Differential role of angiogenesis and tumour cell proliferation in brain metastases according to primary tumour type: analysis of 639 cases.

AIM: We aimed to characterize angiogenesis and proliferation and their correlation with clinical characteristics in a large brain metastasis (BM) series. METHODS: Ki67 proliferation index, microvascular density (MVD) and hypoxia-inducible factor 1 alpha (HIF-1 alpha) index were determined by immunohistochemistry in BM and primary tumour specimens. RESULTS: Six hundred thirty-nine BM specimens of 639 patients with lung cancer (344/639; 53.8%), breast cancer (105/639; 16.4%), melanoma (67/639; 10.5%), renal cell carcinoma (RCC; 52/639; 8.1%) or colorectal cancer (CRC; 71/639; 11.1%) were available. Specimens of the corresponding primary tumour were available in 113/639 (17.7%) cases. Median Ki67 index was highest in CRC BM and lowest in RCC BM (P < 0.001). MVD and HIF-1 alpha index were both highest in RCC BM and lowest in melanoma BM (P < 0.001). Significantly higher Ki67 indices, MVD and HIF-1 alpha indices in the BM than in matched primary tumours were observed for breast cancer, non-small cell lung cancer (NSCLC) and CRC. Correlation of tissue-based parameters with overall survival in individual tumour types showed a favourable and independent prognostic impact of low Ki67 index [hazard ratio (HR) 1.015; P < 0.001] in NSCLC BM and of low Ki67 index (HR 1.027; P = 0.008) and high angiogenic activity (HR 1.877; P = 0.002) in RCC. CONCLUSION: Our data argue for differential pathobiological and clinical relevance of Ki67 index, HIF1-alpha index and MVD between primary tumour types in BM patients. An independent prognostic impact of tissue-based characteristics was observed in patients with BM from NSCLC and RCC, supporting the incorporation of these tissue-based parameters into diagnosis-specific prognostic scores.

Immunohistochemical testing of BRAF V600E status in 1,120 tumor tissue samples of patients with brain metastases.

Brain metastases (BM) are frequent and carry a dismal prognosis. BRAF V600E mutations are found in a broad range of tumor types and specific inhibitors targeting BRAF V600E protein exist. We analyzed tumoral BRAF V600E-mutant protein expression using the novel mutation-specific antibody VE1 in a series of 1,120 tumor specimens (885 BM, 157 primary tumors, 78 extra-cranial metastases) of 874 BM patients. In 85 cases, we performed validation of immunohistochemical results by BRAF exon 15 gene sequencing. BRAF V600E protein was expressed in BM of 42/76 (55.3%) melanomas, 1/15 (6.7%) ovarian cancers, 4/72 (5.5%) colorectal cancers, 1/355 (0.3%) lung cancers, 2/6 thyroid cancers and 1/2 choriocarcinomas. BRAF V600E expression showed high intra-tumoral homogeneity and was similar in different tumor manifestations of individual patients. VE1 immunohistochemistry and BRAF exon 15 sequencing were congruent in 68/70 (97.1%) cases, but VE1 immunostaining identified small BRAF V600E expressing tumor cell aggregates in 10 cases with inconclusive genetic results. Melanoma patients with BRAF V600E mutant protein expressing tumors were significantly younger at diagnosis of the primary tumor and at operation of BM than patients with non-mutated tumors. In conclusion, expression of BRAF V600E mutant protein occurs in approximately 6% of BM and is consistent in different tumor manifestations of the same patient. Thus, BRAF V600E inhibiting therapies seem feasible in selected BM patients. Immunohistochemical visualization of V600E-mutant BRAF protein is a promising tool for patient stratification. An integrated approach combining both, VE1 immunohistochemistry and genetic analysis may increase the diagnostic accuracy of BRAF mutation analysis.

Preoperative diffusion-weighted imaging of single brain metastases correlates with patient survival times.

