van Geene P, Kehoe S, Luesley D, Ward K. Growth promoting properties of cell free malignant ascites and benign peritoneal fluid on epithelial ovarian carcinoma cells in culture. Int J Gynecol Cancer 1998; 8: 197–202. The growth of epithelial ovarian carcinoma is regulated by a number of cytokines, some of which are stimulatory and some inhibitory. The cells of origin of these cytokines are known in only a few cases but include tumor cells, lymphocytes, macrophages, other components of the immune system, and mesothelial cells. Malignant ascites and non‐malignant peritoneal fluid contain varying quantities of cytokines dependent on the cell populations present and therefore the relative importance of any individual cytokine in the stimulation of tumor cells may vary between patients. Because of the potential for cytokines to act in synergy or in short paracrine loops it is proposed that the overall growth regulating effect of ascites is of clinical importance to the patient with ovarian carcinoma. We have measured the overall stimulatory effect of 38 malignant and 26 benign, cell free, peritoneal fluids on the growth of epithelial ovarian carcinoma cells cultured in vitro. In all cases, peritoneal fluid increased the growth of ovarian carcinoma cells in vitro when compared to standard growth media. There was no significant difference in stimulation between peritoneal fluid obtained from benign ovarian tumors and other benign gynecologic conditions, but fluid obtained from patients with ovarian carcinoma had a significantly greater growth stimulatory effect (P = 0.0132).