Malignant Pheochromocytoma in a Population-Based Study: Survival and Clinical Results

Primary tumour resection for synchronously metastatic phaeochromocytoma and paraganglioma: A population-based study

CONTEXT

Until recently, there are few effective treatment options for patients with synchronous metastatic phaeochromocytoma (PHEO) and paraganglioma (PGL). Surgical resection may improve the survival outcomes of these patients.

OBJECTIVE

To assess the role of surgical resection of the primary tumour in patients with synchronous metastatic PHEO and PGL.

DESIGN

Retrospective analysis of patients with synchronous metastatic PHEO/PGL using the Surveillance, Epidemiology, and End Results database (1988-2016).

PATIENTS

Patients with synchronous metastatic PHEO/PGL who underwent primary tumour resection.

MEASUREMENTS

Overall survival and Cox regression analyses.

RESULTS

A total of 99 patients with metastatic PHEO and 127 metastatic PGL patients were identified from the SEER database. Compared to metastatic PHEO, metastatic PGL patients had a better overall survival (5-year survival rate: 33.3% vs. 49.0%, p = .001). In metastatic PHEO patients, 53 (53.5%) patients underwent surgery for primary site. Surgically treated patients had an improved survival compared to non-surgery patients (5-year survival rate: 50.9% vs. 29.6%, p = .017). Among metastatic PGL patients, primary tumour resection was performed in 74 (58.3%) patients and had no significant effect on the survival of metastatic PGL. In sub-analyses, surgery only conferred a survival benefit in patients with primary tumours originated from aortic/carotid bodies, rather than other sites or abdominal tumours.

CONCLUSION

Our findings suggest that primary tumour resection is associated with improved survival in patients with synchronous metastatic PHEO and those with PGL diseases located in aortic/carotid bodies. In addition, PHEO and PGL should be treated as two distinct clinical entities.

MYO5B mutations in pheochromocytoma/paraganglioma promote cancer progression

Identification of additional cancer-associated genes and secondary mutations driving the metastatic progression in pheochromocytoma and paraganglioma (PPGL) is important for subtyping, and may provide optimization of therapeutic regimens. We recently reported novel recurrent nonsynonymous mutations in the MYO5B gene in metastatic PPGL. Here, we explored the functional impact of these MYO5B mutations, and analyzed MYO5B expression in primary PPGL tumor cases in relation to mutation status. Immunohistochemistry and mRNA expression analysis in 30 PPGL tumors revealed an increased MYO5B expression in metastatic compared to non-metastatic cases. In addition, subcellular localization of MYO5B protein was altered from cytoplasmic to membranous in some metastatic tumors, and the strongest and most abnormal expression pattern was observed in a paraganglioma harboring a somatic MYO5B:p.G1611S mutation. In addition to five previously discovered MYO5B mutations, the present study of 30 PPGL (8 previous and 22 new samples) also revealed two, and hence recurrent, mutations in the gene paralog MYO5A. The three MYO5B missense mutations with the highest prediction scores (p.L587P, p.G1611S and p.R1641C) were selected and functionally validated using site directed mutagenesis and stable transfection into human neuroblastoma cells (SK-N-AS) and embryonic kidney cells (HEK293). In vitro analysis showed a significant increased proliferation rate in all three MYO5B mutated clones. The two somatically derived mutations, p.L587P and p.G1611S, were also found to increase the migration rate. Expression analysis of MYO5B mutants compared to wild type clones, demonstrated a significant enrichment of genes involved in migration, proliferation, cell adhesion, glucose metabolism, and cellular homeostasis. Our study validates the functional role of novel MYO5B mutations in proliferation and migration, and suggest the MYO5-pathway to be involved in the malignant progression in some PPGL tumors.

