Analysis of MYB oncogene in transformed adenoid cystic carcinomas reveals distinct pathways of tumor progression.

Adenoid cystic carcinomas can occasionally undergo dedifferentiation, a phenomenon also referred to as high-grade transformation. However, cases of adenoid cystic carcinomas have been described showing transformation to adenocarcinomas that are not poorly differentiated, indicating that high-grade transformation may not necessarily reflect a more advanced stage of tumor progression, but rather a transformation to another histological form, which may encompass a wide spectrum of carcinomas in terms of aggressiveness. The aim of this study was to gain more insight in the biology of this pathological phenomenon by means of genetic profiling of both histological components. Using microarray comparative genomic hybridization, we compared the genome-wide DNA copy-number changes of the conventional and transformed area of eight adenoid cystic carcinomas with high-grade transformation, comprising four with transformation into moderately differentiated adenocarcinomas and four into poorly differentiated carcinomas. In general, the poorly differentiated carcinoma cases showed a higher total number of copy-number changes than the moderately differentiated adenocarcinoma cases, and this correlated with a worse clinical course. Special attention was given to chromosomal translocation and protein expression of MYB, recently being considered to be an early and major oncogenic event in adenoid cystic carcinomas. Our data showed that the process of high-grade transformation is not always accompanied by an accumulation of genetic alterations; both conventional and transformed components harbored unique genetic alterations, which indicate a parallel progression. Our data further demonstrated that the MYB/NFIB translocation is not necessarily an early event or fundamental for the progression to adenoid cystic carcinoma with high-grade transformation.

Gene amplification and protein overexpression of EGFR and ERBB2 in sinonasal squamous cell carcinoma.

BACKGROUND: Sinonasal squamous cell carcinomas (SNSCCs) are rare tumors with no etiologic link to tobacco or alcohol, as opposed to other squamous cell carcinomas of the head and neck. Despite improvements in the field of surgery and radiotherapy, patients with these tumors still face a very unfavorable prognosis, partly because of their localization in a complex anatomic area, which has special relevance for surgery and postoperative treatment. Therefore, there is a need for new therapeutic possibilities for patients with these tumors. METHODS: Gene copy numbers of epidermal growth factor receptor (EGFR) and v-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ERBB2) were analyzed by fluorescence in situ hybridization and multiplex ligand-dependent probe amplification, and protein expression was evaluated by immunohistochemistry in 54 SNSCC specimens. The results were correlated with clinicopathologic and follow-up data. RESULTS: EGFR gene copy number increases were observed in 20 of 45 tumors (44%), and 21 of 54 tumors (39%) had EGFR protein overexpression. Eight of 38 tumors (21%) had ERBB2 copy number increases, and 4 of 54 tumors (7%) exhibited elevated protein expression levels. Both copy number increases and protein overexpression of EGFR and ERBB2 were mutually exclusive. v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations were absent in 37 tumors that were analyzed. CONCLUSIONS: A substantial proportion of SNSCCs carried alterations in EGFR or ERBB2. Together with the absence of KRAS mutations, these findings indicate that therapies targeting these molecules may be promising additions to the therapeutic options for patients with SNSCC.

Predictive value of EGFR-PI3K-pAKT-mTOR-pS6 pathway in sinonasal squamous cell carcinomas. / Valor pronóstico de la ruta de EGFR-PI3K-pAKT-mTOR-pS6 en los carcinomas epidermoides nasosinusales.

BACKGROUND AND OBJECTIVES: We have previously indicated that EGFR has a role in carcinogenesis in a subgroup of sinonasal squamous cell carcinomas (SNSCC). In addition, EGFR activates 2 of the most important intracellular signalling pathways: PI3K/pAKT/mTOR/pS6 and MAP pathway kinases. The objective of this study was to evaluate the involvement of the EGFR/PI3K/pAKT/mTOR/pS6 pathway and its relationship with clinical-pathological parameters and follow-up of sinonasal squamous cell carcinoma. MATERIAL AND METHODS: The immunohistochemical expression of different components of the PI3K/AKT/mTOR/pS6 pathway and its relationship with various clinical-pathological parameters was studied in a series of 54 patients with SNSCC. RESULTS: Loss of PTEN expression was observed in 33/54 cases (61%) and pAKT, mTOR and pS6 pre-expression was observed in 19/54 cases (35%), 8/54 cases (15%), and 47/54 cases (87%), respectively. Loss of PTEN expression was related to intracranial invasion and development of regional metastases (p=0.005). Overexpression of pS6 was associated with a decrease in survival (p=0.008), presence of local recurrences (p=0.055), and worsening of overall prognosis (p=0.007). No significant relationships were observed between pAKT and mTOR expression and the clinicopathological parameters studied. CONCLUSIONS: Alterations in the expression of EGFR/PI3K/pAKT/mTOR/pS6 pathway components are common in a subgroup of SNSCC. This study reveals that the absence of pS6 overexpression is associated with better clinical outcomes. Therefore, pS6 expression could be considered as an unfavourable prognostic marker.

