Differential expression of human telomerase catalytic subunit mRNA by in situ hybridization in pheochromocytomas

Potential Biomarkers of Metastasizing Paragangliomas and Pheochromocytomas

Paragangliomas and pheochromocytomas (PPGLs) are rare neuroendocrine tumors originating from paraganglionic tissue in many sites of the body. Most PPGLs are characterized by nonaggressive behavior but all of them have the potential to metastasize. PPGLs represent a great diagnostic dilemma as it is difficult to recognize tumors that are likely to be metastasizing; criteria of malignancy can be found both in benign and metastatic forms. This review aims to analyze the current knowledge of the nature of metastasizing PPGLs paying particular attention to head and neck paragangliomas (HNPGLs). Potential predictors of the malignancy risk for PPGLs were summarized and discussed. These data may also help in the development of diagnostic and prognostic strategies, as well as in the identification of novel potential therapeutic targets for patients with PPGLs.

Telomerase Activation and ATRX Mutations Are Independent Risk Factors for Metastatic Pheochromocytoma and Paraganglioma

PURPOSE

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors. Whereas most PPGLs are benign, up to 20% may become metastatic with SDHB- and FH-mutated tumors showing the higher risk. We aimed at determining the contribution of immortalization mechanisms to metastatic progression.Experimental Design: Immortalization mechanisms were investigated in 200 tumors. To identify telomerase (+) tumors, we analyzed genomic alterations leading to transcriptional activation of TERT comprising promoter mutations, hypermethylation and gain copy number. To identify tumors that activated the alternative lengthening of telomere (ALT) mechanism, we combined analyses of telomere length by slot blot, telomere heterogeneity by telomere FISH, and ATRX mutations by next-generation sequencing. Univariate/multivariate and metastasis-free survival (MFS) and overall survival (OS) analyses were carried out for assessment of risk factors and clinical outcomes.

RESULTS

Only 37 of 200 (18.5%) tumors achieved immortalization. Telomerase activation occurred in 12 metastatic tumors and was prevalent in SDHB-mutated paragangliomas (P = 2.42e-09). ALT features were present in 25 tumors, mostly pheochromocytomas, regardless of metastatic status or molecular group (P = 0.169), yet ATRX mutations were found preferentially in SDHB/FH-mutated metastatic tumors (P = 0.0014). Telomerase activation and ATRX mutations were independent factors of poor prognosis: MFS (hazard ratio, 48.2 and 33.1; P = 6.50E-07 and 1.90E-07, respectively); OS (hazard ratio, 97.4 and 44.1; P = 4.30E-03 and 2.00E-03, respectively) and were associated with worse MFS and OS (log-rank tests P < 0.0001).

CONCLUSIONS

Assessment of telomerase activation and ATRX mutations could be used to identify metastatic PPGLs, particularly in tumors at high risk of progression.

Analyzing adjuvant radiotherapy suggests a non monotonic radio-sensitivity over tumor volumes

BACKGROUND

Adjuvant Radiotherapy (RT) after surgical removal of tumors proved beneficial in long-term tumor control and treatment planning. For many years, it has been well concluded that radio-sensitivities of tumors upon radiotherapy decrease according to the sizes of tumors and RT models based on Poisson statistics have been used extensively to validate clinical data.

RESULTS

We found that Poisson statistics on RT is actually derived from bacterial cells despite of many validations from clinical data. However cancerous cells do have abnormal cellular communications and use chemical messengers to signal both surrounding normal and cancerous cells to develop new blood vessels and to invade, to metastasis and to overcome intercellular spatial confinements in general. We therefore investigated the cell killing effects on adjuvant RT and found that radio-sensitivity is actually not a monotonic function of volume as it was believed before. We present detailed analysis and explanation to justify above statement. Based on EUD, we present an equivalent radio-sensitivity model.

CONCLUSION

We conclude that radio sensitivity is a sophisticated function over tumor volumes, since tumor responses upon radio therapy also depend on cellular communications.

Prognostic indicators of malignancy in adrenal pheochromocytomas: clinical, histopathologic, and cell cycle/apoptosis gene expression analysis

BACKGROUND

Pheochromocytomas are malignant in approximately 10% of patients. The histologic differentiation between benign and malignant tumors is difficult, the latter diagnosed by the presence of metastatic disease or recurrence.

AIM

To determine if postoperative histologic evaluation using the previously proposed Pheochromocytoma of the Adrenal Gland Scaled Score (PASS) and cell cycle/apoptosis markers can predict patients at risk for recurrence.

METHODS

Using the Memorial Sloan-Kettering Cancer Center adrenal database, we identified 48 patients with 51 resected pheochromocytomas (1987-2006). A senior endocrine pathologist, blinded to clinical outcome, reviewed the histopathologic characteristics of all cases using the PASS system. This pheochromocytoma scoring system is based on the presence of 12 different histologic parameters, including tumor necrosis, mitotic rate, tumor cell spindling, and the presence of large cell nests. In addition, we constructed a tissue microarray of all 5 malignant tumors and 41 of the benign tumors. By immunostaining of the tissue microarray, we assessed the expression of 7 different cell cycle/apoptosis-related genes (p53, Ki-67, Bcl-2, mdm-2, cyclin D1, p21, and p27).

RESULTS

Forty-three patients had a benign clinical course while 5 patients harbored a clinically malignant pheochromocytoma. Tumor necrosis (focal or confluent) was a particularly powerful indicator of malignancy present in 4 of 5 patients (80%) with malignant tumors, but only in 3 of 42 cases (7%) with benign neoplasms (P = .0009). The presence of a high mitotic rate (>3/10 high power fields) and tumor cell spindling significantly correlated with malignancy (P = .026 and .041, respectively). High cellularity was more often present in the malignant lesions (P = .050). There was a highly significant difference in PASS scores between benign and malignant cases (P = .0003). All malignant pheochromocytomas had a PASS score >/=6, well above the previously proposed >/=4 cutoff value. Two of the 4 patients testing positive for Ki-67 (>2% nuclear staining) had a clinically malignant course while only 3 (7%) of the 41 cases with lower Ki-67 positivity rate behaved in a malignant fashion (P = .055). Ki-67-positive tumor had a significantly higher chance of harboring tumor necrosis than Ki-67-negative neoplasms (P < .01). There was no difference in staining between benign and malignant pheochromocytomas using p53, Bcl-2, mdm-2, cyclin D1, p21, and p27.

CONCLUSIONS

(1) A PASS score of <4 predicted benign pheochromocytomas. (2) All malignant pheochromocytomas had a PASS score >/=6, which was significantly higher compared with the benign lesions. Patients with a PASS score >/=4 should be followed closely for recurrence. (3) p53, Bcl-2, mdm-2, cyclin D1, p21, and p27 appear to have no role in predicting the behavior of pheochromocytomas. Ki-67 may help identify those neoplasms at risk for recurrence by prompting the pathologist to look aggressively for adverse histologic features.