Study reveals treatment trends for prostate cancer in Japan

By Joanna Lyford, Senior medwireNews Reporter

There has been a recent increase in use of radiotherapy in Japanese men newly diagnosed with prostate cancer and a concomitant decrease in use of androgen deprivation therapy (ADT), study findings indicate.

The trends were identified by Mizuki Onozawa (Tokyo-Kita Medical Center, Japan) and colleagues and are reported in the Japanese Journal of Clinical Oncology.

For their study, the researchers reviewed initial treatment choices in 8291 men across Japan with prostate cancer. All men had newly diagnosed biopsy-proven disease and were started on treatment during 2010.

The men’s mean age was 71 years, 40.5% had T1c stage disease and 10.4% had M1 disease. The proportion classified as low-, medium- and high-risk using D’Amico’s classification system was 19.3%, 29.8% and 25.9%, respectively. One-quarter of the men had locally advanced, metastatic disease or both.

The most common initial treatment was ADT, given in 40.2% of cases, followed by radical prostatectomy in 32.0%, radiation in 21.0% (brachytherapy in 40.6% of these cases) and active surveillance in 6.4%.

By way of comparison, the respective values in a Japanese study performed in 2004 were 49.8% for ADT, 31.5% for radical prostatectomy and 10.4% for radiation, indicating an increase in the use of radiation and a decrease in ADT.

“Even when differences in the background characteristics were taken into account, this trend of increased use of radiation and decreased use of ADT was still confirmed especially in localized disease,” write the authors.

In the subgroup of patients with T1 disease, initial therapy was radical prostatectomy, radiation and ADT in 36.8%, 25.7% and 25.0%, respectively, of patients in 2010 versus 39.0%, 13.7% and 38.4%, respectively, in 2004.

Onozawa and co-authors say their data indicate that a trend towards more “definitive/curative but still conservative treatments” may be emerging in Japan. This may be driven, at least in part, by the increased use of brachytherapy and other new radiation modalities, which carry a lower burden in terms of adverse events.

“[F]urther longitudinal studies would be needed to confirm the aforementioned trend,” the authors remark.

Although the overall popularity of radical prostatectomy did not change significantly between 2010 and 2004, there has been an increase in laparoscopic procedures and a corresponding decrease in open surgery. Nevertheless, the open approach was the most widely used option in 2010, accounting for 77.3% of cases.

The authors conclude: “[T]he increased proportion of radiation and the high proportion of ADT irrespective of the disease stage were features of the initial therapy for prostate cancer in Japan.”

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