Simultaneous integrated boost with stereotactic radiotherapy for dominant intraprostatic lesion of localized prostate cancer: a dosimetric planning study

Yeon Joo Kim,Kyoung Jun Yoon,Young Seok Kim

doi:10.1038/s41598-020-71715-2

Yeon Joo Kim, Kyoung Jun Yoon + Show 1 more

Open Access

https://doi.org/10.1038/s41598-020-71715-2

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Journal: Scientific Reports	Publication Date: Sep 7, 2020
Citations: 5	License type: open-access

Affiliation: Asan Medical Center, University of Ulsan

Abstract

Dominant intraprostatic lesion (DIL) has been known as the most common local recurrence site of prostate cancer. We evaluated the feasibility of simultaneous integrated boost (SIB) to DIL with CyberKnife stereotactic body radiotherapy (CK-SBRT). We selected 15 patients with prostate cancer and visible DIL and compared 3 plans for each patient: 1) No boost plan of 35 Gy to prostate, 2) DIL_40 plan of SIB 40 Gy to DIL and 35 Gy to prostate, and 3) DIL_45 plan with 45 Gy to DIL and 35 Gy to the prostate in 5 fractions. All targets satisfied with the prescription coverage per protocol. However, some patients failed to meet the Dmax of the rectum in DIL_40 plans (n = 4), and DIL_45 plans (n = 6). Violations of bladder constraints occurred in four DIL_45 plans. Consequently, the DIL boost with SBRT was possible in 73% of patients with DIL_40 plans, and 60% of patients with DIL_45 plans without any violation of normal organ constraints. All patients who experienced constraint violations had DILs in posterior segments. DIL boost using CK-SBRT could be an option for localized prostate cancer patients. For patients who had DIL in posterior segments, a moderate dose escalation of 40 Gy seemed appropriate.

Highlights

Dominant intraprostatic lesion (DIL) has been known as the most common local recurrence site of prostate cancer
Four patients presented with Gleason score (GS) 6, 10 patients had GS 7, and one patient diagnosed with GS 9
All patients who resulted in organs at risk (OAR) constraint violations had posterior segment dominant intraprostatic lesion (DIL)

Summary

Introduction

Dominant intraprostatic lesion (DIL) has been known as the most common local recurrence site of prostate cancer. We evaluated the feasibility of simultaneous integrated boost (SIB) to DIL with CyberKnife stereotactic body radiotherapy (CK-SBRT). DIL boost using CK-SBRT could be an option for localized prostate cancer patients. A higher dose to the entire prostate is limited by adjacent normal tissue tolerance, and there were studies that the most common local recurrence site of prostate cancer following conventional fractionated EBRT was the dominant intraprostatic lesion (DIL)[3,4]. We tried to find the appropriate dose prescription satisfying both target coverage and organs at risk (OAR) constraints and to demonstrate for which patient violation of normal organ constraints would occur (Table 1)

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Conclusion