A tumor-associated marker protein was purified and antibodies thereto developed for cancer diagnosis and assessment of cancer risk associated with the long-term use of synthetic steroid hormones, both contraceptive and non-contraceptive, and other drugs that exhibit tumor promotional properties. The marker protein and antibodies thereto provided are interspecies immunologically cross-reactive. In summary, the marker p65 tumor-associated factor of the present invention has the following characteristics: PA1 (a) binds substantially completely to a phenyl hydrophobic interaction column in a buffer containing 20% ammonium sulfate and eluted at ca. 16% ammonium sulfate; PA1 (b) localized primarily in the nuclear envelopes with only small amounts present in the cytoplasm from where is released to the blood circulation in vivo or cell culture medium in vitro; PA1 (c) induced in normal, adult tissues by chemical carcinogens (initiators) but not by tumor promoters, the carcinogen-induced production being enhanced by the latter. Also disclosed herein are processes for purifying the 65 kDa tumor marker from plasma, tumor cytosol or ascitic fluid of carcinoma bearing animals; processes for producing antisera and purified antibody preparations to the 65 kDa tumor marker; and methods using antibody to the 65 kDa to diagnose or assess the likelihood of cancer.Board of Regents, University of Texas Syste
