Background: This is the first study to examine the characteristics and changes of the patterns of radiotherapy for prostate cancer in Japan. Methods: The Japanese Patterns of Care Study (PCS) conducted a random survey of 84 institutions nationwide. Detailed information was collected on prostate cancer patients without distant metastases, who received radiotherapy during 1996-1998 and 1999-2001. Results: The patients were divided into three groups: The Fresh Group (n = 338) was treated with radical radiotherapy with photon beams; the Surgery Group (n = 115) was treated after prostatectomy; and the Hormone-Refractory Group (n = 117) was treated after progression from hormonal therapy. In the Fresh Group, there was a decline in the fraction of patients with T3-4 tumors, from 65.2% in 1996-1998 to 43.9% in 1999-2001. In 1999-2001, a higher median dose of 69 Gy was irradiated as compared to 65 Gy in 1996-1998. In particular, the fraction of the patients treated with doses ≥70 Gy increased from 16.4% to 46.3%. In the Surgery Group, the percentage of clinical T3-4 tumors before prostatectomy decreased from 71.4% in 1996-1998 to 16.2% in 1999-2001. The median radiation dose of 60 Gy did not change, but the 1999-2001 results showed a decrease in the use of doses <60 Gy. In the Hormone-Refractory Group, the median dose increased from 60 Gy in 1996-1998 to 67 Gy in 1999-2001. Conclusion: These data suggest that radiation doses for prostate cancer in Japan have increased dramatically within a short period of time.
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