was observed, despite that fact that there was a higher proportion of patients with GS ≥8 in Group RT. Adjuvant RT and pre-RP PSA were important prognostic factors for bDFS. There was no significant difference in clinical local control; however, this is likely due to relatively short follow-up of our cohort. Adjuvant RT was well tolerated with minimal late toxicity. Up-front adjuvant RT should be considered for PT3 and/or positive resection margin, even when post-RP PSA is undetectable. This is due to increasing evidences suggesting that 1. Post-operative RT offers better local control and bDFS, 2. The morbidity of adjuvant RT is minimal, and 3. The efficacy of salvage RT for rising PSA or clinically palpable local recurrence following RP appears limited. Tabled 1Mean Pre-RP PSA (ng/ml)GS≥8 (%)Positive resection margin (%)PT3a (%)PT3b (%)Group RT (n=73)15.134.2%80.8%52.1%26.0%Group non-RT (n=52)11.211.7%73.1%48.1%19.2% Open table in a new tab