Influence of reducing luxury calories in the treatment of experimental mammary carcinoma.

The aim of this study was to investigate the influence of dietary calorie intake at three different fat levels on (a) the growth of established methylnitrosourea (MNU)-induced mammary carcinoma, (b) the reappearance of mammary carcinomas after surgical removal, and (c) the growth of manifest lesions in animals treated with the cytostatic agent hexadecylphosphocholine (HPC). A reduction of calories by 30% significantly inhibited tumour growth of manifest mammary carcinomas in rats, without having a negative influence on body weight gain. After chemotherapeutic treatment no significant dietary influence was observed besides the high antineoplastic efficacy of HPC, but when feeding calorically restricted diets to surgically treated animals the number of reappearing tumours was considerably smaller (P = 0.06) than after feeding the diets ad libitum. The fat content of the diets did not influence the growth of manifest mammary carcinomas. No significant dietary effects were exerted on oestradiol or testosterone levels in untreated tumour bearing animals. An elevation of oestradiol levels was observed when animals were subjected to HPC and fed a high calorie diet. An elevation of testosterone levels was assessed after surgical treatment of the rats, irrespective of fat content and calorie level. Our results suggest that a reduction of calories can inhibit growth of manifest mammary carcinomas and has impeding effects on tumour development after surgical removal. After effective chemotherapeutic treatment the additional influence of dietary changes was of less relevance. Furthermore, our data do not establish any association between growth inhibition of mammary tumours, caused by the mild caloric restriction, and altered oestradiol or testosterone production.