Analysis of Frequency and Risk Factors for Developing Bisphosphonate Associated Osteonecrosis of the Jaw.

Although the evidence available associating bisphosphonates (BP) with osteonecrosis of the jaw (ONJ) is far from conclusive, the growing literature reports strongly suggest a strict relationship between them. The real frequency of this complication is unknown because of the recent observation of this condition, the bias related to retrospective studies and the wide-spread use of this supportive therapy.

Aims of this research were to look for additional risk factors for developing ONJ and to determine the frequency of this event in the subgroup of patients affected by Multiple Myeloma (MM) treated with BP.

We asked 49 GISL centers to participate in a retrospective multicenter study filling out a form containing several queries, including sex and age, anamnesis for smoke habit, anemia and thrombotic events, type and time of neoplasia diagnosis, treatment and neoplasia status, odonthoiatric anamnesis, type and duration of therapy with BP, microbial isolation in site of lesion, specific treatment for osteonecrosis, number of patients (pts) affected by MM treated with BP from 2002 to 2005. Fifteen centers decided to participate in the study and 12 had cases of osteonecrosis.

ONJ was reported in 19 pts. Sixty % were females and the median age was 65 ys. Sixteen had MM, 1 breast cancer, 1 prostatic cancer, 1 osteoporosis steroid related. Median time from diagnosis of cancer was 54 months and median duration of treatment with BP was 34 months. Thirteen events manifested between 20 and 60 months. Of the 19 pts, 8 had received zolendronate, 2 pamidronate and 9 both drugs. None had radiotherapy on head and neck, while two received total body irradiation. In these two cases, ONJ was associated with necrosis of the pelvis. The 2 solid tumors were treated with ormonal therapy.

All MM pts had received one or more line of treatment including, VAD, MP, steroids and thalidomide alone or in combination, as well as high dose melphalan, as part of autologous bone marrow transplant.

ONJ involved the mandible in 14 pts, the maxilla in 3 and both in 2. Symptoms included local pain and discomfort. In 17 cases CT scan was the strumental procedure used to identifiy the lesion. In 14 pts biopsy was performed excluding localization of neoplasia in 11 cases. Microbiological evaluation of the lesion was positive in 11 pts, with 6 cases of Actynomices. In 12 patients ONJ was apparently spontaneous; in 7 occurred after dental procedures. Parodonthopaties were present in 10 pts. In 11 cases ONJ was complicated by fistula, exposed bone or abscess. BP were stopped in 17 pts. Antibiothic therapy was administered in 17 cases; 7 pts underwent hyperbaric oxygen therapy and 8 surgical debridement. Several pts improved but none were cured.

Considering only the MM subgroup 16 cases of ONJ were identified among 888 pts treated with BP between 2002 and 2005, with a frequency of 1.8%.

Utilizing the data collected by our retrospective study a fine statistical analysis is not applicable. However, in MM pts the frequency of steroid treatment, parodonthopaties and anemia was particularly high, respectively 100%, 56%, and 56%, supporting the idea that these are additional risk factors for developing ONJ.