In an effort to explore the use of polypeptide growth factors as potential markers for cancer detection, we have identified the presence of transforming growth factor-alpha (TGF-alpha) in pooled urine of patients with metastatic breast cancer by a commercial radioimmunoassay (RIA) based on a rabbit antiserum raised to the C-terminal 17aa synthetic fragment of rat TGF-alpha. This TGF-alpha RIA detected both high molecular weight (HMW) and low molecular weight (LMW) forms of TGF-alpha in the conditioned media of a breast cancer cell line (MDA-MB-231) and in the urine of healthy women and those with breast cancer. The ratio of HMW to LMW species of TGF-alpha by RIA after Bio-Gel P-100 chromatography was approximately equal in pooled urine samples from both healthy women and those with breast cancer, and in the conditioned media from the cell line MDA-MB-231. Using established procedures for concentrating urinary proteins from 24-h urine samples by adsorption onto methyl-bonded microparticulate silica and selective elution by acetonitrile, TGF-alpha RIA results from women with disseminated breast carcinoma were compared with those of healthy pre- and post-menopausal control women. Analysis indicated a median TGF-alpha value of 981 ng/g urinary creatinine for urine samples from cancer patients (range 608 to 1737) and 642 ng/g creatinine (range 417 to 941) for control urine samples. Although the difference was statistically significant (p less than 0.05), urinary TGF-alpha detection with this assay method appears to have limited usefulness as a diagnostic marker for metastatic human adenocarcinoma of the breast.(ABSTRACT TRUNCATED AT 250 WORDS)