Nuclear DNA content in mammary carcinomas in women aged 35 or younger.

Nuclear DNA content was studied in cytologic preparations obtained from 50 patients aged 35 or less with primary mammary carcinoma. As many as 90% of the tumors were aneuploid, i.e., exhibited DNA profile types III and IV. The cytologic diagnosis was confirmed by histologic examination in 46 patients. The majority of these tumors, 83%, were invasive ductal carcinomas, while medullary carcinomas constituted 13% of the surgical material. As judged from their DNA profiles, most mammary carcinomas in this age group would be tumors of high malignancy potential. This does not seem, however, to influence the prognosis of young women with breast cancer as much as would be expected, possibly because of a better-functioning immune surveillance system in this age group.