Comparative Study of Diagnostic Efficiency of Mammography and Ultrasonography for Breast Cancer

Abstract

We performed a study of 448 women with breast cancer who visited the breast clinic of Nagano Cancer Center, and underwent mammography (MMG) and ultrasonography (US) at the last examination, between October 1983 and December 1993. These women subsequently underwent surgery at several hospitals after referral from our center. Definitive diagnoses of breast cancer were made histopathologically.
Both MMG and US findings were graded using five-step criteria (indicating the level of malignancy) from I (normal) to V (definite malignancy) The diagnostic efficiencies of the two examinations were then compared clinicopathologically. Furthermore, on the basis of the results obtained, we considered supplemental diagnostic methods that could be introduced for mass screening of breast cancer.
1) There was a significant difference between the incidence of cases diagnosed as V·IV· III b (malignancy) by US (71.9%) and those diagnosed by MMG (60.9%).
2) Among cases suspected to be breast cancer by palpation, the proportion diagnosed as V · IV·III b (malignancy) by US (83.3%) was significantly higher than that diagnosed by MMG (73.7%). Among cases suspected to be mastopathy by palpation, the proportion diagnosed as malignant by US was higher than that diagnosed by MMG.
3) The false negativity rate for palpation combined with MMG was higher than that for palpation with US.
4) Among cases without palpable masses, the proportion diagnosed as malignant by MMG was higher than that diagnosed by US. However, for palpable tumors less than 5.0 cm in diameter, the proportion of cases diagnosed as malignant by US was higher than that diagnosed by MMG.
5) In terms of the gross appearance of the cut surface, grade of cancer invasion, histological type and grade of chubbiness, the diagnostic efficiency of US was shown to be slightly better than that of MMG.
The above results suggest that US should be considered as a supplemental method for introduction to mass screening of breast cancer.