title: Avascular Necrosis of the Femoral Head After Palliative Radiotherapy in Metastatic Prostate Cancer: Absence of a Dose Threshold?
abstract: Avascular necrosis (AVN) is the final common pathway resulting from insufficient blood supply to bone, commonly the femoral head. There are many postulated etiologies of non-traumatic AVN, including corticosteroids, bisphosphonates, and radiotherapy (RT). However, it is unclear whether there is a dose threshold for the development of RT-induced AVN. In this case report, we describe a patient with prostate cancer metastatic to bone diagnosed with AVN after receiving single-fraction palliative RT to the left femoral head. Potential contributing factors are discussed, along with a review of other reported cases. At present, the RT dose threshold below which there is no risk for AVN is unknown, and therefore detrimental impact from the RT cannot be excluded. Given the possibility that RT-induced AVN is a stochastic effect, it is important to be aware of the possibility of this diagnosis in any patient with a painful hip who has received RT to the femoral head.
authors.affiliation: Faculty of Medicine, Cross Cancer Institute, University of Alberta.
authors.forename: Alia M
authors.initials: AM
authors.lastname: Daoud
authors.affiliation: Oncologic Imaging, Cross Cancer Institute, University of Alberta.
authors.forename: Mack
authors.initials: M
authors.lastname: Hudson
authors.affiliation: Oncologic Imaging, Cross Cancer Institute, University of Alberta.
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Magnus
authors.affiliation: Radiation Oncology, Cross Cancer Institute, University of Alberta.
authors.forename: Fleur
authors.initials: F
authors.lastname: Huang
authors.affiliation: Department of Oncology, Cross Cancer Institute, University of Alberta.
authors.forename: Brita L
authors.initials: BL
authors.lastname: Danielson
authors.affiliation: Medical Oncology, Cross Cancer Institute, University of Alberta.
authors.forename: Peter
authors.initials: P
authors.lastname: Venner
authors.affiliation: Medical Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre.
authors.forename: Ronak
authors.initials: R
authors.lastname: Saluja
authors.affiliation: Palliative Radiation Oncology, Cross Cancer Institute, University of Alberta.
authors.forename: Bronwen
authors.initials: B
authors.lastname: LeGuerrier
authors.affiliation: Radiation Therapy, Cross Cancer Institute, University of Alberta.
authors.forename: Helene
authors.initials: H
authors.lastname: Daly
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre.
authors.forename: Urban
authors.initials: U
authors.lastname: Emmenegger
authors.affiliation: Radiation Oncology, Cross Cancer Institute, University of Alberta.
authors.forename: Alysa
authors.initials: A
authors.lastname: Fairchild
keywords: avascular necrosis; palliative radiotherapy; stochastic effect