AUTHOR=Laughlin Brady S. , Silva Alvin C. , Vora Sujay A. , Keole Sameer R. , Wong William W. , Schild Michael H. , Schild Steven E. 

TITLE=Long-term outcomes of prostate intensity-modulated radiation therapy incorporating a simultaneous intra-prostatic MRI-directed boost

JOURNAL=Frontiers in Oncology

VOLUME=Volume 12 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2022.921465

DOI=10.3389/fonc.2022.921465

ISSN=2234-943X

ABSTRACT=Purpose/Objectives: This retrospective study demonstrates the long-term outcomes of treating prostate cancer using intensity modulated (IMRT) with incorporation of MRI directed boost. 
Materials/Methods: From February 2009 to February 2013, 78 men received image guided IMRT delivering 77.4 Gy in 44 fractions with simultaneously integrated boost to 81-83 Gy to an MRI identified lesion. Patients with intermediate risk or high-risk prostate cancer were recommended to receive 6 months and 24-36 months of adjuvant hormonal therapy, respectively.
Results: Median follow-up was 113 months (11 – 147). There were 18 low risk, 43 intermediate risk, and 17 high risk patients per NCCN risk stratification included in this study. Adjuvant hormonal therapy was utilized in 32 patients (41%). The 10-year biochemical control rate for all patients was 77%. The 10-year biochemical control rates for low risk, intermediate risk and high-risk diseases were 94%, 81%, and 88%, respectively (p=0.35). The 10-year rates of local control, distant control and survival were 99%, 88%, and 66%, respectively. Of 25 patients who died, only 4 (5%) died of prostate cancer. On univariate analysis, T-category and pre-treatment PSA level were associated with distant failure rate (p = 0.02).  There was no Grade >3 genitourinary and gastrointestinal toxicities that persisted at last follow-up. 
Conclusions: This study demonstrated the long-term efficacy of using MRI to define an intra-prostatic lesion for SIB to 81- 83Gy while treating the entire prostate gland to 77.4Gy with IMRT. Our study confirms that modern MRI can be used to locally intensify dose to prostate tumors providing high long-term disease control while maintaining favorable long-term toxicity.