Immunohistochemical characteristics of brain metastases and corresponding primary lung cancer

Purpose: To study brain metastases (BM) and their corresponding primary lung cancers (LCs). Methods: Surgically resected BMs and their corresponding primary LCs from 30 patients (25 men, 83%, age 55 +/- 9 years) were studied: 21 adenocarcinomas (ACs), 5 squamous cell carcinomas (SCCs), 4 small cell lung carcinomas (SCLCs). The histological subtype, immunohistochemical expression of TTF1, p63, Ki67 (proliferative activity), CD31, number of intratumoral microvessels, (NIM) and survival were evaluated. Results: There was a different histological structure in 47% of the cases of ACs of the lung in comparison with the corresponding metastasis, but none in SCC and SCLC. TTF-1 was expressed in a greater number of ACs (n=20; 95%), with lower mean expression levels, while the corresponding BM expressed the marker less frequently (n=16; 76%) with higher mean expression values (p=0.011). P63 was expressed in all SCCs (p=0.68). Cytokeratin 7 was expressed equally in all ACs. Ki-67 proliferative index (PI) was higher in SCLC than in AC (p=0.008), in SCLC BM than in AC BM (p<0.001), and in SCLC BM than in SCC BM (p=0.008). The Ki-67 PI in BM was higher than in AC (p=0.003), SCC (p=0.048), but without difference in SCLC (p=0.141). CD31 NIM was higher in AC than in SCLC (p=0.003), in SCC than in SCLC (p=0.009), while no difference between AC and SCC was found (p=0.467). There were no differences between LC/BM in the NIM. Survival after surgery for LC was significantly longer in AC than in SCLC (p=0.017). SCLC histology and Ki67>18% were established as negative prognostic factors after surgery for LC. Such factors were not found after surgery for BM. Conclusion: There are differences between primary LC and corresponding BM - in histology, immunohistochemical expression and proliferative activity, but there are no significant differences in vascularization. SCLC histology and Ki67>8% may represent negative prognostic factors after surgery for LC with BM.