We conducted a randomized , double-blind , placebo-controlled , multinational study of the somatostatin analogue lanreotide in patients with advanced , well-differentiated or moderately differentiated , nonfunctioning , somatostatin receptor-positive neuroendocrine tumors of grade @ or @ ( a tumor proliferation index -LSB- on staining for the Ki-@ antigen -RSB- of < @ % ) and documented disease-progression status .