Radical external beam radiotherapy for prostate cancer in Japan: Preliminary results of the 1999-2001 patterns of care process survey

Background: A Patterns of Care Study (PCS) has been conducted to evaluate the standards of practice for prostate cancer patients treated with radiotherapy in Japan. This study examines the influence of institutional stratification on the process of care for patients receiving radical external beam radiotherapy for prostate cancer in the 1999-2001 PCS in Japan. These PCS results were compared with those of the 1999 PCS in the USA. Methods: A national survey of 36 institutions was conducted using two-stage cluster sampling and detailed information was accumulated on 305 clinically localized prostate cancer patients who received radiotherapy between 1999 and 2001. Of these, 181 patients treated with radical external beam radiotherapy were selected and the preliminary results were analyzed. Institutions were classified as A1 (academic institutions treating ≥430 patients a year) or B1 (non-academic institutions treating ≥130 patients a year). Results: In both A1 and B1 institutions, more than 80% of the patients had intermediate or unfavorable risk diseases. There were no significant differences in the patients' disease characteristics between A1 and B1 institutions, while the institutional stratification significantly affected the patterns of radiotherapy; such as the beam energy (≥10 MV, A1 89.9%, B1 72.2%; P = 0.0022), the use of a CT simulator (A1 91.0%, B1 80.0%; P = 0.0340) and the administration of conformal therapy (A1 85.0%, B1 20.5%; P < 0.0001). The median number of full-time equivalent (FTE) radiation oncologists was 2.7 in A1 institutions and only 0.7 in B1 institutions. Median radiation doses of 66.00 Gy (A1 institutions) and 69.00 Gy (B1 institutions) were delivered and hormonal therapy was commonly used before, during and after radiotherapy, with a mean duration of 1.3 years (88.0% in A1 institutions; 90.0% in B1 institutions). In comparing the results of PCS in Japan (1999-2001) with those in the USA (1999), patients in Japan were found to have more advanced primary diseases with higher PSA levels than those in the USA. The median prescribed dose to the primary tumor was not significantly different between the two countries (69.00 Gy in Japan and 70.45 Gy in the USA). Conversely, almost half of the patients in the USA were treated with higher prescription dose levels (≥72 Gy), whereas only 9.4% of the Japanese patients received these dose levels. Hormonal therapy was used more frequently in Japan (88.1% of the patients) than in the USA (50% of the patients). Most of the Japanese patients with a favorable prognosis (72.0%) were treated with hormonal therapy, compared with 30% in the USA. On the other hand, most of the patients in the unfavorable risk group were treated with radiotherapy in conjunction with hormonal therapy both in Japan (91.1%) and the USA (81%). Conclusions: During the period 1999-2001, the majority of the prostate cancer patients treated in Japan with radical external beam radiotherapy had advanced diseases and institutional stratification significantly affected the patterns of radiotherapy. In both academic and non-academic institutions, radiotherapy in conjunction with long-term hormonal therapy was commonly used. In comparison with the 1999 PCS in the USA, Japanese patients had more advanced diseases, but the higher prescribed doses (≥72 Gy) were less common in Japan. Administration rates of hormonal therapy for favorable risk patients were different between Japan and the USA. On the other hand, for unfavorable risk patients, radiotherapy in conjunction with hormonal therapy appeared to be an accepted approach both in Japan and in the USA.