gms | German Medical Science

48th Meeting of the Particle Therapy Co-Operative Group

Particle Therapy Co-Operative Group (PTCOG)

28.09. - 03.10.2009, Heidelberg

Multi-Institutional Phase II Study of Proton Beam Therapy for Organ Confined Prostate Cancer in Japan, Focusing on the Incidence of Late Rectal Toxicities.

Meeting Abstract

  • K. Nihei - National Cancer Center Hospital East, Kashiwa, Japan
  • M. Onozawa - National Cancer Center Hospital East, Kashiwa, Japan
  • T. Ogino - National Cancer Center Hospital East, Kashiwa, Japan
  • S. Murayama - Shizuoka Cancer Center, Shizuoka, Japan
  • H. Fuji - Shizuoka Cancer Center, Shizuoka, Japan
  • M. Murakami - Hyogo Ion Beam Medical Center, Tatsuno, Japan
  • Y. Hishikawa - Hyogo Ion Beam Medical Center, Tatsuno, Japan

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog150

DOI: 10.3205/09ptcog150, URN: urn:nbn:de:0183-09ptcog1507

Published: September 24, 2009

© 2009 Nihei et al.
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Outline

Text

Background: Proton beam therapy (PBT) for prostate cancer can provide a good dose distribution using simple bilateral opposed fields without increasing excessive doses to the rectum and bladder. But because the prospective data is lacking, it's not clear if PBT can clinically reduce the toxicities. We started a multi-institutional phase II trial focusing on the incidence of late grade 2 or greater rectal toxicity.

Material and methods: The major eligibility criteria included, 1) clinical stage T1-2N0M0, 2) initial PSA of 20 ng/ml or less, and Gleason score (GS) of 7 or less, 3) no hormonal therapy (HT) or HT within 12 months before registration, and 4) written informed consent. The low and intermediate risk groups in this study were defined as GS <7 and PSA <10, and GS=7 or PSA>10, respectively. Primary endpoint was the incidence of late grade 2 or greater rectal toxicity at 2 years. The sample size was set of 150, so that its upper limit of 95% confidence interval (CI) should be below 16% when the actual incidence is below 10%. Three institutions providing PBT in Japan participated in this study after each institutional review board approved this study. PBT was delivered to a total dose of 74 GyE in 37 fractions. The target volumes were defined as the prostate alone for low risk patients, and the prostate and proximal seminal vesicles for intermediate risk patients. Patients were prospectively followed up to collect the data of toxicities and PSA values one month and every 3 months after the completion of PBT for the first 2 years, and every 6 months thereafter. NCI-CTC version 2.0 was used to assess both acute and late toxicities.

Results: From March 2004 to March 2007, 151 patients were enrolled in this study. Patients characteristics were as follows: low risk/intermediate risk, 77/74; T1c/T2a/T2b/T2c/T3a, 75/49/9/17/1; Gleason score 4/5/6/7, 5/15/80/51; iPSA <10/10–20, 102/49; HT/no HT, 42/109. The median follow-up period among all patients is 43.4 months (range: 3–62). Four patients were lost to follow-up within 2 years. Acute grade 2 rectal and bladder toxicities temporarily occurred in 0.7% and 12%, respectively. Of 147 patients who had been followed up for more than 2 years, late grade 1/2/3 rectal and bladder toxicities were observed in 27/5/0 (18.4%/3.4%/0%) patients and in 9/8/2 (6.1%/5.4%/1.4%) patients, respectively. The incidences of late grade 2 or greater rectal toxicities were 2.0% (95% CI; 0%, 4.3%) at 2 years (primary endpoint), and 4.1% (95% CI; 0.4%, 7.7%) at final follow-up. The corresponding figures in terms of bladder toxicities were 4.1% (95% CI; 0.9%, 7.3%) at 2 years, and 7.8% (95% CI; 2.9%, 12.8%) at final follow-up.

Conclusion: These results of this prospective study show the evidence that PBT for organ confined prostate cancer can achieve low incidence of both acute and late toxicities.