title: Outcomes of hypofractionated stereotactic body radiotherapy boost for intermediate and high-risk prostate cancer.
abstract: OBJECTIVE
  Treatment of intermediate and high-risk prostate cancer with a high BED has been shown to increase recurrence free survival (RFS). While high dose rate (HDR) brachytherapy, given as a boost is effective in delivering a high BED, many patients are not candidates for the procedure or wish to avoid an invasive procedure. We evaluated the use of stereotactic body radiotherapy (SBRT) as a boost, with dosimetry modeled after HDR-boost.
  
  
  METHODS
  Fifty patients were treated with two fractions of SBRT (9.5-10.5 Gy/fraction) after 45 Gy external-beam radiotherapy, with 48 eligible for analysis at a median follow-up of 42.7 months.
  
  
  RESULTS
  The Kaplan-Meier estimates of biochemical control post-radiation therapy (95 % Confidence Interval) at 3, 4 and 5 years were 95 % (81-99 %), 90 % (72-97 %) and 90 % (72-97 %), respectively (not counting 2 patients with a PSA bounce as failures). RFS (defined as disease recurrence or death) estimates at 3, 4 and 5 years were 92 % (77-97 %), 88 % (69-95 %) and 83 % (62-93 %) if patients with PSA bounces are not counted as failures, and were 90 % (75-96 %), 85 % (67-94 %) and 75 % (53-88 %) if they were. The median time to PSA nadir was 26.2 months (range 5.8-82.9 months), with a median PSA nadir of 0.05 ng/mL (range <0.01-1.99 ng/mL). 2 patients had a "benign PSA bounce", and 4 patients recurred with radiographic evidence of recurrence beyond the RT fields. Treatment was well tolerated with no acute G3 or higher GI or GU toxicity and only a single G3 late GU toxicity of urinary obstruction.
  
  
  CONCLUSIONS
  SBRT boost is well-tolerated for intermediate and high-risk prostate cancer patients with good biochemical outcomes and low toxicity.
authors.affiliation: Department of Radiation Oncology, University of California San Francisco, 1825 4th Street, San Francisco, CA, 94158, USA. mekhail.anwar@ucsf.edu.
authors.forename: Mekhail
authors.initials: M
authors.lastname: Anwar
authors.affiliation: Department of Radiation Oncology, University of California San Francisco, 1600 Divisadero St. Suite H1031, San Francisco, CA, 94143-1708, USA. vivian_weinberg@yahoo.com.
authors.forename: Vivian
authors.initials: V
authors.lastname: Weinberg
authors.affiliation: Department of Radiation Oncology, Beaumont Health, 44201 Dequindre Rd, Troy, MI, 48085, USA. seymoza@gmail.com.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Seymour
authors.affiliation: Department of Radiation Oncology, University of California San Francisco, 1600 Divisadero St. Suite H1031, San Francisco, CA, 94143-1708, USA. ichow.Hsu@ucsf.edu.
authors.forename: I Joe
authors.initials: IJ
authors.lastname: Hsu
authors.affiliation: Department of Radiation Oncology and Urology, University of California San Francisco, 1600 Divisadero St. Suite H1031, San Francisco, CA, 94143-1708, USA. mack.roach@ucsf.edu.
authors.forename: Mack
authors.initials: M
authors.lastname: Roach
authors.affiliation: Department of Radiation Oncology, University of California San Francisco, 1600 Divisadero St. Suite H1031, San Francisco, CA, 94143-1708, USA. alexander.gottschalk@ucsf.edu.
authors.forename: Alex R
authors.initials: AR
authors.lastname: Gottschalk
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001918:Brachytherapy / Q000379:methods; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry / Q000379:methods; D016634:Radiosurgery / Q000379:methods*; D012306:Risk; D016896:Treatment Outcome
chemical_list: D017430:Prostate-Specific Antigen