Up to 25% of pheochromocytoma/paraganglioma (PPGL) cases develop metastatic disease with poor outcome and few treatment options. The disease mechanism is not fully understood, and to date there are no reliable markers to predict malignancy. We have recently discovered novel missense mutations in the non-conventional myosin 5 gene (MYO5B), an endosomal transport protein, which we now show enhances progression and migration in PPGLs. MYO5B mutations were preferentially found in patients with metastatic disease and SDH deficiency (germline SDHB-mutations). Abolished SDH activity result in a metabolic switch to aerobic glycolysis requiring increased glucose consumption. Since the MYO5B mutations were found to drive progression through downstream up-regulation of glucose metabolism genes, e.g. glucagon, we hypothesize that these mutations may fuel the pseudohypoxic state by altering glucose uptake in cancer cells. Our result is the first to link the myosin 5 genes to PPGL tumorigenesis. Further, it shows that the tumor progression route in PPGL is complex, with contribution from several genetic factors. An increasing number of studies show dysregulation and importance of the MYO5-proteins in cancer, but little is still known about the precise role and mechanism of mutations, hence more research in this area is needed.

The presence of SDHB mutations should modify surgical indications for carotid body paragangliomas

OBJECTIVE

The aim of this study was to determine whether the genetic background of the disease should be incorporated into treatment decision making.

BACKGROUND

Carotid body paragangliomas are rare tumors that often affect patients with genetic mutations of the succinate dehydrogenase complex (SDHx). Despite growing evidence that germ line genetic mutations alter the aggressiveness of paragangliomas, treatment decisions are currently based only on clinical symptoms and tumor size in patients with carotid body paragangliomas.

METHODS

Retrospective analysis of 34 patients with carotid body paragangliomas who underwent genetic testing and surgical treatment. Recurrence was defined by the return of locoregional disease and/or development of distant metastases. Clinical characteristics and genetic testing results were analyzed as predictors of patient outcomes.

RESULTS

Thirty-four patients underwent 41 primary carotid body paraganglioma resections (median follow-up time of 42 months, range: 1-293). Overall survival was 91.2%. Twelve patients had germ line mutations in SDHB, 17 in SDHD, and 5 carried no known mutation. Surgical resection of larger tumors was associated with higher operative complications (odds ratio: 5.4, P = 0.05). Tumor size at resection was significantly smaller in patients with SDHB mutations than in patients with non-SDHB mutations (2.1 vs 3.3 cm, P = 0.02). Patients with a mutation in the SDHB gene also had significantly worse disease-free survival compared with patients without an SDHB gene mutation (P = 0.03).

CONCLUSIONS

Mutations in the SDHB gene are associated with worse disease-free survival after resection in patients with carotid body paragangliomas despite earlier intervention. This suggests that a more aggressive surgical approach is warranted in patients with SDHB mutations.

Pheochromocytoma management, outcomes and the role of cortical preservation

OBJECTIVES

To evaluate the management and outcome of children with pheochromocytoma and determine the role of cortex preservation in cases of bilateral disease.

METHODS

Retrospective review of children, below 12 y of age, with pheochromocytoma managed between November 2003 and December 2012 was done.

RESULTS

Twelve patients, nine boys and three girls with median age 9 y were enrolled. Eleven (92 %) had adrenal tumors and in one it was extra-adrenal. Five (42 %) had bilateral disease. Ten presented with hypertension, one with headache and one with abdominal pain and fever. All were stabilized pre-operatively with alpha and beta blockers and volume expansion. Six children with unilateral disease underwent total adrenalectomy. Out of five with bilateral disease, one child underwent bilateral total adrenalectomy and was later started on hormone replacement. Remaining four underwent total adrenalectomy on one side and partial on the other side. Post-operatively all became symptom free and normotensive and were off medications within 1 mo. Two children developed recurrence 1 mo post-operatively, one with an initial unilateral pheochromocytoma and one with paraganglionoma. At the last follow up, 10 out of 12(83 %) were disease free while two with recurrence are still awaiting surgery.

