Merkel cell carcinoma - a population-based epidemiological study in Finland with a clinical series of 181 cases.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare malignancy of the skin, and its incidence is reported to be rising. The purpose of this study was to calculate its incidence and survival ratios, and to describe the clinical characteristics of Merkel cell carcinoma patients in Finland. METHODS: We calculated the incidence of MCC based on data from the Finnish Cancer Registry. In addition, patient files from hospitals and primary health care centres were reviewed for detailed data on the treatment and disease recurrence of 181 patients diagnosed with MCC in Finland during 1983-2004, and relative survival ratios were calculated for them. RESULTS: The incidence (per 100,000) of MCC in Finland in 1989-2008 was 0.11 for men and 0.12 for women, adjusted for age to the world standard population. The mean age at diagnosis was 76 years (range 27-100), and 69% of the patients were women. The most common site of the primary tumour was the head and neck (53%). No extra benefit was gained from a wide surgical margin (≥ 2 cm) compared to a margin of 0.1-0.19 cm, but an intralesional excision was more often associated with local recurrence. None of the patients with Stage I-II disease who had received postoperative radiotherapy to the tumour bed had a local recurrence. The 5-year relative survival ratio amongst men was 36% (95% confidence interval 20-54%), and amongst women 69% (56 to -82%). CONCLUSIONS: MCC is a rare disease in Finland, with incidence rates similar to those in the other Nordic countries. Our results support the view that complete excision with clear margins and post operative radiotherapy decrease local recurrences.

Merkel cell polyomavirus infection, large T antigen, retinoblastoma protein and outcome in Merkel cell carcinoma.

PURPOSE: Merkel cell carcinoma (MCC) is rare skin cancer that is often associated with Merkel cell polyomavirus (MCPyV) infection. Polyomaviruses repress tumor suppressor proteins, thus influencing cell-cycle progression, but the effect of MCPyV on the key cell-cycle regulating proteins is poorly understood. EXPERIMENTAL DESIGN: We evaluated expression of the MCPyV large T-antigen (LTA), Ki-67, and the key putative tumor suppressor proteins, the retinoblastoma protein (RB and phospho-RB) and p53, and their regulatory proteins (cyclin D1, cyclin E, p16, p21, p27, and MDM2) by using immunohistochemistry from tumors of 91 MCC patients identified from a population-based nationwide cohort. Tumor MCPyV DNA was measured by using quantitative PCR, and TP53 mutations were identified with sequencing. RESULTS: MCPyV LTA expression was strongly associated with presence of MCPyV DNA in tumor, and it was almost invariably associated with tumor RB expression (P < 0.0001 for both comparisons). Both MCC LTA and RB expression were strongly associated with favorable MCC-specific and overall survival in univariable analyses (P ≤ 0.01 for all four analyses). Presence of MCPyV LTA was also associated with the female gender, the intermediate type of tumor histology, location of the tumor in a limb, cell proliferation rate, and absence of p53 expression. TP53 mutations were detected only in MCPyV DNA-negative tumors. CONCLUSIONS: MCPyV DNA-positive MCC has several clinical and molecular features that differ from MCPyV DNA-negative cancers. MCPyV-associated MCCs express RB, but may not harbor TP53 mutations. These findings provide further support that MCPyV causes the majority of MCCs.

Association of Merkel cell polyomavirus infection with tumor p53, KIT, stem cell factor, PDGFR-alpha and survival in Merkel cell carcinoma.

