Reduction of Skeletal Morbidity and Prevention of Bone Metastases with Oral Clodronate in Women with Recurrent Breast Cancer in the Absence of Skeletal Metastases

The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 21, 1996

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A.H.G. Paterson, MD, head, Division of Medical Oncology, Department of Medicine, University of Calgary (Alberta, Canada), presented the results of a study which examined the effect of clodronate on the incidence of skeletal metastases and skeletal morbidity in women with recurrent breast cancer.

Bone is a frequent site for recurrent breast cancer to develop. The spread of breast cancer to bone can cause a great deal of suffering, with destrction of the bone leading to pain, fracture, and high levels of calcium in the blood, which makes patients sick.

Clodronate is a bisphosphonate, a substance that inhibits the destruction of bone by interfering with the function of bone cells called osteoclasts, which destroy bone. Initially, bisphonosphonates were shown to be beneficial in patients with high levels of calcium in the blood. More recently, bisphosphonates have been demonstrated to be beneficial in reducing the morbidity and suffering related to bone metastases.

In this double-blind trial of 133 women, 66 patients were randomized to receive clodronate and 67 received a placebo. Fewer patients developed skeletal metastases during clodronate treatment than during placebo (15 patients versus 19) and the total number of skeletal metastases was significantly lower (32 versus 63). In addition, there were fewer hypercalcemia incidents among patients taking clodronate versus placebo (10 patients versus 17).

The study results suggest that bisphosphonates, while not killing cancer cells or affecting their growth directly, may be helpful in influencing the appearance of metastases in bone.

"This study is one of the first to suggest that by influencing the 'soil,' the 'seed' of cancer cell growth can be affected," said Patricia Braly, MD, professor and chief, Department of Obstetrics and Gynecology, LSA Medical Center (New Orleans, LA), at a press briefing.

The study results were encouraging enough to initiate a trial of oral clodronate in reducing the rate of future recurrences in bone for patients with operable breast cancer.