Japanese Journal of Clinical Oncology 34:131-136 (2004)
© 2004 Foundation for Promotion of Cancer Research
Radical External Beam Radiotherapy for Prostate Cancer in Japan: Preliminary Results of the Changing Trends in the Patterns of Care Process Survey between 1996–1998 and 1999–2001
1 Department of Radiology, University of the Ryukyus, Okinawa, 2 Department of Molecular and Surgical Oncology, Medical Institute of Bioregulation, Kyushu University, Beppu, Kyushu, 3 Department of Clinical Radiology, Kyushu University, Fukuoka, 4 Department of Medical Physics and Engineering, Osaka University, Osaka, 5 Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka and 6 Department of Radiation Oncology, Osaka University, Osaka, Japan
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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Objective: To report the preliminary results of a study to delineate the changing trends in radical external beam radiotherapy usage for prostate cancer between the 1996–1998 and 1999–2001 survey periods in Japan.
Methods: The 1996–1998 Patterns of Care Study (PCS) and the 1999–2001 PCS in Japan reviewed the detailed information on 694 patients with prostate cancer treated with radiotherapy. Of them, 298 patients with clinically localized prostate cancer treated with radical external beam radiotherapy in A1 and B1 institutions were selected for analysis (1996–1998 PCS, 117 patients; 1999–2001 PCS, 181 patients).
Results: High-risk prostate cancer (defined as T3–T4 tumors, a pretreatment prostate-specific antigen level >20 ng/ml, and/or poorly differentiated adenocarcinoma) was diagnosed in 82.1% of the patients in the 1996–1998 PCS and in significantly less (70.2%) of those in the 1999–2001 PCS (P = 0.021). Moreover, significantly earlier T stages (T1–T2: 49.7%) and more well-differentiated tumors (24.7%) were found between 1999 and 2001 than between 1996 and 1998 (T1–T2: 31.9%, well-differentiated tumors: 13.9%). Although only 6.1% of patients were treated with radiotherapy by patient’s choice in 1996–1998, a larger proportion (32.2%) chose this treatment in 1999–2001. The median radiation dose was 65.0 Gy (range, 24–74 Gy) in 1996–1998 and increased to 69 Gy (range, 14–80 Gy) in 1999–2001. The percentage of radiation doses <60 Gy was 20.5% in 1996–1998 but only 2.2% in 1999–2001. Moreover, the incidence of treatment with total doses of 
70 Gy was higher in 1999–2001 (43.9%) than in 1996–1998 (19.7%). These increased radiation doses were predominantly observed in B1 institutions. Although the usage of 10 MV was significantly increased in 1999–2001 (82.0%) compared with that in 1996–1998 (65.8%), conformal therapy administered to 52.1% of patients in 1996–1998 was almost the same (55.8%) in 1999–2001. The median number of full-time equivalent (FTE) radiation oncologists (2.4 in A1 institutions and only 0.6 in B1 institutions) in 1996–1998 increased slightly in 1999–2001 (2.7 in A1 institutions, 0.7 in B1 institutions), but remained low in B1 institutions.
Conclusions: In Japan, there is a trend to fewer high-risk prostate cancer patients being treated with radical external beam radiotherapy. An increasing percentage of patients chose radiotherapy and also increased radiation doses, which might reflect the growing acceptance of radical external beam radiotherapy as a treatment of choice for prostate cancer in Japan. Therefore, to optimize delivery of radiotherapy, more advanced equipment and more FTE radiation oncologists are warranted.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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The Patterns of Care Study (PCS) national survey is a retrospective study designed to establish the national practice process of therapies for selected malignancies over a specific time period (1–3). In addition to documenting the practice process, the PCS is important in developing and disseminating national guidelines for cancer treatment. This helps to promote a more uniform care process in the country. The PCS is also designed to complement clinical trials which enhance the standard of care for cancer patients (1,4).
To improve the quality of radiation oncology, the PCS has been imported to Japan from the USA (5,6). The Japanese PCS Working Group on Prostate Cancer started a nationwide process survey for patients who underwent radiotherapy between 1996 and 1998. Subsequently, a second PCS (1999–2001) of patients treated between 1999 and 2001 was conducted and we reported the preliminary results of that PCS for radical external beam radiotherapy in prostate cancer patients in Japan (7–9).