Most Merkel cell carcinomas (MCCs) contain Merkel cell polyomavirus (MCPyV) DNA, and the virus likely has a pivotal role in tumor pathogenesis. p53 and the KIT receptor tyrosine kinase have also been implicated in MCC pathogenesis, but little is known about their association with MCPyV infection. We identified 207 patients diagnosed with MCC in Finland in 1979-2004 and reviewed the histological diagnoses. Adequate clinical information, tumor tissue and DNA were available from 87 confirmed MCC cases. Presence of MCPyV DNA was assessed using quantitative PCR; p53, KIT, phospho-KIT, stem cell factor (SCF) and PDGFRα expression using immunohistochemistry and presence of mutations in KIT exons 9, 11, 13 and 17 and PDGFRA exons 10, 12, 14 and 18 using DNA sequencing. Most (77.0%) of the 87 tumors contained MCPyV DNA and 37 (42.5%) expressed KIT, whereas PDGFRα, p53, SCF and pKIT expression was less common (31.9, 22.8, 8.6 and 4.8%, respectively). No KIT or PFGFRA mutations were detected, but 10 (12.5%) of the 80 tumors studied harbored common PDGFRA exon 10 S478P substitution. Tumor p53 and KIT expression were associated with absence of MCPyV DNA (p = 0.01 and 0.009, respectively). Tumor p53 expression was associated with unfavorable MCC-specific survival (p = 0.021) and overall survival (p = 0.046), but tumor KIT expression only when stratified by presence of MCPyV DNA. The results suggest that p53 and KIT expression are associated with absence of MCPyV DNA in MCC, and that the molecular pathogenesis of MCC is multifactorial.

Vascular invasion is an early event in pathogenesis of Merkel cell carcinoma.

This study investigated vascular and especially lymphovascular invasion in primary Merkel cell carcinoma and its value as a prognostic factor. Paraffin-embedded blocks prepared from tumor samples obtained from 126 patients diagnosed with Merkel cell carcinoma in 1979-2004 were immunohistochemically stained using antibodies CD31 and D2-40 to detect intravascular tumor emboli. This finding was compared with the clinical data and the disease outcome. Intravascular tumor cells were observed in 117 (93%) of the samples. The majority, 83 (66%), showed only lymphovascular invasion. Only blood vascular invasion was seen in four (3%) samples. In all, 30 (24%) samples demonstrated both lymphovascular invasion and blood vascular invasion. In only nine (7%) samples, there was no invasion within the vascular structures. The tumors lacking invasion were significantly smaller (P<0.01 and alpha=0.050) than those with vascular invasion, although lymphovascular invasion was observed even in the smallest tumor (0.3 cm) of this study. Already in the early stages of the disease, Merkel cell carcinoma seems to have the capacity to penetrate vessel walls. Our finding of the high frequency of lymphovascular invasion might therefore explain the extremely aggressive clinical behavior of Merkel cell carcinoma. This may support the role of sentinel node biopsy even in the case of very small primary Merkel cell carcinoma tumors.

Second cancers following the diagnosis of Merkel cell carcinoma: a nationwide cohort study.

Merkel cell carcinoma (MCC) is a rare neuroendocrine carcinoma of the skin. MCCs and some other skin cancers, such as basal cell carcinomas, frequently harbour Merkel cell polyomavirus DNA. The purpose of the study was to investigate the frequency of second cancers following the diagnosis of MCC. We studied the incidence of second primary cancers after the diagnosis of MCC from the files of the Finnish Cancer Registry in 1979-2006. Among the 172 MCC patients identified a total of 34 second primary cancers were detected in 30 individuals after the diagnosis of MCC. Female MCC patients were diagnosed with 25 subsequent cancers (SIR, 2.35; 95% CI, 1.52-3.47; p<0.001) and male patients with 9 cancers (SIR, 2.32, 95% CI, 1.06-4.40; p<0.05). The MCC patients had an increased risk for a subsequent cancer (any site) compared to age-, gender- and calendar period-matched general population (standardized incidence ratio [SIR] 2.34; 95% confidence interval [CI], 1.62-3.27). The risks for basal cell carcinoma of the skin (O=11), SIR, 3.48; 95% CI, 1.74-6.22 and chronic lymphocytic leukemia (O=2), SIR, 17.9; 95% CI, 2.16-64.6 were significantly elevated. The SIRs for an overall second primary cancer risk did not change markedly with time since the diagnosis of MCC. We conclude that patients diagnosed with MCC have an increased risk for a second cancer. This risk may in part result from shared etiological factors between MCC and other tumour types, such as immunosuppression or possibly Merkel cell polyomavirus infection.

