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Letter to the Editor

Bisphosphonate Safety and Tolerability

Department of Internal Medicine, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium

Correspondence: Jean-Jacques Body, M.D., Ph.D., Department of Internal Medicine, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium. Telephone: 32-2-541-3303; Fax: 32-2-541-3310; e-mail: jj.body{at}bordet.be

The article by Conte and Guarneri raises several important points about the safety and tolerability of bisphosphonates [1]. After discussing the benefits and limitations of oral and intravenous methods of administration, the authors conclude that i.v. bisphosphonates should be the treatment of choice in patients with malignant bone disease. Due to concern of patient mismanagement, I alert you to the fact that the article contains a number of inaccurate statements.

First, Conte and Guarneri misinterpret gastrointestinal (GI) safety data for oral ibandronate. The incidence of GI adverse events is reported as 14.6% for ibandronate patients and 7.6% for placebo patients. Readers should know that this incorrectly assumes that each GI event occurred in separate patients. In fact, the article by Body et al. reports the number of patients with GI effects to be similar between the ibandronate and placebo groups [2].

The authors also imply that, in the oral trials, 10% of patients receiving oral ibandronate withdrew due to GI adverse events. To the contrary, withdrawal in the trials was for any adverse event regardless of whether the event was linked to ibandronate therapy [2]. Furthermore, none of the patients on oral ibandronate discontinued or were noncompliant due to GI toxicity.

Conte and Guarneri suggest that the clinical benefit of oral ibandronate is limited by the treatment regimen and GI toxicity. The authors are correct in pointing out that the size and number of clodronate tablets can greatly compromise patient acceptability. However, this is untrue for oral ibandronate, which is given once daily and has a much smaller tablet than that of clodronate (about 1 cm in length). High doses are not required for oral ibandronate, and tablet size and quantity are not issues. It is also noteworthy that the product labeling for oral ibandronate states that "fasting should be continued for at least 30 minutes after taking the tablet" [3] and not the 1-hour fast reported by Conte and Guarneri. Moreover, the labeling does not state that the patient must remain upright.

Another limitation of the article is the use of osteoporosis data to suggest possible shortcomings of oral bisphosphonate therapy. Such comparisons are inconclusive, since patients with osteoporosis are distinctly different from those with metastatic bone disease.

Inaccurate interpretation of data can ultimately influence practice changes, potentially jeopardizing patient outcomes. As oncologists, it is vital that we assess the available literature thoroughly and use good clinical judgment to manage our patients in their best interest.

	DISCLOSURE OF POTENTIAL CONFLICTS OF INTEREST

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Dr. Body acted as a consultant for Roche and Amgen and has performed contract work for Roche, Amgen, and Novartis.

	REFERENCES

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1. Conte P, Guarneri V. Safety of intravenous and oral bisphosphonates and compliance with dosing regimens. The Oncologist 2004;9(suppl 4):28–37.[Abstract/Free Full Text]
2. Body JJ, Diel IJ, Lichinitzer M et al. Oral ibandronate reduces the risk of skeletal complications in breast cancer patients with metastatic bone disease: results from two randomised, placebo-controlled phase III studies. Br J Cancer 2004;90:1133–1137.[CrossRef][Medline]
3. Oral Bondronat (ibandronate). Summary of Product Characteristics. Basel, Switzerland: F. Hoffmann-La Roche Ltd, 2003.

This article has been cited by other articles:

				M. Botteman, V. Barghout, J. Stephens, J. Hay, J. Brandman, and M. Aapro Cost effectiveness of bisphosphonates in the management of breast cancer patients with bone metastases Ann. Onc., July 1, 2006; 17(7): 1072 - 1082. [Abstract] [Full Text] [PDF]

				B. A. Chabner Late Toxicities of Drugs: Bisphosphonates Oncologist, May 1, 2005; 10(5): 301 - 303. [Full Text] [PDF]

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