Genomic profiling of intestinal-type sinonasal adenocarcinoma reveals subgroups of patients with distinct clinical outcomes.

BACKGROUND: Patients with intestinal-type sinonasal adenocarcinoma (ITAC) have an unfavorable prognosis and new therapeutic approaches are needed to improve clinical management. METHODS: Genetic analysis of 96 ITACs was performed by microarray comparative genomic hybridization and immunohistochemistry and correlated to previously obtained mutation, methylation, and protein expression data, and with pathological characteristics and clinical outcome. RESULTS: Seven copy number alterations (CNAs) were significantly associated with unfavorable clinical outcome: gains at 1q22-23, 3q28-29, 6p22, and 13q31-33, and losses at 4p15-16, 4q32-35, and 10q24. Unsupervised cluster analysis resulted in 5 subgroups of ITAC with significantly distinct genetic signatures and clinical outcomes, independently of disease stage or histological subtype. CONCLUSION: These data may guide studies to identify driver genes and signaling pathways involved in ITAC. In addition, the subclassification of genetic subgroups of patients with distinct clinical behavior can aid therapeutic decision making and may ultimately lead to personalized therapy with targeted inhibitors.

Genetic profiling of poorly differentiated sinonasal tumours.

The sinonasal cavities harbour a variety of rare tumour types. Many carry a poor prognosis while therapeutic options are limited. Histopathological classification can be difficult, especially for poorly differentiated tumours such as olfactory neuroblastoma (ONB), sinonasal neuroendocrine carcinoma (SNEC) and sinonasal undifferentiated carcinoma (SNUC). We analysed Affymetrix OncoScan genome-wide copy number profiles of these three tumour types, both as originally diagnosed and as regrouped by their cytokeratin (Ck) and neuroendocrine (Ne) expression pattern, aiming to find a relation between phenotype and genotype. According to the original histopathological classification our series consisted of 24 ONB, 11 SNEC and 19 SNUC, while immunohistochemistry indicated 11 Ck-Ne+/ONB, 18 Ck+Ne+/SNEC, 24 Ck+Ne-/SNUC, and 1 Ck-Ne-/unclassified. As originally diagnosed, the three tumour types showed similar copy number profiles. However, when regrouped by Ck/Ne immunostaining we found a distinct set of gains and losses; Ck-Ne+/ONB harboured few and predominantly whole chromosomes abnormalities, Ck+Ne+/SNEC carried both gains and losses in high frequency, and Ck+Ne-/SNUC showed mostly gains. In addition, each tumour carried a number of unique chromosomal deletions. Genome-wide copy number profiling supports the value of immunohistochemical CkNe staining of ONB, SNEC and SNUC for tumour classification, which is important for prognosis and therapeutic decision-making.

Programmed death ligand-1 expression as immunotherapeutic target in sinonasal cancer.

BACKGROUND: Sinonasal cancer carries a poor prognosis, especially in recurrent stages, and it is a disease with very limited treatment options. METHODS: The expression of programmed death ligand-1 (PD-L1) as a marker for immunotherapy was evaluated in 53 sinonasal squamous cell carcinoma (SCC) and 126 intestinal-type adenocarcinoma (ITAC) samples. Results were correlated to clinicopathological characteristics and follow-up data. RESULTS: Membranous PD-L1 staining of tumor cells was observed in 34% (18/53) of the sinonasal SCC samples and in 17% (22/126) of the ITAC samples. The PD-L1 positivity on infiltrating immune cells occurred in 45% (24/53) of the sinonasal SCC samples and in 33% (41/126) of the ITAC samples. Expression of PD-L1 showed no correlation to clinicopathological parameters and was not an independent risk factor for survival. CONCLUSION: The PD-L1 positivity does not seem to have prognostic value. However, a proportion of patients with sinonasal SCC and ITAC may benefit from therapy with immune checkpoint inhibitors that recently have been approved for clinical application in head and neck cancer.

