title: Late toxicity and biochemical control in 554 prostate cancer patients treated with and without dose escalated image guided radiotherapy.
abstract: OBJECTIVE
  To compare rates of late gastrointestinal toxicity, late genitourinary toxicity and biochemical failure between patients treated for prostate cancer with implanted fiducial marker image guided radiotherapy (FMIGRT), and those treated without FMIGRT.
  
  
  METHODS
  We performed a single institution retrospective study comparing all 311 patients who received 74 Gy without fiducial markers in 2006 versus all 243 patients who received our updated regimen of 78 Gy with FMIGRT in 2008. Patient records were reviewed 27 months after completing radiotherapy. Biochemical failure was defined using the Phoenix definition. Details of late gastrointestinal and genitourinary toxicities were graded according to CTCAEv4. Moderate/severe toxicity was defined as a grade 2 or higher toxicity. Cumulative incidence and prevalence curves for moderate/severe toxicity were constructed and compared using multistate modeling while biochemical failure free survival was compared using the log rank test. A Cox regression model was developed to correct for confounding factors.
  
  
  RESULTS
  Median follow-up time for both groups was 22 months. The hazard ratio for moderate/severe late gastrointestinal toxicity in the non-FMIGRT group was 3.66 [95% CI (1.63-8.23), p=0.003] compared to patients in the FMIGRT group. There was no difference in the hazard ratio of moderate/severe late genitourinary toxicity between the two groups (0.44 [95% CI (0.19-1.00)]), but patients treated with FMIGRT did have a quicker recovery from their genitourinary toxicities HR=0.24 [95% CI (0.10-0.59)]. We were unable to detect any differences in biochemical failure free survival between the cohorts HR=0.60 [95% CI (0.30-1.20), p=0.143].
  
  
  CONCLUSIONS
  Despite dose escalation, the use of FMIGRT in radical radiotherapy for prostate cancer significantly reduces the incidence of gastrointestinal toxicity and the duration of late genitourinary toxicity when compared to conventional non-FMIGRT techniques.
authors.affiliation: Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia. david.kok@petermac.org
authors.forename: David
authors.initials: D
authors.lastname: Kok
authors.forename: Suki
authors.initials: S
authors.lastname: Gill
authors.forename: Mathias
authors.initials: M
authors.lastname: Bressel
authors.forename: Keelan
authors.initials: K
authors.lastname: Byrne
authors.forename: Tomas
authors.initials: T
authors.lastname: Kron
authors.forename: Chris
authors.initials: C
authors.lastname: Fox
authors.forename: Gillian
authors.initials: G
authors.lastname: Duchesne
authors.forename: Keen Hun
authors.initials: KH
authors.lastname: Tai
authors.forename: Farshad
authors.initials: F
authors.lastname: Foroudi
mesh_terms: D006801:Humans; D008297:Male; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D061089:Radiotherapy, Image-Guided / Q000009:adverse effects; D012189:Retrospective Studies