Treatment of metastatic breast cancer with somatostatin analogues--a meta-analysis

Somatostatin analogues appear to have antiproliferative effects in breast cancer by inhibiting various hormones. Several small phase 1 and 2 clinical trails have evaluated the efficacy of somatostatin analogues, but the results are varied. The purpose of this study was to use the technique of meta-analysis to determine the effect of somatostatin analogues on tumor response, toxicity, and serum hormone levels in women with metastatic breast cancer. All published and unpublished trials were reviewed. Meta-analysis was preformed by best linear unbiased estimate regression with observations weighted inversely to their variance. Significance was considered at P < .05. Fourteen studies (N = 210) were included. Positive tumor response was reported in 87 patients (41.4%). Mean duration of response was 3.9 months. Response was best when somatostatin analogues were given as first-line therapy (69.5% versus 28.5%, P < .006) and in patients with < or =2 metastases (45.0% versus 5.6%, P = .3). Mild side effects occurred in 47 of 185 patients (25.4%). Therapy was associated with a decrease in serum insulin-like growth factor (IGF-1) and an increase in growth hormone. In patients with metastatic breast cancer, treatment with somatostatin analogues was associated with a tumor response of over 40% with few side effects. Best results were achieved when somatostatin analogues were given as first-line therapy.