Factors Secreted by Cancer-Associated Fibroblasts that Sustain Cancer Stem Properties in Head and Neck Squamous Carcinoma Cells as Potential Therapeutic Targets.

This study investigates for the first time the crosstalk between stromal fibroblasts and cancer stem cell (CSC) biology in head and neck squamous cell carcinomas (HNSCC), with the ultimate goal of identifying effective therapeutic targets. The effects of conditioned media from cancer-associated fibroblasts (CAFs) and normal fibroblasts (NFs) on the CSC phenotype were assessed by combining functional and expression analyses in HNSCC-derived cell lines. Further characterization of CAFs and NFs secretomes by mass spectrometry was followed by pharmacologic target inhibition. We demonstrate that factors secreted by CAFs but not NFs, in the absence of serum/supplements, robustly increased anchorage-independent growth, tumorsphere formation, and CSC-marker expression. Modulators of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), and platelet-derived growth factor receptor (PDGFR) activity were identified as paracrine cytokines/factors differentially secreted between CAFs and NFs, in a mass spectrometry analysis. Furthermore, pharmacologic inhibition of EGFR, IGFR, and PDGFR significantly reduced CAF-induced tumorsphere formation and anchorage-independent growth suggesting a role of these receptor tyrosine kinases in sustaining the CSC phenotype. These findings provide novel insights into tumor stroma⁻CSC communication, and potential therapeutic targets to effectively block the CAF-enhanced CSC niche signaling circuit.

Absence of chromosomal translocations and protein expression of ALK in sinonasal adenocarcinomas. / Ausencia de translocaciones cromosómicas y de expresión proteica de ALK en los adenocarcinomas nasosinusales.

INTRODUCTION: Chromosomal translocations at 2p23 cause overexpression of anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase involved in signalling pathways that regulate cell proliferation. This translocation occurs in 5% of lung adenocarcinoma and has been demonstrated to be useful as a therapeutic target for crizotinib. sinonasal adenocarcinomas (SNAC) are histologically similar to lung adenocarcinomas; the aim of this study was to evaluate the presence of ALK alterations in SNAC. METHOD: Break-apart fluorescent in-situ hybridization was used to analyse the presence of ALK translocations in 96 tumour samples. In addition, ALK protein expression was studied by immunohistochemistry. RESULTS: The samples of SNAC did not show ALK translocation. Moreover, ALK protein expression was absent in all cases. CONCLUSIONS: These results suggest that ALK is not involved in SNAC.

Gene Methylation Profiling in Sinonasal Adenocarcinoma and Squamous Cell Carcinoma.

OBJECTIVE: To identify epigenetic events in intestinal-type sinonasal adenocarcinoma (ITAC) and sinonasal squamous cell carcinoma (SNSCC) and to evaluate their relation to clinicopathologic features and follow-up data. STUDY DESIGN: Retrospective study. SETTING: Academic research hospital. SUBJECTS AND METHODS: The methylation status of 23 genes in 50 ITACs and 32 SNSCCs was analyzed by methylation-specific multiplex ligation-dependent probe amplification and its relation to clinicopathologic features and follow-up data. RESULTS: Gene methylation was observed in 50% of all tumors. Recurrent methylated genes in SNSCC were RASSF1 and CDH13 (for both, 6 of 32 cases), CHFR (4 of 32 cases), and TIMP3 (2 of 32 cases). None of these genes showed significant correlation to clinicopathologic features or overall survival. In ITAC, recurrent methylated genes were CDH13 (18 of 50 cases), ESR1 (13 of 50 cases), APC (7 of 50 cases), TIMP3 (5 of 50 cases), CASP8 (3 of 50 cases), and HIC1 and RASSF1 (for both, 2 of 50 cases). Papillary and colonic ITAC subtypes carried a mean of 1.26 gene methylations per tumor versus 0.63 in solid and mucinous subtypes. Methylation of TIMP3 was associated with a significantly worse survival in ITAC patients. CONCLUSION: ITAC carries a higher number and a different profile of gene methylations as compared with SNSCC. Gene methylation plays a greater role in papillary and colonic ITAC subtypes, which may indicate a different tumorigenic pathway for these ITAC subtypes. These findings could be used as prognosticators and may have implications for future individualized therapies based on epigenetic changes.