BACKGROUND: MRI-based diffusion-weighted imaging (DWI) visualizes the local differences in water diffusion in vivo. The prognostic value of DWI signal intensities on the source images and apparent diffusion coefficient (ADC) maps respectively has not yet been studied in brain metastases (BM). METHODS: We included into this retrospective analysis all patients operated for single BM at our institution between 2002 and 2010, in whom presurgical DWI and BM tissue samples were available. We recorded relevant clinical data, assessed DWI signal intensity and apparent diffusion coefficient (ADC) values and performed histopathological analysis of BM tissues. Statistical analyses including uni- and multivariate survival analyses were performed. RESULTS: 65 patients (34 female, 31 male) with a median overall survival time (OS) of 15 months (range 0-99 months) were available for this study. 19 (29.2%) patients presented with hyper-, 3 (4.6%) with iso-, and 43 (66.2%) with hypointense DWI. ADCmean values could be determined in 32 (49.2%) patients, ranged from 456.4 to 1691.8*10⁻6 mm²/s (median 969.5) and showed a highly significant correlation with DWI signal intensity. DWI hyperintensity correlated significantly with high amount of interstitial reticulin deposition. In univariate analysis, patients with hyperintense DWI (5 months) and low ADCmean values (7 months) had significantly worse OS than patients with iso/hypointense DWI (16 months) and high ADCmean values (30 months), respectively. In multivariate survival analysis, high ADCmean values retained independent statistical significance. CONCLUSIONS: Preoperative DWI findings strongly and independently correlate with OS in patients operated for single BM and are related to interstitial fibrosis. Inclusion of DWI parameters into established risk stratification scores for BM patients should be considered.

Brain metastases of gastro-oesophageal cancer: evaluation of molecules with relevance for targeted therapies.

BACKGROUND: Brain metastases (BM) of gastro-oesophageal cancer are exceedingly rare and only limited data exist on their pathobiology. MATERIALS AND METHODS: We identified tissue samples of BM of gastro-oesophageal cancer and analyzed the expression of human epidermal growth factor receptor-2 (HER2), phosphorylated signal transducer and activator of transcription-3 (pSTAT3), epithelial growth factor receptor (EGFR), V600E point mutation of the v-raf murine sarcoma viral oncogene homolog-B1 (BRAF V600E), cluster of differentiation molecule-34 (CD34), hypoxia inducible factor-1α (HIF 1-α) and Ki-67 by immunohistochemical methods. RESULTS: Our series comprised of twenty adenocarcinomas and one oesophageal squamous cell carcinoma. Three (14%), 7 (33%), 9 (43%), 18 (86%) and 0 BM specimens were scored positively for HER2, EGFR, pSTAT3, HIF1-α and BRAF V600E expression. The median Ki-67 index was 59%. The microvascular density was moderate-to-high and active intratumoral microvascular sprouting was evident in 20/21 (95%) of BMs. The HER2 and EGFR expression status were consistent between primary tumors and BM in all three assessable cases. HIF1-α and pSTAT3 expression were significantly higher in HER2-positive cases. CONCLUSION: Therapeutic use of agents targeting HER2, pSTAT3, EGFR and angiogenesis may be feasible for selected BM of gastro-esophageal cancer. HER2 positivity does not seem to predispose to brain colonization in gastro-esophageal cancer.

Frequent overexpression of ErbB--receptor family members in brain metastases of non-small cell lung cancer patients.

The ErbB receptor family has been implicated in brain metastases (BM) formation in various cancer types and specific targeted therapies are available. We investigated the overexpression of EGFR, HER2 and HER3 in BM of non-small cell lung cancer (NSCLC) patients to get a better insight on pathobiology of BM and potential drugable targets. We performed immunohistochemical analysis of EGFR, HER2 and HER3 on tissue microarrays of 131 NSCLC-BM. Fifty-one of 131 (38.9%) specimens were considered as positive for EGFR overexpression, 12/131 (9.2%) for HER2 and 27/131 (20.6%) for HER3 respectively. Sixty-nine of 131 (52.7%) of the cases showed overexpression of at least one marker. Four of 131 (3.1%) were positive for all three markers. Strong correlation was observed between HER2 and HER3 overexpression (p = 0.009; Chi-square test after Bonferroni-Holmes correction). No statistically significant correlation of EGFR, HER2 or HER3 overexpression with clinico-pathological parameters including overall survival times was observed. We observed overexpression of ErbB receptor family members, which represent established therapeutic targets in various primary tumours, in approximately half of NSCLC-BM. Further studies should investigate the role of the ErbB pathway in development of and as a therapeutic target in BM of NSCLC patients.

