A comparative ultrasonographic study of the structure and findings in the mammary gland in women aged 35 and 40 years.

All women aged 35 and 40 resident in one municipality in the Uusimaa province of Finland were invited for a breast examination. Hundred and thirty-eight of the subjects were 35 years old and 95 were 40 years old. Examination was performed by ultrasonography. Mammary glands were observed to contain normal glandular tissue or to have an increasingly fibrotic structure in 69.6% of the younger age group and in 72.6% of the older age group; a mastopathic structure was observable in 54.3% and 46.3%, respectively. Local findings such as solid tumors and cysts (greater than or equal to 3 mm) were present in 41.3% of the 35-year-olds and in 35.8% of the 40-year-olds. Structural and size distributions of local changes were similar in both age groups. No changes clearly suggestive of malignancy were observed in either group. On the other hand, in 13.2% of the younger age group and in 9.1% of the older age group there were borderline changes considered to fulfil at least one of the criteria for malignancy. In both groups, there were statistically significantly more (p less than 0.001) local tumors in mastopathic than in normal breasts. Ultrasonography can be used both to study mammary gland structure and to search for local changes, tumors and cancer of the breast.