EC-70124, a Novel Glycosylated Indolocarbazole Multikinase Inhibitor, Reverts Tumorigenic and Stem Cell Properties in Prostate Cancer by Inhibiting STAT3 and NF-κB.

Cancer stem cells (CSC) contribute to disease progression and treatment failure in prostate cancer because of their intrinsic resistance to current therapies. The transcription factors NF-κB and STAT3 are frequently activated in advanced prostate cancer and sustain expansion of prostate CSCs. EC-70124 is a novel chimeric indolocarbazole compound generated by metabolic engineering of the biosynthetic pathways of glycosylated indolocarbazoles, such as staurosporine and rebeccamycin. In vitro kinome analyses revealed that EC-70124 acted as a multikinase inhibitor with potent activity against IKKß and JAK2. In this study, we show that EC-70124 blocked concomitantly NF-κB and STAT3 in prostate cancer cells and particularly prostate CSCs, which exhibited overactivation of these transcription factors. Phosphorylation of IkB and STAT3 (Tyr705), the immediate targets of IKKß and JAK2, respectively, was rapidly inhibited in vitro by EC-70124 at concentrations that were well below plasma levels in mice. Furthermore, the drug blocked activation of NF-κB and STAT3 reporters and suppressed transcription of their target genes. Treatment with EC-70124 impaired proliferation and colony formation in vitro and delayed development of prostate tumor xenografts. Notably, EC-70124 had profound effects on the prostate CSC subpopulation both in vitro and in vivo Thus, EC-70124 is a potent inhibitor of the NF-κB and STAT3 signaling pathways and blocked tumor growth and maintenance of prostate CSCs. EC-70124 may provide the basis for developing new therapeutic strategies that combine agents directed to the CSC component and the bulk tumor cell population for treatment of advanced prostate cancer. Mol Cancer Ther; 15(5); 806-18. ©2016 AACR.

DNA aneuploidy-specific therapy for head and neck squamous cell carcinoma.

BACKGROUND: Patients with head and neck squamous cell carcinoma (HNSCC) have an unfavorable prognosis, with a 5-year survival rate of approximately 40%. Genetic analyses have revealed that the majority of HNSCCs carry complex, aneuploid karyotypes, showing numerical and structural chromosomal imbalances. New compounds are being developed that target chromosomal instability in general, specifically affecting cells with aneuploid karyotypes. METHODS: Two such compounds, 5-aminoimidazole-4-carboxamide riboside (AICAR) and 17-allylamino-17-demethoxygeldanamycin (17-AAG), were tested using a panel of stable diploid and unstable aneuploid HNSCC cell lines, and short-term cultures of normal keratinocytes as control. RESULTS: A significant growth inhibitory effect by both compounds was observed in the aneuploid compared to diploid HNSCC cell lines and to the normal keratinocytes. This effect was independent from the TP53 mutation status. Combination treatment with AICAR and 17-AAG demonstrated the strongest inhibition. CONCLUSION: Aneuploidy-targeted therapy may be a viable addition to the treatment options for HNSCC.

Establishment and characterization of an orthotopic sinonasal squamous cell carcinoma mouse model.

BACKGROUND: Despite therapeutic improvements, patients with sinonasal squamous cell carcinoma (SCC) still face an unfavorable prognosis and there is great need for alternative treatments. METHODS: SCCNC4 cells, originally derived from a T2N1M0 primary and untreated sinonasal SCC, were inoculated in the maxillary sinus of immunodeficient mice. Histology, invasive behavior, and genetic features were evaluated and compared with the original primary tumor. RESULTS: The mice developed tumors that invaded bone, surrounding tissues, and brain, showing the same poor differentiation as the original primary tumor. Genetic analysis revealed an almost identical pattern of copy number alterations, except for the deletion and loss of expression of the genes CDKN2A and PTEN. CONCLUSION: This article shows the feasibility of an orthotopic mouse model of SCC of the maxillary sinus. Completed by genome-wide genetic profiling data, this model will be useful for preclinical testing of specific gene-targeted anticancer drugs.

Establishment and genetic characterization of six unique tumor cell lines as preclinical models for sinonasal squamous cell carcinoma.

