Prolactin: its role in advanced tongue cancer

Serum prolactin was measured pretherapeutically and sequentially thereafter using immunoradiometric assay method in 37 male patients with advanced tongue cancer and compared with 23 healthy, age-matched controls. Prolactin levels were correlated with age, various clinicopathologic parameters, overall survival, and patients with response and those with progressive disease. Patients with advanced tongue cancer had higher prolactin levels than controls (P < 0.02), but intergroup variation in prolactin was not observed when considering the age, site of the lesion, disease stage, histologic grade, and keratin. Of the patients, 30% had hyperprolactinemia (prolactin > 15.0 ng/ml). To assess the prognostic significance of pretherapeutic prolactin level, the patients were divided according to the cutoff level of prolactin (15.0 ng/ml). Hyperprolactinemic patients had more unfavourable prognosis than patients with prolactin < 15.0 ng/ml (X2 = 2.91, df = 1, P < 0.0037). In monitoring disease course, patients who responded to treatments had decreased prolactin levels at the end of 18 months as compared to their pretherapeutic levels (P < 0.01). In patients who subsequently developed progressive disease within 18 months, prolactin levels reduced initially at response, whereas with disease progression, prolactin levels increased significantly (P < 0.05). The positive and negative predictive value of prolactin was 100%. Immunohistochemical localization confirmed the ectopic production of prolactin by tongue tumors. In conclusion, our data indicate that hyperprolactinemia may be an independent predictor of short-term prognosis; circulating prolactin may be used as a marker for monitoring disease course in patients with advanced tongue cancer, and prolactin is produced ectopically by tongue tumors.