HER-2 protein overexpression in metastatic breast carcinoma found at autopsy.

Objective: The overexpression of HER-2 protein has generally been considered to be consistent in primary and metastatic tumor tissues. We evaluated HER-2 protein overexpression levels in 31 autopsied cases. Methods: Hematoxylin-eosin staining and immunohistological staining Hercep Test II (TM) were performed on the primary tumors and the lung, liver, brain and bone metastatic tumors. Results: Nine (29%) of the 31 primary tumors were HER-2 score 3+ and HER-2 score 3+ cases were significantly more frequent in carcinomas of nuclear Grade 3 than in those of Grade 1 or 2. In these 31 patients, the HER-2 status in the primary tumors was consistent with the metastatic foci of the lung, liver, brain and bone in 96% (25 of 26), 91% (21 of 23), 100% (12 of 12) and 85% (11 of 13), respectively. With regard to the nine patients with HER-2 score 3+ primary tumors, the HER-2 status in the primary tumors was consistent with the metastatic foci of the lung, liver, brain and bone in 87% (seven of eight), 78% (seven of nine), 100% (only one) and 33% (one of three), respectively. In 11 (92%) of the 12 patients with brain metastasis, the HER-2 was not overexpressed. Conclusions: Even in the far-advanced stages of autopsy, HER-2 status of the primary tumors appeared to be maintained especially in the foci of the lung, liver and brain metastases. As there was a high degree of agreement in HER-2 status between the primary tumors and the metastatic foci to the lung, liver and brain, it is considered to be reasonable to treat patients with such metastatic foci based on the HER-2 status of the primary tumors.