The influence of mammography screening on the pathological panorama of breast cancer.
The pathologist describes the biological domain of breast cancer in which the clinician works. Over the last 20 years there have been indications that the biological domain has shifted following the introduction of fine-needle biopsies, clinical mammography, and later screening mammography. The most commonly used parameters for staging, classification and grading of cancer in some respects probably reflect the biological domain. We describe how the pathological panorama of breast cancer has changed with the introduction of population-based mammography screening. Our experiences are based on a consecutive series of 1961 breast cancers diagnosed from 1977 to 1994 in a region where screening mammography was introduced in 1988. All results, including histological classification and grading were prospectively registered in a computerized data base. There were more comedo than tubuloductal carcinomas and there was a corresponding preponderance of grade III tumours in the youngest and a high incidence of tubuloductal, lobular and colloid cancers in the oldest age group. The proportion of women with comedo carcinoma decreased after 1987. Looking at changes in the grade distribution after 1987, the proportion of women with grade I tumours increased and grade III tumours decreased in women over 50 years of age, but in the youngest women only marginal changes were noted. Very few in situ carcinomas were diagnosed in the prescreening period. About 11% of all tumours were in situ after 1987. The percentage of node-positive cancer decreased in the screening period in all histological types of cancer regardless of tumour size. The percentage of small tumours < or = 20 mm increased with time, though less so for comedo carcinomas. Comedo carcinomas dominate among the largest cancers most frequently detected clinically. From a biological standpoint it is interesting to note that screening seems to entail a larger shift in the biological domain in older as compared to younger women. Furthermore, comedo carcinomas seem to be less well detected by the screening procedure.
Lindgren
A
A
Department of Pathology, Academic Hospital, Uppsala, Sweden.
Holmberg
L
L
Thurfjell
E
E
D000328:Adult; D001943:Breast Neoplasms / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008327:Mammography; D008403:Mass Screening; D008875:Middle Aged; D011446:Prospective Studies