ALK gene translocations and amplifications in brain metastases of non-small cell lung cancer.

BACKGROUND: Increased incidence of brain metastases (BM) in non-small cell lung cancer (NSCLC) with ALK translocations was postulated, however, ALK gene aberrations in NSCLC-BM have not been investigated so far. METHODS: We investigated ALK and EML4 gene aberrations (amplifications, translocations, inversions) by fluorescent in situ hybridization (FISH) (n=175) and ALK and EML4 protein expression by immunohistochemistry (n=221) in NSCLC BM and corresponding primary tumors. RESULTS: ALK translocations were found in 4/151 (2.6%; 3 of them involving EML4) of BM of adenocarcinomas (AC), 1/9 (11.1%) of adenosquamous carcinomas (ASC), 0/5 of squamous cell carcinomas (SCC) and 0/10 of large cell carcinomas (LCC). Rearrangement of ALK without involvement of EML4 was seen in 1 AC-BM and rearrangement of EML4 without involvement of ALK in 3 AC-BM, 1 ASC-BM and 1 LCC. ALK amplifications without gene rearrangements were found in BM of 16/151 (10.6%) AC, 2/5 (40%) SCC, 0/9 ASC and one LCC. ALK translocation status was constant between BM and primary tumors in 16 evaluable cases including two cases with ALK-EML4 translocations Among these 16 cases ALK amplification was seen in two BM and none of the primary tumors. All cases with translocations but not with amplifications of ALK showed protein expression. We found no association of ALK gene status with patient age, gender or overall survival time. CONCLUSIONS: ALK translocations and amplifications are found in approximately 3% and 11% of NSCLC-BM, respectively. While ALK translocations appear to be constant between primary tumors and BM, amplifications seem to be more prevalent in BM. ALK translocation, but not ALK amplification is associated with ALK protein overexpression. Further studies are needed to determine whether NSCLC-BM patients with ALK gene aberrations may benefit from specific inhibitor therapy.

Extent of peritumoral brain edema correlates with prognosis, tumoral growth pattern, HIF1a expression and angiogenic activity in patients with single brain metastases.

To analyze the prognostic value of the extent of peritumoral brain edema in patients operated for single brain metastases (BM), we retrospectively evaluated pre-operative magnetic resonance images in a discovery cohort of 129 patients and a validation cohort of 118 patients, who underwent neurosurgical resection of a single BM in two different hospitals. We recorded clinical parameters and immunohistochemically assessed the Ki67 index, the microvascularization patterns and the expression of hypoxia-induced factor 1 alpha (HIF1a) in the BM tissue specimens retrieved at neurosurgery. Statistical analysis including uni- and multivariate survival analyses were performed. Baseline characteristics were well balanced between the discovery and validation cohorts. In univariate analysis, we found a significant association of favorable overall survival time with young patient age, high Karnofsky performance score, low graded prognostic assessment (GPA) class, absence of extracranial metastases, adjuvant treatment with whole brain radiotherapy and, surprisingly, large brain edema. In multivariate analysis, only GPA and extent of brain edema remained independent prognostic parameters. The prognostic impact of the extent of brain edema was consistent in the two patient cohorts. Furthermore, we found a significant correlation of small brain edema with brain-invasive tumor growth pattern as assessed intraoperatively by the neurosurgeon, low neo-angiogenic activity and low expression of HIF1a. Extent of brain edema independently correlates with prognosis in patients operated for single BM. In conclusion, patients with small peritumoral edema have shorter survival times and their tumors are characterized by a more brain-invasive growth, lower HIF1a expression and less angiogenic activity.