title: VMAT technique enables concomitant radiotherapy of prostate cancer and pelvic bone metastases.
abstract: BACKGROUND
  Prostate cancer (PCa) patients with metastatic disease often suffer from skeletal pain and urinary retention impairing their quality of life. Prophylactic radiotherapy to bone metastases planned concomitantly with primary PCa radiotherapy could enable more precise control of combined dose in healthy tissues when compared to sequential palliative treatment.
  
  
  METHODS
  Volumetric modulated arc therapy (VMAT) was planned for 14 PCa patients with primary bone metastases. The bone planning target volume (PTVbone) was contoured together with the PTVs of prostate (pr), pelvic lymph nodes (ln) and seminal vesicles (sv). Another virtual plan was calculated excluding PTVbone for dose volume histogram (DVH) comparison. DVHs were additionally compared to a set of actual VMAT treatment plans of a control cohort of 13 high risk PCa patients treated with PTVpr, PTVsv and PTVln. The prescribed doses varied between 42 and 76 Gy for PTVbone.
  
  
  RESULTS
  Recommended healthy tissue tolerances (Quantec) were not exceeded except for one patient's rectum V50Gy value. Rectum doses did not increase significantly due to the inclusion of PTVbone. For bladder, there was a slight increase for V65Gy and V50Gy (2.7% and 7.4%). The DVHs of metastatic and non-metastatic patients were comparable. There were no differences in the PTVpr DVH parameters, while mean PTVln dose increased by 3.7 Gy-4.4 Gy due to the increased treatment volume related to PTVbone. All side effects were <grade 3 during the mean follow-up duration of 25 months.
  
  
  CONCLUSIONS
  VMAT offers a good optimization tool for adding extra PTVs to the radiotherapy plan. Radiotherapy of bone metastases concomitantly with irradiation of the primary prostate tumor is a safe and well-tolerated approach and deserves to be studied in a randomized setting.
authors.affiliation: Docrates Cancer Center , Helsinki , Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Kiljunen
authors.forename: Aki
authors.initials: A
authors.lastname: Kangasmäki
authors.forename: Aili
authors.initials: A
authors.lastname: Aaltonen
authors.forename: Kalevi
authors.initials: K
authors.lastname: Kairemo
authors.forename: Kaarina
authors.initials: K
authors.lastname: Partanen
authors.forename: Greetta
authors.initials: G
authors.lastname: Joensuu
authors.forename: Tuomo
authors.initials: T
authors.lastname: Alanko
authors.forename: Leila
authors.initials: L
authors.lastname: Vaalavirta
authors.forename: Timo
authors.initials: T
authors.lastname: Joensuu
mesh_terms: D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects; D010384:Pelvic Bones; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum / Q000528:radiation effects; D012189:Retrospective Studies; D013997:Time Factors