CONCLUSIONS

Surgical resection of pheochromocytoma is effective treatment to achieve cure and prolong survival. Cortex preservation should be done in bilateral disease as risk of recurrence in such cases seems to be of lesser significance as compared to the morbidity and mortality of adrenal insufficiency and consequent lifelong hormone replacement.

Pheochromocytoma and paraganglioma: an endocrine society clinical practice guideline

OBJECTIVE

The aim was to formulate clinical practice guidelines for pheochromocytoma and paraganglioma (PPGL).

PARTICIPANTS

The Task Force included a chair selected by the Endocrine Society Clinical Guidelines Subcommittee (CGS), seven experts in the field, and a methodologist. The authors received no corporate funding or remuneration.

EVIDENCE

This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. The Task Force reviewed primary evidence and commissioned two additional systematic reviews.

CONSENSUS PROCESS

One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of the Endocrine Society, European Society of Endocrinology, and Americal Association for Clinical Chemistry reviewed drafts of the guidelines.

CONCLUSIONS

The Task Force recommends that initial biochemical testing for PPGLs should include measurements of plasma free or urinary fractionated metanephrines. Consideration should be given to preanalytical factors leading to false-positive or false-negative results. All positive results require follow-up. Computed tomography is suggested for initial imaging, but magnetic resonance is a better option in patients with metastatic disease or when radiation exposure must be limited. (123)I-metaiodobenzylguanidine scintigraphy is a useful imaging modality for metastatic PPGLs. We recommend consideration of genetic testing in all patients, with testing by accredited laboratories. Patients with paraganglioma should be tested for SDHx mutations, and those with metastatic disease for SDHB mutations. All patients with functional PPGLs should undergo preoperative blockade to prevent perioperative complications. Preparation should include a high-sodium diet and fluid intake to prevent postoperative hypotension. We recommend minimally invasive adrenalectomy for most pheochromocytomas with open resection for most paragangliomas. Partial adrenalectomy is an option for selected patients. Lifelong follow-up is suggested to detect recurrent or metastatic disease. We suggest personalized management with evaluation and treatment by multidisciplinary teams with appropriate expertise to ensure favorable outcomes.

Response after surgical resection of metastatic pheochromocytoma and paraganglioma: can postoperative biochemical remission be predicted?

BACKGROUND

Aggressive surgical resection with intent to cure and surgical debulking procedures are commonly recommended in patients with metastatic pheochromocytoma and paraganglioma. To date there are no data on operative outcomes of patients after surgical resection of metastatic pheochromocytoma and paraganglioma to determine if such an approach is appropriate and what factors may be associated with a favorable outcome.

STUDY DESIGN

We performed a retrospective analysis of 30 patients with metastatic pheochromocytoma/paraganglioma who underwent surgical treatment. Clinical characteristics and genetic factors were analyzed as predictors of biochemical response to surgery.

RESULTS

Thirty patients underwent a total of 42 operations, with a median follow-up time of 24 months (range 1 to 114 months). Complete disease resection (R0/R1) was achieved in 18 (42.9%) cases; 24 cases (57.1%) were debulking (R2) procedures without intent to cure. Complete biochemical remission was achieved in 10 (23.8%) cases and partial biochemical response was achieved in 23 (54.8%) cases. Patients with disease confined to the abdomen were more likely to achieve and maintain a biochemical response postoperatively than those with extra-abdominal disease (p = 0.0003). Debulking operations were significantly less likely to achieve or maintain biochemical palliation, with only 1 patient maintaining a biochemical response 12 months postoperatively (p < 0.0001). Patients were less likely to obtain pharmacologic independence after debulking (p = 0.0003), with only 2 (8.3%) not requiring pharmacotherapy 6 months after the intervention. Factors not associated with biochemical response to surgery include sex, family history, SDHB mutation status, systemic therapy, and preoperative biochemical profile.

