• 1 January 1978
    • journal article
    • research article
    • Vol. 38  (6) , 1507-1513
Abstract
Three experiments on the induction of mammary neoplasms by total-body 11- to 100-rad neutron or 50- to 500-rad .gamma.-radiation of female Fischer or W/Fu rats are reported. Grafts of mammotropin-secreting pituitary tumor were used to elevate mammotropic hormone levels. The results confirm and extend previous reports that neutrons are more efficient in carcinoma induction than .gamma.-rays (the neutron relative biological effectiveness for 1st carcinomas was 3.68) and demonstrate that the potentiation of carcinoma induction by adrenalectomy is reversed by glucocorticoid replacement. Statistical analysis of the data by procedures that take into account time at risk as well as tumor frequency indicates that multiple mammary tumors do not occur independently (i.e., a 1st mammary neoplasm significantly increases the probability of development of another neoplasm). The statistical procedure used in this analysis is presented.