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Relation between clinical and mammographic diagnosis of breast problems and the cancer/biopsy rate
1Department of Surgery, Queen's University, Kingston, Ont.
Objective:
To determine the sensitivity of mammographic and clinical assessment of breast problems, independent of one another, on the ratio of cancers found to biopsies performed (cancer/biopsy rate).
Design:
A review of diagnoses from prospectively recorded and independently assessed clinical and mammographic examinations.
Setting:
The breast clinic in a university-affiliated hospital.
Patients:
Patients were considered in two age groups--under 50 years and over; 1251 patients underwent breast biopsy between September 1976 and November 1994 after clinical assessment and mammography.
Main Outcome Measure:
The cancer diagnosis rate found on biopsy as a result of clinical and mammographic findings.
Results:
In both age groups, mammography was significantly (p < 0.001) more sensitive than clinical assessment in cancer diagnosis but gave a significantly (p < 0.0001) higher rate of false-positive results. The cancer diagnosis rate was highest when lesions were assessed both clinically and mammographically as malignant but was of diagnostic benefit only to women in the under-50-year age group. The cancer rate was 12% when both assessments indicated a benign process and only 2% in women under age 50 years with clinically benign conditions who did not have mammography. Twenty-one percent of the biopsies were obtained in women with clinically normal breasts because of a mammographic abnormality and 17% of all the cancers found were clinically occult.
Conclusions:
The sensitivity of clinical assessment, particularly in premenopausal women is low and the false-positive mammography rate is high, but the cancer/biopsy rate is sufficiently high to warrant breast biopsy if either diagnostic modality suggests a cancer. When neither modality suggests cancer, the cancer/biopsy rate is 12% in both age groups.