CONCLUSIONS

Depending on the extent of disease, patients with metastatic pheochromocytoma/paraganglioma can benefit from aggressive operative intervention and resection with intent to cure. Debulking procedures are unlikely to achieve clinically significant biochemical response, with any biochemical response achieved being very short-lived.

Acquired hypermethylation of the P16INK4A promoter in abdominal paraganglioma: relation to adverse tumor phenotype and predisposing mutation

Recurrent alterations in promoter methylation of tumor suppressor genes (TSGs) and LINE1 (L1RE1) repeat elements were previously reported in pheochromocytoma and abdominal paraganglioma. This study was undertaken to explore CpG methylation abnormalities in an extended tumor panel and assess possible relationships between metastatic disease and mutation status. CpG methylation was quantified by bisulfite pyrosequencing for selected TSG promoters and LINE1 repeats. Methylation indices above normal reference were observed for DCR2 (TNFRSF10D), CDH1, P16 (CDKN2A), RARB, and RASSF1A. Z-scores for overall TSG, and individual TSG methylation levels, but not LINE1, were significantly correlated with metastatic disease, paraganglioma, disease predisposition, or outcome. Most strikingly, P16 hypermethylation was strongly associated with SDHB mutation as opposed to RET/MEN2, VHL/VHL, or NF1-related disease. Parallel analyses of constitutional, tumor, and metastasis DNA implicate an order of events where constitutional SDHB mutations are followed by TSG hypermethylation and 1p loss in primary tumors, later transferred to metastatic tissue. In the combined material, P16 hypermethylation was prevalent in SDHB-mutated samples and was associated with short disease-related survival. The findings verify the previously reported importance of P16 and other TSG hypermethylation in an independent tumor series. Furthermore, a constitutional SDHB mutation is proposed to predispose for an epigenetic tumor phenotype occurring before the emanation of clinically recognized malignancy.

Preclinical assessment of strategies for enhancement of metaiodobenzylguanidine therapy of neuroendocrine tumors

By virtue of its high affinity for the norepinephrine transporter (NET), [(131)I]metaiodobenzylguanidine ([(131)I]MIBG) has been used for the therapy of tumors of neuroectodermal origin for more than 25 years. Although not yet universally adopted, [(131)I]MIBG targeted radiotherapy remains a highly promising means of management of neuroblastoma, pheochromocytoma, and carcinoids. Appreciation of the mode of conveyance of [(131)I]MIBG into malignant cells and of factors that influence the activity of the uptake mechanism has indicated a variety of means of increasing the effectiveness of this type of treatment. Studies in model systems revealed that radiolabeling of MIBG to high specific activity reduced the amount of cold competitor, thereby increasing tumor dose and minimizing pressor effects. Increased radiotoxicity to targeted tumors might also be achieved by the use of the α-particle emitter [(211)At]astatine rather than (131)I as radiolabel. Recently it has been demonstrated that potent cytotoxic bystander effects were induced by [(131)I]MIBG, [(123)I]MIBG, and [(211)At]meta-astatobenzylguanidine. Discovery of the structure of bystander factors could increase the therapeutic ratio achievable by MIBG targeted radiotherapy. [(131)I]MIBG combined with topotecan produced supra-additive cytotoxicity in vitro and tumor growth delay in vivo. The enhanced antitumor effect was consistent with a failure to repair DNA damage. Initial findings suggest that further enhancement of efficacy might be achieved by triple combination therapy with drugs that disrupt alternative tumor-specific pathways and synergize not only with [(131)I]MIBG abut also with topotecan. With these ploys, it is expected that advances will be made toward the optimization of [(131)I]MIBG therapy of neuroectodermal tumors.

Malignant pheochromocytomas and paragangliomas: a diagnostic challenge

INTRODUCTION

Malignant pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare disorders arising from the adrenal gland, from the glomera along parasympathetic nerves or from paraganglia along the sympathetic trunk. According to the WHO classification, malignancy of PCCs and PGLs is defined by the presence of metastases at non-chromaffin sites distant from that of the primary tumor and not by local invasion. The overall prognosis of metastasized PCCs/PGLs is poor. Surgery offers currently the only change of cure. Preferably, the discrimination between malignant and benign PCCs/PGLs should be made preoperatively.