Sinonasal squamous cell carcinomas (SCC) are rare tumors, etiologically related to occupational exposure to wood and leather dust. In spite of surgical and radiotherapeutic advances, the 5 year survival is still 30-50%. Therefore, alternative treatment options are needed. We report the establishment and characterization of six unique human sinonasal SCC cell lines, named SCCNC1, 2, 4, 5, 6 and 7. In vitro growth and invasion characteristics were evaluated and genetic profiles were compared to those of the original primary tumors. The population doubling times ranged from 21 to 34 hours. Cell lines SCCNC2 and 7 were highly invasive in matrigel. Five cell lines carried a high number of copy number alterations, including amplifications and homozygous deletions, while one showed only three abnormalities. Sequence analysis revealed three cell lines with TP53 mutation and none with KRAS or BRAF. Overexpression of p53 was observed in five, and of EGFR in four cell lines. None of the cell lines showed strong immunopositivity of p16 or presence of human papilloma virus. In conclusion, we have created six new cell lines that are clinically and genetically representative of sinonasal SCC and that will be a useful tool for the preclinical testing of new therapeutic agents.

Molecular characterisation of sinonasal carcinomas and their clinical implications.

Sinonasal carcinomas are rare tumours with an unfavourable prognosis whose management is difficult and complex, leading to high morbidity and mortality despite improvements in the field of surgery and radiotherapy. An elevated number of these tumours can be attributed to occupational exposure. In comparison with other head and neck malignancies, studies of molecular changes in these tumours are infrequent. This review was focused on findings about the epidemiology and molecular and phenotypic characterisation of sinonasal carcinomas, which can potentially be useful for diagnosis and treatment. The increasing knowledge about the molecular biology that underlies their carcinogenesis may help to identify precursor lesions, prognostic markers and markers that predict chemoradiotherapy response and, finally, to identify potential molecular targets that will expand treatment options.

EGFR status and KRAS/BRAF mutations in intestinal-type sinonasal adenocarcinomas.

BACKGROUND: Intestinal-type sinonasal adenocarcinoma (ITAC) is a rare tumour that is etiologically related to professional exposure to wood dust and exhibits a poor prognosis. Treatment alternatives to surgery and radiotherapy are needed and may be found in anti-EGFR agents. EGFR gene copy number gains and KRAS/BRAF mutations have been reported to act as positive and negative predictors, respectively, of therapeutic response to EGFR targeted therapies in colorectal adenocarcinoma, a tumour type claimed to be genetically similar to ITAC. Therefore, the aim of this study was to evaluate the occurrence and consequence of EGFR alterations and KRAS and BRAF mutations in a large series of ITAC. METHODS: EGFR protein expression was studied in 98 paraffin embedded tissue samples, organized in a tissue microarray. Gene copy number analysis was performed by FISH using the same tissue microarray, complemented by microarray CGH and MLPA analysis on DNA extracted from 65 fresh frozen tissues. Mutations in EGFR, KRAS and BRAF were analysed by direct sequencing on 65 fresh frozen tissues. RESULTS: EGFR gene copy number gains were observed in 45 %, and protein over-expression in 21 % of the cases. No mutations were found in EGFR or BRAF, while KRAS mutations were present in 12 % of the cases. Neither protein overexpression nor gene copy number gain correlated to histological subtype, tumour stage or clinical follow-up. CONCLUSION: In the largest series of ITAC published to date, and using a number of different techniques, EGFR alterations were frequently observed. Although apparently not useful as a prognostic factor, there may be a basis for investigating EGFR targeted therapies in this group of patients, especially because negative response predictors such as KRAS and BRAF mutations are infrequent or absent, respectively.

KRAS and BRAF mutations in sinonasal cancer.

OBJECTIVES: [corrected] Despite improvements in the field of surgery and radiotherapy, the overall prognosis of sinonasal carcinomas is poor, mainly due to the difficulty to resect the tumour completely in this anatomically complex region. Therefore, there is great need for alternative treatments. Knowledge of the KRAS and BRAF mutational status would become clinically important with regard to the possible use of anti-EGFR therapies. MATERIAL AND METHODS: DNA was extracted from paraffin embedded tumour samples from 57 cases of sinonasal squamous cell carcinoma (SNSCC) and from fresh frozen tumour samples from 58 cases of intestinal-type sinonasal adenocarcinoma (ITAC). Point mutations were analysed for KRAS exon 2 (codons 12 and 13) and BRAF (exon 15, V600E) by direct sequencing. RESULTS: Neither KRAS nor BRAF showed any mutations in the SNSCC, whereas 7/58 (12%) ITAC harboured KRAS mutations and no BRAF mutations. All seven cases with KRAS mutation concerned well-differentiated and less aggressive (papillary and colonic type) ITAC, all patients being woodworkers and 4/7 tobacco smokers. CONCLUSION: Neither of SNSCCs carried mutations in KRAS and BRAF and a low frequency of KRAS mutation was found in ITAC. This suggests that KRAS and BRAF mutations play a limited role in the development of sinonasal cancer and that mutation analysis is not useful as a screening test for sensitivity to anti-EGFR therapy in sinonasal cancer.

