Previously we reported that our series of patients (treated between 2004 and 2006) received PADT more frequently than in USA [2
]. Relatively more patients chose PADT as the primary therapy not only for locally advanced prostate cancer but also for localized prostate cancer in Japan [8
]. This nation-wide trend in Japan is apparently dissimilar from that in the Western countries [1
]. According to the JUA report, for example, 57% of the registered patients received PADT, 28% underwent RP with or without neoadjuvant or adjuvant therapy, and 8% received RT with or without neoadjuvant therapy in 2000 [9
]. In comparison between our report and the 2000 JUA report, the proportion of RT in our report was significantly higher than that of JUA report (14% vs. 8%), while the proportion of PADT was significantly lower than that of the JUA report (51% vs. 57%) (p
< 0.001, chi-square test; data not shown). Since low-dose rate brachytherapy was legally approved by the government in 2003, RT overall including high-quality EBRT like intensity modulated radiation therapy and three-dimensional radiation therapy has been increasing no less than brachytherapy in Japan year after year. The proportion of RT is likely to hereafter increase alternatively to PADT in Japan.
Several specific reasons for this trend in Japan are proposed. First, all patients are covered completely by the total public health insurance system in Japan. All patients including even no-income people can receive any therapy they like under the public insurance coverage. In principle, the patients continue PADT until they show androgen independency. The therapy cost increases until cessation of PADT. Secondly, the Japanese patients tolerate well receiving hormonal therapy without severe side effects. Akaza et al
reported that there was no significant difference in the overall survival between the patients with localized prostate cancer treated with PADT and the age-matched men in the general population [12
]. Akaza et al
also reported that the incidence of cardiovascular events in patients treated with leuprorelin was not greater than that expected in the general Japanese population [13
]. On the other hand, the newly diagnosed prostate cancer patients who received PADT for at least one year showed a 20% higher risk of serious cardiovascular morbidity as compared with similar men who did not receive PADT in the SEER database [14
]. Although there is no direct comparison of the cardiovascular morbidity in the patients who receive PADT between Japanese and Western men, serious cardiovascular events are apparently not frequently experienced in the Japanese patients who received hormonal therapy. Thirdly, the majority of the Japanese patients interestingly do not reject receiving hormonal therapy because of the low priority of preserving erectile function at the time of treatment selection. Additionally, most recently robotic surgery was introduced in Japan and robotic-assisted radical prostatectomy is currently available in the several legally authorized hospitals. Since the number of robotic-assisted radical prostatectomy cases has belatedly increased in those limited institutes, the near-future prevalence of this surgical modality will not a little influence selection of less invasive primary therapy for early prostate cancer.
In our data, most primary urologists conceived that RP is the preferential primary therapy for cT1-2N0M0 prostate cancer. Nevertheless, the proportion of patients who actually chose and received RP was 40%, but those who received PADT accounted for nearly 40%. Of course, some patients could not receive the definitive therapy due to several limitations such as co-morbidity, old age and so on. Nonetheless, the proportion of PADT for this clinical stage was higher in Japan than in the Western countries [3
]. Since only 3 affiliated hospitals could provide EBRT, and BT is currently available only in the university hospital, this status strongly affects the different proportions of EBRT and BT between the university hospital and its affiliates. Indeed, the present high proportion of BT and EBRT (over 45%) was attributed to the recent increase in patients who were referred to the university hospital with their own choice for RT.
RP and EBRT were equally selected (42% each) as the preferential primary therapy for cT3aN0M0 prostate cancer. Interestingly, over 40% of urologists considered RP as the preferential therapy for cT3a prostate cancer. However, PADT was the highest with the actual rate of 58%. In the university hospital, 42% of the patients received EBRT and 33% underwent PADT. On the other hand, two-thirds of patients received PADT in the affiliated hospitals. Although 46% of urologists selected EBRT for cT3bN0M0, an unexpectedly high rate (38%) of urologists considered that RP was still the preferential primary therapy. However, two-thirds of the patients actually received PADT while 21% and 9% received EBRT and RP, respectively. In the university hospital, no patients with cT3b prostate cancer underwent RP.
Overall, the proportion of PADT in our data was as high as that of the JUA report [9
]. Relatively a large population of the urologists is likely to choose RP as the preferential primary therapy for cT3 stage. However, the most common primary therapies were RT in the university hospital and PADT in its affiliated hospitals. A small number of the urologists actually still performed RP even for higher stage prostate cancer. Our speculation is that this trend in the affiliated hospitals may be due to retrospection of unpleasant experiences with old-fashioned RT and unawareness of the recent technological advances in RT during their long-term career as urologists. The educational and institutional prevalence of RT, as an alternative to PADT, seems to be necessary for both urologists and patients with advanced prostate cancer in Japan.
Interestingly, the present study showed that the hospitals with lower volume of RP significantly conducted PADT compared with those with higher volume of RP in patients with cT1-3N0M0 (Figure ). RT was available in 1 hospital in Group 2 and all hospitals in Group 3. The proportion of PADT was significantly higher in the hospitals where RT was not available in own hospital than those where RT was available. Recently, Barocas et al
reviewed the available literature on the impact of surgeon and hospital volume on patient outcomes after RP. They reported a substantial advantage (e.g. length of hospital stay, peri-operative complications, peri-operative mortality, treatment failure and so on) for patients treated in high volume hospitals and by high volume surgeons [15
]. It is conceivable that the choice of primary therapy by patients and doctors would depend on the volume of RP and the variety of treatment modalities. Unfortunately, the correlation between high volume hospital and the outcomes in the present study cohort has not been evaluated. A further investigation with substantial follow-up period makes it possible to elucidate this issue.
There were several limitations of this study. First, we used a self-developed questionnaire to determine the preferential therapy by doctors at each clinical stage. This questionnaire has not been externally validated. Second, we did not conduct the survey in patients stratified risk classification. It is more preferable to survey the preferential primary therapy at the moment. Third, this study was lacking in the aspect of co-morbidity of patients. Fourth, it would be more informative if a patient-directed questionnaire were adopted.