Prostate-specific antigen kinetics after primary stereotactic body radiation therapy using CyberKnife for localized prostate cancer

Yong Hyun Park; In Young Choi; Sei Chul Yoon; Hong Seok Jang; Hyong Woo Moon; Sung-Hoo Hong; Sae Woong Kim; Tae-Kon Hwang; Ji Youl Lee

doi:10.1016/j.prnil.2015.02.003

Prostate-specific antigen kinetics after primary stereotactic body radiation therapy using CyberKnife for localized prostate cancer

Prostate Int. 2015 Mar;3(1):6-9. doi: 10.1016/j.prnil.2015.02.003. Epub 2015 Feb 12.

Authors

Yong Hyun Park¹, In Young Choi², Sei Chul Yoon³, Hong Seok Jang⁴, Hyong Woo Moon¹, Sung-Hoo Hong¹, Sae Woong Kim¹, Tae-Kon Hwang¹, Ji Youl Lee¹

Affiliations

¹ Department of Urology, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Republic of Korea.
² Department of Medical Informatics, The Catholic University of Korea College of Medicine, Seoul, Republic of Korea.
³ Department of Radiation Oncology, Bucheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Bucheon, Republic of Korea.
⁴ Department of Radiation Oncology, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Republic of Korea.

Abstract

Purpose: To assess prostate-specific antigen (PSA) kinetics and report on the oncologic outcomes for patients with localized prostate cancer treated with stereotactic body radiation therapy (SBRT) using CyberKnife.

Methods: We extracted the list and data of 39 patients with clinically localized prostate cancer who had undergone primary SBRT using CyberKnife between January 2008 and December 2012 from the Smart Prostate Cancer database system of Seoul St. Mary's Hospital. Changes in PSA over time, PSA velocity, and PSA nadir were evaluated from the completion of SBRT using CyberKnife. Biochemical recurrence (BCR)-free survival after primary SBRT using CyberKnife was determined using Kaplan-Meier analysis.

Results: The rate of PSA decrease was maximal in the first month (median -3.34 ng/mL/mo), which then fell gradually with median values of -1.51, -0.32, -0.28, -0.20, and -0.03 ng/mL/mo for durations of 3, 6, 9, 12, and 24 months after SBRT using CyberKnife, respectively. The median PSA nadir was 0.31 ng/mL after a median 23 months. Kaplan-Meier analysis calculates an actuarial 5-year BCR-free survival after SBRT using CyberKnife as 80.8%.

Conclusions: PSA decline occurred rapidly in the first month, and then the rate of PSA decline fell off steadily over time throughout 2 years after treatment. Also, SBRT using CyberKnife leads to long-term favorable BCR-free survival in localized prostate cancer.

Keywords: Localized prostate cancer; PSA kinetics; Stereotactic body radiation therapy.