[Effect of sex hormone on the experimental induction of esophageal cancer].

The occurrence and the prognosis of human esophageal cancer shows a sex difference. It is assumed that sex hormone is one of the many causes of that sex difference. The effects of sex hormone on the experimental induction of esophageal cancer were investigated by the administration of chemical carcinogen. Multiple squamous cell neoplasms of the esophagus were induced by oral administration of 0.25% N-methylbenzylamine (MBeA) and 0.16% NaNO2 for 100 days or by subcutaneous (s.c.) injection of N-methylbenzyl nitrosamine (MBeN) at a dose level of 2.5mg/kg weekly for 16 weeks. The incidence of esophageal cancer in oral administration group was 42.9% in nontreated male rats, 30.0% in castrated male rats, 18.2% in estradiol s.c. injected male rats, 0% in castrated and estradiol s.c. injected male rats, 8.0% in nontreated female rats, 33.3% in castrated female rats, 33.3% in testosterone s.c. injected female rats and 36.4% in castrated and testosterone s.c. injected female rats. The incidence of esophageal cancer in s.c. injection group was 47.1% in nontreated male rats, 14.3% in early castrated and estradiol s.c. injected male rats, 23.1% in lately castrated and estradiol s.c. injected male rats, 7.7% in nontreated female rats, 33.3% in early castrated and testosterone s.c. injected female rats and 12.5% in lately castrated and testosterone s.c. injected female rats. These results showed a suppressing effect of estrogen and a promoting effect of androgen on the experimental induction of esophageal cancer.