Conformal radiotherapy (3D CRT) for non-metastatic androgen-independent prostate cancer: costly and sophisticated but ineffective treatment?

Abstract

Purpose

Patients with diagnosis of hormone-refractory prostate cancers (HRPC) present a very heterogeneous population, and therefore it has been proposed to sub-categorize them into two subgroups depending on presence or absence of distant metastases. While the former subgroup has been typically treated with palliative intention, for the latter apparently there is no standard approach. The role of three-dimensional conformal radiotherapy (3D-CRT) for this subgroup has not been well documented in the literature. Thus, the purpose of this work is to analyze the results of treatment of non-metastatic androgen-refractory prostate cancer (ARPC) with 3D-CRT and to investigate the potential prognostic factors which influenced the results.

Material and Methods

Of 424 patients with diagnosis of localized and locally advanced prostate cancer who were treated between 1999 and 2004 in our centre, forty-three (n=43) patients were classified as non-metastatic ARPC. Distant metastases were excluded by negative bone scan, negative chest X-ray and negative pelvic CT for lymph node metastases. The median pre-hormone therapy PSA (pre-HT PSA) level for this group was 24 ng/ml (range 1 to 120) and 5.7 ng/ml (range 0.06 to 27) at the beginning of radiotherapy (pre-RT PSA). Clinical T stage distribution, defined according to the 2002 AJCC, was as follows: T1c = 12, T2 = 23, and T3 = 8 patients, respectively. Of 44 patients, 39 had a Gleason score of 2-7 and 4 had a Gleason score of 8–10. All patients with diagnosis of non-metastatic ARPC were treated with 3D-CRT with the daily fraction dose of 2 Gy to a median total dose of 68 Gy (range from 60 to 74 Gy). The median duration of androgen ablation therapy before RT was 26 months (range from 7 to 96). The median time of follow-up after 3D-CRT was 27 months (range from 13 to 62) and from the beginning of androgen ablation was 53 months (range from 20 to 158). The following prognostic factors were evaluated in univariate and multivariate analysis: age, pre-HT PSA, pre-RT PSA, Gleason score, total dose, PSA doubling time (PSADT< 6 months vs. PSADT > 6 months).

Results

The 5-year actuarial overall survival was 82% and 5-year clinical relapse free-survival rate was 49%. During the follow-up 14 patients developed disease progression (locoregional and/or distant and/or biochemical) and two patients died of prostate cancer. The univariate analysis indicated that pre-HT PSA > 20 ng/ml, pre-RT PSA > 4ng/ml, and the high-risk group defined according to NCCN criteria (PSA >20 ng/ml and Gleason score >7) were statistically significant factors for the risk of disease progression.

Conclusions

Three-dimensional conformal radiotherapy for patients with non-metastatic ARPC is a valuable method of treatment for the subgroup of patients with pre-HT PSA<20 ng/ml and Gleason score < 8. For patients classified as the high-risk group according to NCCN criteria 3D-CRT seems to be an ineffective treatment due to the observed high incidence of distant failure, and should be viewed as costly and sophisticated yet ineffective intervention. For this subgroup a systemic modality of treatment such as chemotherapy or biological manipulation should be considered.