Over the past 10 years, there have been the remarkable changes in prostate cancer treatment policy in Japan. Since entering the prostate-specific antigen (PSA) era, it is possible to detect earlier stages of prostate cancer and there is a better chance of successfully treating early-stage patients with prostate cancer than ever before. Moreover, the use of radical external beam radiotherapy for prostate cancer has been rapidly increasing recently, because a significant amount of new radiation treatment planning technology and methodology has become available. Therefore, to treat Japanese prostate cancer patients optimally, it is important to detect properly the intrinsic changes in the national practice process of radiotherapy for prostate cancer in Japan. In this paper, we report the preliminary results of our study to delineate the changing trends in the process of care for prostate cancer patients treated with radical external beam radiotherapy between the 1996–1998 and 1999–2001 survey periods in Japan.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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The 1996–1998 and the 1999–2001 PCS in Japan reviewed the detailed information on 694 patients with prostate cancer treated with radiotherapy during the respective survey periods (1996–1998 PCS, 307 patients; 1999–2001 PCS, 387 patients). The PCS carried out an extramural audit survey, using a stratified two-stage cluster sampling design. The Japanese PCS developed an original data format in collaboration with the American College of Radiology (ACR, Philadelphia, PA). The PCS surveyors consisted of 20 radiation oncologists from academic institutions. For each institution, one radiation oncologist visited and surveyed data by reviewing patients’ charts. To validate the quality of collected data, the PCS utilized an Internet mailing list including all the surveyors. In-site real-time checks and adjustments of the data input were available to each surveyor and the PCS committee (10).
The following eligibility criteria were used in the current survey: the patients were required to have adenocarcinoma of the prostate without evidence of distant metastasis; they had to have been treated with radiotherapy during the 1996–1998 (1996–1998 PCS) and 1999–2001 (1999–2001 PCS) survey periods; and they should not have received diagnosis of any other malignancy or been previously treated with radiotherapy. Patients who had received prior prostatectomy and patients with hormone-refractory prostate cancer were excluded from this analysis.
The criteria for both the 1996–1998 and 1999–2001 institutional stratifications, on the basis of the Japanese facility master list (11,12), are detailed in Table 1. In the current study, the 1999–2001 PCS was a preliminary study of data gathered only from investigating A1 and B1 institutions and by a two-stage cluster sampling scheme (8). Therefore, in the current study, 298 patients with clinically localized prostate cancer treated with radical external beam radiotherapy in A1 and B1 institutions were selected for analysis (1996–1998 PCS, 117 patients from 22 institutions; 1999–2001 PCS, 181 patients from 36 institutions).
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For this analysis, patients with either T3 or T4 tumors, a pretreatment PSA level >20 ng/ml and/or poorly differentiated tumors were defined as high-risk disease patients. Statistical analyses were performed using the Statistical Analysis System at the PCS data center (13). Statistical significance was tested using the chi-squared test, Student’s t-test and the Mann–Whitney U-test. A probability level of 0.05 was chosen for statistical significance.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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Patients’ and Disease Characteristics
High-risk prostate cancer (defined as T3–T4 tumors, a pretreatment PSA level >20 ng/ml, and/or poorly differentiated adenocarcinoma) was diagnosed in 82.1% (96 of 117 patients) in the 1996–1998 PCS and in significantly fewer (70.2%, 127 of 181 patients) in the 1999–2001 PCS (Table 2, P = 0.021).
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Patient and disease characteristics in the 1996–1998 and 1999–2001 PCSs are shown in Table 3. Significantly earlier T stages (T1–T2, 49.7%, P < 0.0001) and more well-differentiated tumors (24.7%, P = 0.0349) were found between 1999 and 2001 than between 1996 and 1998 (T1–T2, 31.9%, well-differentiated tumor, 13.9%). Table 3 also indicates the reasons for selection of radiotherapy during these different periods. In 1996–1998, only 6.1% (6 of 99) of the patients were treated with radiotherapy by patient’s choice. On the other hand, patient’s choice became one of the main reasons for this treatment between 1999 and 2001 (32.2%, 56 of 174 patients), which are significantly different (statistical analysis only in terms of ‘patient choice’: P < 0.0001).
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Treatment Characteristics
Treatment characteristics are shown in Table 4. The use of
10 MV was significantly increased (P = 0.0015) in the 1999–2001 PCS (82.0%) compared with that in the 1996–1998 PCS (65.8%). On the other hand, the rates of CT simulator (P = 0.5774) and conformal therapy administration (P = 0.5351) were not significantly different and conformal therapy administered to 52.1% of patients in 1996–1998 was almost same (55.8%) in 1999–2001. The median radiation doses in 1996–1998 and 1999–2001 were 65 and 69 Gy, respectively. The percentage of radiation dose <60 Gy was 20.5% in the 1996–1998 PCS but only 2.2% in the 1999–2001 PCS (Fig. 1). Moreover, the incidence of treatment with total doses of 70 Gy was higher in 1999–2001 (43.9%) than in 1996–1998 (19.7%). These increased radiation doses were predominantly observed in B1 institutions (Table 4).
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In both the 1996–1998 and 1999–2001 survey periods, hormonal therapy was commonly used before, during and after radiotherapy with a mean duration of 1.01 ± 1.04 and 1.31 ± 1.03 years, respectively (83.6% of patients in 1996–1998, 88.9% of patients in 1999–2001, P = 0.1908). In contrast, chemotherapy in general was not administered in both periods and significantly less in 1999–2001 (1996–1998, 14.9%; 1999–2001, 6.6%, P = 0.0295).
