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.

Abstract

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. 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). 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 > or =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 > or =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. 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.