Expression of MMP-10, MMP-21, MMP-26, and MMP-28 in Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is an aggressive cutaneous tumor with poor outcome and increasing incidence. We examined by immunohistochemistry the expression of three novel matrix metalloproteinases (MMPs)-MMP-21, MMP-26, and MMP-28-in 44 primary MCC tumors and six lymph node metastases while MMP-10 served as a positive control. Their mRNA expression was also studied in the UISO MCC cell line basally and after various stimulations using quantitative real-time PCR. MMP-28 was observed in tumor cells of 15/44 samples especially in tumors <2 cm in diameter (p = 0.015) while 21/44 specimens showed MMP-28 in the tumor stroma. Expression of MMP-21 was demonstrated in tumor cells of 13/43 samples. MMP-26, instead, was positive in stromal cells (17/44) and its expression associated with tumors >or=2 cm in diameter (p = 0.006). Stromal expression of MMP-10 was the most frequent finding of the studied samples (31/44), but MMP-10 was detected also in tumor cells (17/44). Most of the metastatic lymph nodes expressed MMP-10 and MMP-26. MMP-10, MMP-21, and MMP-28 mRNAs were basally expressed by the UISO cells, and the corresponding proteins were detectable by immunostaining of cultured cells. IFN-alpha and TNF-alpha downregulated MMP-21 and MMP-28 expression. Our results suggest that novel MMPs may have a role in MCC pathogenesis: especially that MMP-26 expression in stroma is associated with larger tumors with poor prognosis. Expression of MMP-21 and MMP-28 seems to associate with the tumors of lesser malignant potential. We also confirm the previous finding on the role of MMP-10 in MCC pathogenesis.

Tumour microvessel endothelial cell KIT and stem cell factor expression in human solid tumours.

AIMS: To assess KIT receptor tyrosine kinase and stem cell factor (SCF, KIT ligand) expression in tumour microvessel endothelial cells. METHODS AND RESULTS: KIT and SCF expression were studied in 248 human tumours consisting of 15 different histological types using immunohistochemistry and in situ hybridization for KIT messenger RNA. Moderate to strong intratumoral endothelial cell KIT expression was present in 11 of the 15 tumour types, and was most common in glioblastoma (58%), mixed embryonal carcinoma with teratoma (33%) and renal clear cell carcinoma (29%). Results of in situ hybridization were in line with those obtained with immunohistochemistry in the cases studied (n = 9). Marked SCF expression was uncommon in tumour endothelial cells, but frequent in perinecrotic tumour cells. Patients with glioblastoma with moderate to strong endothelial cell KIT expression had more favourable survival than those whose tumour showed little or no expression (P = 0.024). Glioblastoma patients whose tumour expressed SCF had an unfavourable outcome compared with those with tumour with weak or no expression (P = 0.034). CONCLUSIONS: Intratumoral microvessels of several types of human malignant tumours express KIT. Tumour cell SCF expression and absence of marked endothelial cell KIT expression are novel adverse prognostic features in glioblastoma.

Incidence of Merkel cell carcinoma in renal transplant recipients.

BACKGROUND: The risk factors for Merkel cell carcinoma (MCC), a rare type of skin cancer, are poorly understood. Some evidence suggests that MCC is more common in individuals with abnormal immune function resulting from viral infection, autoimmune disease or organ trans- plantation. METHODS: The national Renal Transplant Registry and the Finnish Cancer Registry data were searched for recipients of a renal transplant who were diagnosed with MCC. The MCC diagnoses were confirmed using immunohistochemistry. RESULTS: Three cases of MCC were detected among 4200 individuals who underwent renal transplantation from 1967 to 2005 [expected number 0.05, standardized incidence ratio (SIR) 66, 95% CI 14-194, P <0.001]. The latency period between the transplant and detection of MCC ranged from 6 to 19 years. In all three cases, the cause of transplantation was an autoimmune disease. All three died from aggressive MCC with a survival time ranging from 0.5 to 2.1 years. CONCLUSIONS: The results indicate that the risk of MCC is greatly increased among subjects who have undergone renal transplantation. The course of the disease appears aggressive in this patient population. The physicians who treat recipients of a kidney transplant should be aware of the substantially increased risk of MCC.

