Pamidronate Administration in Breast Cancer Patients With Bone Metastases

Background: Pamidronate (PMT) is effective in reducing skeletal related events (SRE) in breast cancer (BC) patients with bone metastasis (BM). Its best way of administration and optimum treatment duration are still to be determined. Objective: evaluate the efficacy of continuous administration (arm A) vs. alternate administration (arm B) of PMT to delay time to first SRE in BC pt presenting with symptomatic BM. Methods: patients aged \>18, Eastern Cooperative Oncology Group (ECOG) performance status ≥ 2, adequate renal function, and BC symptomatic BM were eligible. BM was defined as presence of 3 or more hot spots (HS) in skeletal scintigraphy (SS), or any number of HS in SS if osteolytic, osteoblastic or mixed bone lesions determined by radiography, or 2 or less HS in SS if magnetic resonance or CT scan confirmation of BM. Symptomatic BM was defined as pain associated to SS HS, or SRE (pathological fractures or spine cord compression or radiation bone treatment or tumour induced hypercalcemia), or treatment with analgesia due to bone pain. Patients were allowed up to 1 previous chemotherapy and 2 previous hormone therapy lines for metastatic disease. Antineoplastic therapy could be changed at any time during the study. Eligible patients were stratified (isolated bone metastasis or associated to node or skin lesions vs. bone metastasis associated to visceral disease) and randomized to receive 2 hour-iv. PMT 90 mg every 3-4 weeks for 18 months (arm A) or iv. PMT 90 mg every 3-4 weeks for 6 months, followed by a 6 months rest, and a new 6 months on-treatment period (arm B). Quality of Life (QoL) was measured with short form (SF)-36 questionnaire.