Inhibition of tumor cell kinetics and serum insulin growth factor I levels by octreotide in colorectal cancer patients.

Abstract

Octreotide was shown to inhibit the growth of colon cancer and to reduce serum concentrations of tumor growth factors such as insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) in vitro and in animal models. Effects of octreotide on tumor cell kinetics and serum concentration of IGF-I and EGF in patients with colorectal cancer were evaluated. Seventy-five patients with colorectal cancer were randomized to receive octreotide (200 micrograms daily) in the 2 weeks before surgery or the usual medications. Samples of tumor tissue were taken at endoscopy and at surgery. [3H]Thymidine labeling index and flow cytometry were used to assess the S-phase fraction. In octreotide-treated patients, plasma levels of IGF-I, EGF, and growth hormone were assessed before and after treatment. There was a statistically significant reduction in the mean percentage of the S-phase fraction as a result of octreotide treatment measured by both [3H]thymidine labeling index (P = 0.001) and flow cytometry (P = 0.001). No reduction in the percentage of the S-phase fraction was observed in the control group patients. Serum values of IGF-I were significantly reduced by octreotide, whereas EGF and growth hormone levels were not affected. Octreotide reduces the proliferative activity of tumor cells and the serum IGF-I levels in patients with colorectal cancer. This activity may have a role in the treatment of colorectal cancer.