Osteonecrosis of the jaw (ONJ) in androgen-independent prostate cancer (AIPC) patients receiving ATTP (bevacizumab, docetaxel, thalidomide, and prednisone)

Abstract

19594 Background: ONJ has been associated with IV bisphosphonate use in cancer patients (pts) and chemotherapy may be an additional risk factor. ONJ is believed to result from localized vascular insufficiency due to faulty bone remodeling. ONJ incidence in pts not receiving chemotherapy (e.g. Paget's disease) is reportedly only 0.8%; prostate cancer pts have an incidence of 6.5%. Methods: We reviewed data from pts with advanced AIPC who developed ONJ while being treated on a Phase II study of ATTP. Results: Six of 36 (17%) pts treated with ATTP had ONJ confirmed by oral surgery. Four of the 6 pts presented with pain and, in five, the ONJ was mandibular in location. All pts were treated conservatively with either sequestrectomy or oral cleansing with chlorhexidine. All pts had been treated monthly with IV zoledronic acid (ZA). The mean duration of ZA use before diagnosis of ONJ was 20 months (mos). One patient had been treated with oral alendronate for 3 years and then developed ONJ after 5 mos of ZA. Of the 36 pts on-study, previous dental history could be verified in 24 pts. ONJ was diagnosed in 4 of the 5 pts with a prior dental infection or invasive dental procedure. Pts received an average of 11 cycles of ATTP before ONJ was diagnosed. All pts with ONJ had received full doses of bevacizumab and most had received full doses of all medications for all cycles. Conclusions: The possibility exists that the risk for ONJ may be higher with specific chemotherapy regimens, particularly those that include steroids or anti-angiogenic agents. However, at this time prior dental infections or procedures remain the greatest known risk factor. It is also possible that the relatively high incidence of ONJ in prostate cancer patients may reflect increased awareness in this population. Randomized phase III trials in AIPC, specifically addressing the incidence of ONJ, are needed to determine whether specific chemotherapy regimens are associated with an increased risk of this complication. No significant financial relationships to disclose.