Full-time Equivalent (FTE) Radiation Oncologists
In the 1996–1998 PCS, the median number of FTE radiation oncologists was 2.4 in A1 institutions and only 0.6 in B1 institutions. In the 1999–2001 PCS, the median number of FTE radiation oncologists slightly increased (2.7 in A1 institutions, 0.7 in B1 institutions).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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This study indicates that Japanese prostate cancer patients treated with radical external beam radiotherapy had significantly less high-risk diseases in 1999–2001 than 1996–1998. Moreover, significantly early primary stage and more well-differentiated tumors were found in 1999–2001 than in 1996–1998. These results suggest that the chances of treating earlier stage prostate cancer patients with radiotherapy are greater than ever before in Japan. Because of the prevailing use of PSA and the increasing number of patients treated with radiotherapy in Japanese institutions (14), the opportunities for treating early-stage prostate cancer patients with radical external beam radiotherapy will increase even more in the future. Recently, interstitial radiotherapy has also been used increasingly in the management of men, with early-stage prostate cancer both in the USA and Japan (15,16). However, at the time of this analysis, only 5.4% (1996–1998 PCS: 307 patients) and 1.1% (1999–2001 PCS: 387 patients) of all patients were treated with interstitial radiotherapy. Therefore, after we have accumulated the data from greater numbers of patients, we will report updated results of interstitial radiotherapy.
This study also revealed that there was a remarkable change in the reason for choosing radiotherapy in Japan between the 1996–1998 and 1999–2001 survey periods. Although only 4.9% of the patients were treated with radiotherapy by their own choice in 1996–1998, 34.6% of patients chose radiotherapy in 1999–2001. External beam radiotherapy did not become a popular treatment modality for prostate cancer in Japan until the end of the 1990s. A strong surgical tradition and an inadequate number of radiation oncology centers prevented earlier dissemination of this type of therapy. However, significant amounts of new radiation treatment planning technology and methodology are now available and Japanese patients have recently become aware of the effectiveness of radiotherapy for prostate cancer (17). Therefore, the increasing percentage of those choosing radiotherapy might reflect acceptance of radical external beam radiotherapy as a treatment of choice for prostate cancer patients in Japan.
Moreover, radiotherapy strategy appears to have changed between the 1996–1998 and 1999–2001 survey periods. The radiation doses were higher in the 1999–2001 PCS (median, 69 Gy) than in the 1996–1998 PCS (65 Gy). The percentage receiving radiation doses <60 Gy was 20.5% in 1996–1998, but only 2.2% in 1999–2001 (Fig. 1). Furthermore, the percentage of patients treated with total doses of 70 Gy was higher in 1999–2001 (43.9%) than in 1996–1998 (19.7%). These results indicate that lower radiation doses were more common between 1996 and 1998, while higher doses prevailed between 1999 and 2001. The use of increasing radiation dose might reflect the widespread dissemination of clinical trial results (18,19) and also growing acceptance by radiation oncologists and urologists of radical external beam radiotherapy as a main treatment for prostate cancer (20).
However, the national practice process of radiotherapy in Japan was closely related to structural immaturity, especially in terms of equipment and personnel. The rates of CT simulator and conformal therapy administration, technology that not only improves the target volume dose distribution but also concomitantly reduces the normal tissue dose (21), were not significantly different between the 1996–1998 and 1999–2001 survey periods. Especially the rates of conformal therapy remained low (~50%) during these periods. With regard to personnel, the median number of FTE radiation oncologists slightly increased in 1999–2001, but remained low in B1 institutions. On the other hand, the number of prostate cancer patients treated with radiotherapy has increased in every institution over the past few years (14). Therefore, the amount of advanced equipment and the number of radiation oncologists on duty must be increased in Japanese institutions.
By comparing of the results of the 1996–1998 and 1999–2001 PCSs, we can delineate the changes in the process of care for prostate cancer patients treated with radiotherapy in Japan. There was a trend toward less high-risk diseases between 1999–2001 and 1996–1998 and radical external beam radiotherapy has recently become a treatment of choice for prostate cancer in Japan. Therefore, to optimize the delivery of radiotherapy, more advanced equipment and more FTE radiation oncologists are warranted.
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Acknowledgments |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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This work was supported by the Grants-in-Aid for Cancer Research (Grant Nos 10-17 and 14-6) from the Ministry of Health, Labor and Welfare of Japan, Japanese Foundation of Aging and Health, Japan Society for the Promotion of Science, Japanese Cancer Research, Siemens Medical, Toshiba Medical and CMS Japan. We thank all radiation oncologists who participated in this study: their information made these surveys possible. We are grateful for the 9 years of continuous thoughtful support we have received from the US PCS Committee.
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FOOTNOTES |
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+ For reprints and all correspondence: Kazuhiko Ogawa, Department of Molecular and Surgical Oncology, Medical Institute of Bioregulation, Kyushu University, Tsurumihara 4546, Beppu 874-0838, Japan. E-mail: kogawa{at}med.u-ryukyu.ac.jp
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Received November 9, 2003; accepted January 12, 2004
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