Enzyme immunoassay for placental protein 4 (PP4) and its possible diagnostic significance in patients with genital tract cancer.

We have established an enzyme immunoassay for placental protein 4 (PP4), by using avidin-biotin binding reaction, and set its normal range below 10.9 ng/ml (mean + 2 sigma). Throughout the menstrual cycle, the serum PP4 profile was similar to that of serum progesterone. In the follicular and ovulatory phase, PP4 remained relatively low, with the mean levels of 1.5 ng/ml and 1.8 ng/ml, respectively. In the luteal phase, the mean level was 3.2 ng/ml. In normal pregnancy, serum PP4 levels were low irrespective of gestational age, with a mean level of 3.0 ng/ml. There was only one case in which the serum PP4 level over 10.9 ng/ml. Mean serum PP4 levels and the frequencies of elevated serum PP4 levels were respectively 6.3 ng/ml and 11% in patients with benign ovarian neoplasms, 4.7 ng/ml and 6% in patients with endometriosis, and 5.5 ng/ml and 18% in patients with uterine myomata. The frequency of raised PP4 levels was 48% and the mean value was 13.3 ng/ml in patients with endometrial carcinoma, and the values were 44% and 13.4 ng/ml respectively in patients with cervical carcinoma. In patients with ovarian malignancy, the respective values were 15% and 7.0 ng/ml. The results did not relate to clinical stages of disease (FIGO), while the frequencies of elevated serum PP4 in patients with uterine carcinoma was over 40% in stage I diseases. Compared with other tumor markers such as carcino-embryonic antigen (CEA), tissue polypeptide antigen (TPA) and cancer antigen 125 (CA125), PP4 seems to be more promising as a marker of endometrial carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)