Pamidronate Administration in Breast Cancer Patients With Bone Metastases

Randomized, Multicentric Phase IV Clinical Trial for the Administration of Pamidronate in Breast Cancer Patients With Bone Metastases

The study objective is to evaluate the differences, in terms of first occurrence of a skeletal event, in patients with breast cancer and symptomatic bone metastases, when pamidronate is administered during 2 years, or when it is administered during 6 months, followed by a six month rest period, and again a 6 month treatment period.

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.

Inclusion Criteria:

• Written informed consent.
• Up to two previous or current hormone therapy treatments for metastatic breast cancer are allowed.
• Normal or borderline renal function (serum creatinine < 1.5 x upper normal limit [UNL]).
• Normal calcium levels in serum, or slightly non-symptomatic high levels (< 1.25 x UNL).
• Performance status 0, I or II in World Health Organization (WHO) scale.

Exclusion Criteria:

• Treatment with bisphosphonates in the 30 previous days, or any time if the indication was treatment of metastatic bone lesions.
• Treatment with bisphosphonates is only allowed if the indication is hypercalcaemia.
• Metastases in central nervous system (CNS).
• Hypersensitivity to bisphosphonates or other components of the formula.
• Pregnant or lactating women.
• Previous or current treatment with a second chemotherapy line or a third hormone therapy line for metastatic disease.