gms | German Medical Science

Objective: Recently Baumert and colleges evaluated brain metastases for the existence of an infiltration zone in 45 autopsies (Baumert et al., 2006). The chief origin of the metastases was lung cancer (>50%), followed by 5 cases of melanoma and breast cancer. 78 metastases were investigated and 63% showed an infiltration zone with cancer cells invading the adjacent brain tissue. In some samples they detected cancer cells in the benign tissue one mm beyond the microscopic edge of the solid tumor. In our retrospective study, we investigated 15 brain metastases of breast cancer and 8 metastases of non small cell lung cancer (NSCLC) patients for carcinoma cell infiltration into adjacent brain tissue.

Methods: Tumor tissue for immunohistochemistry (IHC) was obtained from 23 neurosurgically resected brain metastases with approval of the local ethics committee. The formalin-fixed and paraffin-embedded tissues were HE stained and IHC was performed with anti-pan-cytokeratin and anti-E-Cadherin. The brain metastases interface was demonstrated by anti-GFAP IHC. First the tissues were analyzed for the presence of adjacent brain tissue then the brain tissues were investigated for invading carcinoma cells. Scoring was regareded as being positive for carcinoma infiltration by the existence of more than one cytokeratin or E-Cadherin positive cell in the brain tissue.

Results: In 13/15 samples of breast cancer brain metastases, adjacent tissue was present and in 11 metastases, cancer cells infiltrated adjacent brain tissue. 4/8 NSCLC samples could be evaluated. In 2 samples carcinoma cells had invaded into the adjacent brain. Altogether we detected an infiltration zone in 56% of the carcinoma metastasis.

Conclusions: In comparison to the recent autopsy study, we demonstrate the existence of an infiltration zone in more than 50% of lung and breast cancer brain metastases, at the time of surgical resection already. Considering that six metastases could not be evaluated due to the lack of adjacent brain within the specimen, this figure may even be underestimating the degree of microscopic dissemination. Along these lines, a Korean study showed less local recurrence after microscopic total resection followed by radiotherapy compared to control group (Yoo et al., 2009). This study also underlines the existence of an active cancer cell infiltration which may require a reconsideration of current resection techniques for at least some types of brain metastases.