Clinical factors associated with Merkel cell polyomavirus infection in Merkel cell carcinoma.

BACKGROUND: Merkel cell carcinoma is a rare malignancy of the skin. Integration of Merkel cell polyomavirus (MCPyV) DNA to the tumor genome is frequent in these cancers. The clinical consequences of MCPyV infection are unknown. METHODS: We analyzed formalin-fixed paraffin-embedded Merkel cell carcinoma tissue samples from 114 of 207 patients diagnosed with Merkel cell carcinoma in Finland from 1979 to 2004 for the presence of MCPyV DNA with the use of polymerase chain reaction (PCR), quantitative PCR, and DNA sequencing and examined associations between tumor MCPyV DNA status and histopathologic factors and survival. The median follow-up time after Merkel cell carcinoma diagnosis for subjects who were alive was 9.9 years (range = 4.9-21.9 years). All P values are two-sided. RESULTS: MCPyV DNA was present in 91 carcinomas (79.8%). Compared with MCPyV DNA-negative cancers, MCPyV DNA-positive cancers were more often located in a limb (40.7% vs 8.7%, P = .015) and less frequent in patients who had regional nodal metastases at diagnosis (6.6% vs 21.7%, P = .043). Patients with MCPyV DNA-positive tumors had better overall survival than those with MCPyV DNA-negative tumors (5-year survival: 45.0% vs 13.0%, respectively; P < .001, two-sided log-rank test). CONCLUSIONS: MCPyV infection is associated with clinical outcomes in patients with Merkel cell carcinoma. These findings lend support to the hypothesis that viral infection is frequently associated with the pathogenesis of Merkel cell carcinoma.

Expression of endostatin in merkel cell carcinoma.

BACKGROUND: The aim of this study was to examine the expression of endostatin in Merkel cell carcinoma (MCC) and to correlate the expression with tumour growth and the development of metastasis. PATIENTS AND METHODS: The study comprised 19 patients treated for MCC at the Helsinki University Hospital, Helsinki, Finland between 1987 and 2003. Endostatin expression was studied by immunohistochemistry. The correlations between the quantitative expression of endostatin and tumour parameters were analysed statistically. RESULTS: The expression of endostatin was documented in only 40% of the samples. Endostatin correlated negatively with tumour size, and was expressed in 30% of the large and 56% of the small tumours. There was no difference in expression between tumours expanding to metastases and tumours with more indolent behaviour. The simultaneous expression of vascular endothelial growth factor receptor-2 and endostatin was distinguished in small-sized tumours. CONCLUSION: This study showed a correlation between endostatin expression and small tumour size in Merkel cell carcinoma. This finding was further confirmed by the finding that tumours positive for VEGFR-2, but not for endostatin, seemed to be larger than tumours that showed simultaneous expression of VEGFR-2 and endostatin.

Expression of vascular endothelial growth factor receptor-2 in Merkel cell carcinoma.

BACKGROUND: The aim of this study was to examine the expression of vascular endothelial growth factor receptor-2 (VEGFR-2) in Merkel cell carcinoma (MCC) and to correlate the expression with tumour growth and the development of metastasis. PATIENTS AND METHODS: The study included 21 patients treated for MCC at Helsinki University Hospital, Helsinki, Finland between 1987 and 2003. The VEGFR-2 expression was studied by immunohistochemistry. The correlations between the quantitative expression of VEGFR-2 and tumour size and metastatic dissemination were analyzed statistically. RESULTS: VEGFR-2 was expressed in 91% of the large (> or =2 cm) and 70% of the small (<2 cm) tumours. There was a stronger positive correlation between expression of VEGFR-2 and tumour size than between VEGFR-2 and metastatic potential. CONCLUSION: A correlation between the expression of pro-angiogenic marker and tumour size was established. Our results indicate that inhibiting angiogenesis could be a treatment option for MCC. The role of neovascularization in the metastatic process in MCC remains to be determined.