Osteonecrosis of the jaw (ONJ) risk in breast cancer patients after zoledronic acid treatment.

We have read with interest the paper by T. Fehm. et al.1 published on August number of The Breast. We agree with recommendations for prevention of bisphosphonate-associated osteonecrosis of the jaw (ONJ) appointed by the multidisciplinary task force of the German society of senology, that lengthens the list of recommendations established worldwide by authorities and scientific societies to minimize the risk of ONJ in cancer patients. However, we do not agree with one assertion in the risk factors chapter. About the type of bisphosphonate, the authors state that “in the absence of head to head studies investigating the risk for ONJ with different bisphosphonates (…), no definitive answer can be given”. At our knowledge, several data are strongly suggestive for a higher ONJ risk for patients treated with zoledronic acid (the most potent compound of this drug class) in comparison with those receiving pamidronate, whereas no enough data are available for ibandronate, a less frequently used bisphosphonate