Immunohistochemical study of the epithelial-mesenchymal transition phenotype in cancer of unknown primary: incidence, correlations and prognostic utility.

BACKGROUND: The epithelial to mesenchymal transition (EMT) has been associated with metastatic dissemination and poor outcome in several solid tumour types. Our aim was to study its incidence and its prognostic significance in cancer of unknown primary (CUP). PATIENTS AND METHODS: One hundred tumour samples of CUP were loaded in tissue microarrays and were studied for immunohistochemical (IHC) expression of E-cadherin, N-cadherin, vimentin, the EMT transcription factor (SNAIL) and the stem cell marker octamer-binding transcription marker 4(OCT4). An EMT phenotype was defined as low expression of E-cadherin, expression of N-cadherin with/without vimentin with concomitant expression of SNAIL, as assessed by percentage of tumour cell staining. RESULTS: Among 100 CUP cases, the histological diagnosis was adenocarcinoma in 55, squamous carcinoma in 20 and undifferentiated carcinoma in 15, with a high grade seen in 46. Therapy consisted of palliative chemotherapy, mostly platinum based. The median progression-free survival and overall survival (OS) were 7 and 12 months respectively. Distributional studies resulted in selection of IHC cut-offs for E-cadherin (negative when expressed in <60% of tumour cells), N-cadherin, vimentin (positive when expressed in ≥40% of tumour cells), SNAIL (positive when stained in ≥80% of tumour cells). An EMT phenotype was observed in 8 cases (8.1%) and was strongly associated with poor OS (median OS EMT(-)=13 months vs. median OS EMT(+)=8 months, p=0.023). When we used staining intensity (H-Score), an EMT phenotype was observed in 16 patients and carried borderline adverse prognostic utility for outcome (median OS 9 vs. 14 months, p=0.07). The presence of the EMT phenotype correlated significantly with male gender, high grade and presence of visceral metastases (χ(2) p<0.05), while EMT mediator expression was correlated to high NOTCH 2/3 expression. Other factors, prognostic for poor survival, were male gender, PS≥2, non-platinum therapy (χ(2) p<0.05). CONCLUSION: EMT is infrequently seen in tumours of CUP. However, an adverse prognostic significance for patient outcome has been identified and may warrant studies of therapeutic targeting.

Profiling immunohistochemical expression of NOTCH1-3, JAGGED1, cMET, and phospho-MAPK in 100 carcinomas of unknown primary.

Cancer of unknown primary (CUP) is a heterogeneous entity, managed on the basis of "one size fits all" therapeutic concepts; insights into the molecular biology of CUP are urgently needed. We retrospectively examined the immunohistochemical (IHC) expression of Notch1, 2, 3, Jagged1, cMET, and pMAPK biomolecules in 100 CUP tumors using tissue microarrays, aiming to study their correlation to clinicopathologic characteristics and prognostic utility for patient outcome. Notch3 and pMAPK were most frequently expressed (97 and 91 %, respectively). A linear correlation of Notch3 and cMET expression was found (p = 0.001), while pMAPK emerged as the major adverse prognostic factor (median overall survival OS 9 vs. 17 months, p = 0.016), carrying also a significantly positive predictive value (p = 0.02). Our study indicated a favorable prognostic impact of cMET expression in CUP, both in univariate (median OS 15 vs. 9 months, p = 0.05) and in multivariate analysis (Relative Risk RR for death 0.48, p = 0.025). cMET and Notch3 expression were found to be statistically more frequent in squamous carcinomas (positive in 90 % of cases), associated with a unique metastatic IHC pattern (cMET-high in soft tissue/lymph node metastases, p < 0.001, Notch3-high in visceral, peritoneal/pleural and soft tissue/lymph node metastases, p < 0.001). Our study points to the MAPK and cMET axes as crucial in defining cancer progression and outcome in CUP patients and, if validated, could justify attempts at their therapeutic modulation.