Histological features, DNA content and prognosis of breast carcinoma found incidentally or in screening.

Histology features, the nuclear DNA content and prognosis of 42 female breast carcinomas found in a physical examination based screening, 54 breast cancers found incidentally by medical personnel, and 274 breast cancers first suspected by the patient were compared. There was no significant difference in the distribution by primary tumour size (P = 0.08) or histological type (P = 0.87) of breast cancer between the screen-detected and 139 self-suspected cancers of women with similar mean age and living at the same time in the same city, but the screen-detected carcinomas were better differentiated (P = 0.0002), and had less mitoses (P = 0.008), less tumour necrosis (P = 0.004) and DNA aneuploidy (P = 0.01), smaller S-phase fractions (P = 0.009), less axillary metastases (P = 0.04), and had better outcome (P = 0.005) than self-suspected carcinomas. These parameters did not differ significantly between the screen-detected and incidentally found cancers, but incidental cancers had more often axillary metastases (P = 0.02). The results indicate that screen-detected breast carcinomas have favourable biological features suggesting low degree of malignant potential.