(P054) Carbon Ion Therapy for Chinese Patients With Prostate Cancer: Primary Reports

Shen Fu, Qing Zhang, Xiaomeng Zhang, Xin Cai, Jin Meng, Jingfang Zhao, Yinxiangzi Sheng, Kambiz Shahnazi, Michael F. Moyer; Shanghai Proton and Heavy Ion Center/Fudan University Shanghai Cancer Center; Shanghai Proton and Heavy Ion Center; Shanghai Jiao Tong University Affiliated Sixth People’s Hospital

PURPOSE: To evaluate the toxicities and efficacy of carbon ion therapy for patients with prostate cancer.

MATERIALS AND METHODS: A total of 19 patients with pathologically confirmed prostate cancer were treated with carbon ion therapy from June 2014 to September 2014; 2 had low-risk, 10 had intermediate-risk, and 7 had high-risk prostate cancer. The patients with intermediate-/high-risk disease received neoadjuvant hormone therapy for 2–3 months, followed by concurrent hormone and carbon ion irradiation (63–66 GyE/23–24 Fx with one fraction per day, 5 days per week). The target area included the prostate and partial seminal vesicle, depending on the prognostic risk. Cone-down strategy was adapted in order to avoid the toxicities of the bladder and rectum. Peripheral blood was withdrawn before, during, and after carbon ion therapy.

RESULTS: Immediate outcome: Prostate-specific antigen (PSA) was used to evaluate the response to carbon ion therapy: 7 of 19 (37%) patients had biochemical control (PSA < 0.1 ng/mL) just after the conclusion of carbon ion therapy, and PSA values will be used to determine efficacy of the treatment 3 months after treatment. Also, 7 of 19 patients were diagnosed with abnormal 11 choline–positron emission tomography-computed tomography (PET-CT) before carbon ion therapy. Therefore, 11 choline–PET-CT will be conducted for those patients 3 months after treatment, and the data will be available at the time of the ARS meeting. A total of 7 of 19 patients had statistically higher apparent diffusion coefficient (ADC) values detected by diffusion-weighted imaging (DWI) before radiotherapy than after treatment (P = .0049). Circulating tumor cells (CTCs) in peripheral blood samples could be detected in 7 of 19 patients before carbon ion therapy, but there were no CTCs in 6 of these 7 patients after treatment.

A total of 6 of 19 (32%) patients had variable acute toxicities per the Common Terminology Criteria for Adverse Events version 4.03 (CTCAE v4.03): hematologic system (5), genitourinary (GU) (4), and gastrointestinal (GI) (1). Most toxicities were grade 1; two patients had grade 2 hematologic toxicities. There were no significant differences in specific immunity (T cells: CD3, CD4, CD8 for cellular immunity; B cells: CD19 for humoral immunity) or nonspecific immunity (NK cells: CD16, CD56) before and after carbon ion therapy.

CONCLUSION: This is the first report about a Chinese population with prostate cancer treated with carbon ion therapy. Our primary data showed that carbon ion therapy was well tolerated, and the immediate effect was encouraging. Long-term follow-up is needed for the analysis of final treatment responses and toxicities.

Proceedings of the 97th Annual Meeting of the American Radium Society- americanradiumsociety.org