Genomic profiling of sinonasal squamous cell carcinoma.

BACKGROUND: Sinonasal squamous cell carcinomas (SCCs) are rare tumors with no etiologic link to tobacco and alcohol, as opposed to other SCCs of the head and neck (HNSCC). Little is known about the genetic changes in sinonasal SCC. METHODS: DNA copy number changes of sinonasal SCC were analyzed by multiplex ligation-dependent probe amplification (MLPA) and microarray comparative genomic hybridization (maCGH), and results were related to clinicopathologic features. RESULTS: Copy number losses most frequently included genes at 9p21, 13q14, 17p13, 17q21, and 18q11. Frequent gains were observed on 8q24, 11q13, 17q12, 19p13, and 20q11-q13. CONCLUSION: The genomic profile of sinonasal SCC showed a number of chromosomal regions with copy number changes similar to those known in HNSCC, in spite of the differences in etiology.

Establishment and genetic characterization of an immortal tumor cell line derived from intestinal-type sinonasal adenocarcinoma.

BACKGROUND: Intestinal-type sinonasal adenocarcinoma (ITAC) is a rare tumor etiologically related to professional exposure to wood dust. The overall prognosis is poor, mainly due to the difficulty to resect the tumor completely in this anatomically complex region. Therefore, there is great need for alternative treatments. However, the lack of a good tumor model system for ITAC has hampered the development and testing of new therapeutic agents. Here, we report the establishment and characterization of the first human ITAC cell line named ITAC-3. METHODS: The cell line was initiated from small explants of a T4bN0M0 colonic type ITAC from the ethmoid sinus. Growth and invasion parameters as well as genetic characteristics were analyzed. RESULTS: The population doubling time was 18 h and the cell line was capable of invasion in matrigel. Chromosomal analysis showed a tetraploid karyotype with both numerical and structural aberrations. High resolution microarray CGH analysis identified many copy number alterations, including homozygous deletions. TP53 carried a mutation c.818G>T in exon eight concurring with a strong nuclear protein overexpression. Immunohistochemical analysis showed protein overexpression of EGFR and normal expression of ß-catenin and p16. CONCLUSION: This is the first report of the establishment of a cell line derived from a primary ITAC. The genomic profile of the cell line was the same as the primary tumor from which it was derived. This new cell line will be a useful tool for the development and testing of new therapeutic agents for this tumor type.

Relevance of germline mutation screening in both familial and sporadic head and neck paraganglioma for early diagnosis and clinical management.

BACKGROUND: Head and neck paraganglioma (PGL) are benign tumors that can cause important direct or surgery induced morbidity. Almost all familial and 11-29% of sporadic PGL are caused by inactivating germline mutations in succinate dehydrogenase (SDH) genes. Our aim was to screen for such mutations and to evaluate clinical parameters as predictors of germline mutation. METHODS: Seventy-four PGL patients were analyzed for germline mutations and large deletions in SDH genes, VHL and RET. Results were correlated to clinical characteristics including gender, age, tumor localization and multifocality. The surgical approach was evaluated in terms of tumor origin, sequelae and subsequent evolution. RESULTS: Mutations in SDHB and SDHD were identified in equal proportion in 13/13 (100%) of familial and in 15/61 (25%) of sporadic cases. Familiarity, age < or =50 years and male gender were predictors of any germline mutation, while multifocality and carotid/vagal localization were indicative of SDHD mutation in particular. CONCLUSION: In contrast to other series, this cohort of Spanish patients showed many SDHB mutations. Sporadic cases with germline mutation are frequent and underline the importance of mutational screening of all PGL patients, allowing the identification of relatives at risk and the early diagnosis of the disease, reducing or avoiding morbidity.