RESUMEN
We present the clinical and pathological findings of non-palpable breast cancer presenting an axillary mass in 8 patients at the National Cencer Center Hospital and in 89 cases previously reported in Japan. Mammography and ultrasonography were positive in 26.4% and 26.8% of cases, respectively. 82(94.3%) of 87 patients underwent mastectomy as a local control. In 19(30.6%) of 62 patients, the pathological size of the lesion was less than 5 mm. In 15 patients primary tumors could not be identified pathologically. The number of nodes involved ranged from 1-55 with a median of 5. There was no significant correlation between the number of involved nodes and the size of the axillary mass, nor between the number of involved nodes and the pathological size of the primary breast lesion. The 5-year survival rate was 59.4%. There was no statistically significant difference in 5-year survival rates between occult breast cancer and palpable breast cancer in each nodal category. Only the number of involved nodes was a reliable prognostic factor. Unlike palpable breast cancer, the pathological size of the primary tumor was not a predictor of prognosis. In this respect, the biological behavior of occult breast cancer is quite different from that of palpable breast cancer.