Efficacy and Safety of Newly Installed Spot Scanning Proton Beam Therapy for Prostate Cancer.

BACKGROUND/AIM: This study aimed to analyse retrospectively the initial treatment outcomes and associated toxicities of a spot scanning proton beam therapy for prostate cancer at the Shonan-Kamakura General Hospital.

PATIENTS AND

METHODS

A laterally opposing single-field uniform dose of spot-scanning proton beam was used. The doses were determined to be 60 Gy in 20 fractions for low-risk prostate cancer and 63 Gy in 21 fractions for intermediate- and high-risk prostate cancers. Genitourinary (GU) and gastrointestinal (GI) toxicities were also evaluated. Toxicity was assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

RESULTS

A total of 135 patients were treated over two years, 51 of whom underwent hydrogel spacer insertion. During the limited observation period, no patient experienced a recurrence. Grade 2 GU toxicities were observed in 17 patients, whereas grade 1 or greater GI toxicities were observed in seven patients. None of the patients in whom a hydrogel spacer was inserted experienced grade 1 or higher GI toxicity.

CONCLUSION

Proton beam therapy is safe for the treatment of prostate cancer. The insertion of a gold marker and hydrogel spacer led to a reduction in the rectal radiation dose and GI toxicity.