Hereditary breast cancer in Finnish women.

OBJECTIVE

To estimate the incidence of hereditary breast cancer seen in one Finnish hospital and to study the characteristics of the disease.

DESIGN

Retrospective questionnaire and study of Finnish Cancer Registry.

SETTING

University hospital, Finland.

SUBJECTS

All 669 patients operated on for breast cancer 1986-90.

MAIN OUTCOME MEASURES

Type of breast cancer and morbidity in hereditary compared with other forms of breast cancer. The definition of hereditary breast cancer requires that at least three first degree relatives, inclusive of the proband, have breast cancer.

RESULTS

Of the 669 patients 495 answered the questionnaire. Ten patients (2%) were classified as having hereditary breast cancer. The remaining 485 patients had other types of breast cancer by definition. Of those that were not hereditary 89 (18%) were classified as having familial breast cancer. Of the 495 patients 396 (80%) were classified as sporadic. The mean age of the patients at onset of the disease was 56 years in the hereditary group, 55 years in the familial group, and 57 years in the sporadic group. One patient (10%) in the hereditary, five (6%) in the familial, and 17 patients (4%) in the sporadic group had bilateral disease. Ductal carcinoma was most common in all groups of patients with breast cancer.

CONCLUSION

There were no statistical differences in this series in the age at onset, incidence of bilateral disease, stage, and histopathology among the groups, although bilateral and lobular cancer were seen more often in the group with hereditary breast cancer.