METHODS

This review summarizes our current knowledge on how benign and malignant tumors can be distinguished.

CONCLUSION

Due to the rarity of malignant PCCs/PGLs and the obvious difficulties in distinguishing benign and malignant PCCs/PGLs, any patient with a PCC/PGL should be treated in a specialized center where a multidisciplinary setting with specialized teams consisting of radiologists, endocrinologist, oncologists, pathologists and surgeons is available. This would also facilitate future studies to address the existing diagnostic and/or therapeutic obstacles.

Survival of patients with metastatic malignant pheochromocytoma and efficacy of combined cyclophosphamide, vincristine, and dacarbazine chemotherapy

CONTEXT

About 10% of pheochromocytomas are malignant. Exact survival has not been reported, nor has an analysis of the efficacy of chemotherapy on survival time.

OBJECTIVE

The aim of this study was to analyze the survival curves and survival times of patients with malignant pheochromocytoma and to determine the efficacy of chemotherapy on prolongation of life.

DESIGN

An inception cohort and Kaplan-Meier survival analysis was conducted.

PATIENTS AND OUTCOME MEASURES

Thirty-two patients with metastasized malignant pheochromocytoma were analyzed for survival. Twenty-five patients had undergone excision of their primary tumors. Survival curves were compared among the 16 patients in this group treated with combined chemotherapy using cyclophosphamide, vincristine and dacarbazine (CVD) and the nine patients not treated with chemotherapy.

RESULTS

The survival curve of the 32 patients declined continuously and linearly to at least 20 yr after the diagnosis of pheochromocytoma. The 50% survival rate was estimated to be 14.7 yr. In the 25 patients whose primary tumor was excised, patients who already had metastases at the time of pheochromocytoma diagnosis had better survival than those whose metastases were found later. The survival rate after diagnosis of metastasis was worse in the CVD group than in controls. When the effects of CVD were examined after stratifying several factors, female gender and adrenal origin of tumor were found to be negative prognostic factors for CVD chemotherapy.

CONCLUSION

The present study revealed a long survival time. CVD chemotherapy was not shown to extend survival, especially for women and patients with adrenal gland-derived primary tumors.

Comparison of pheochromocytomas and abdominal and pelvic paragangliomas with head and neck paragangliomas

OBJECTIVE

To compare clinical, radiologic, and pathologic characteristics, as well as management and outcomes, in a series of pheochromocytomas, abdominal and pelvic paragangliomas, and pelvic paragangliomas with head and neck paragangliomas.

METHODS

In this retrospective study, we reviewed charts of all patients seen at our institution between January 1995 and December 2006. We searched pathology and medical record databases under the terms pheochromocytoma, paraganglioma, head and neck tumors, carotid body tumors, glomus jugulare, and neuroendocrine tumors. We compared clinical, radiologic, and pathologic characteristics, as well as management and outcomes, between patients with pheochromocytoma, abdominal and pelvic paraganglioma, and head and neck paraganglioma.

RESULTS

Eighty-six patients were included (46 with head and neck paraganglioma, 23 with pheochromocytoma, and 17 with abdominal or pelvic paraganglioma). Compared with patients with head and neck paraganglioma, patients with pheochromocytoma or abdominal and pelvic paraganglioma were younger (35.7 +/- 16 years vs 43 +/- 17 years, P = .042) and were more likely to have the classic triad associated with catecholamine hypersecretion of palpitation, excessive sweating, and headache (40% vs 0%, P<.001); hypertension (70% vs 37%, P = .005); and benign tumors (65% vs 43%, P = .03). Patients with head and neck paraganglioma and patients with pheochromocytoma/abdominal and pelvic paraganglioma were not different in female to male ratios (27:19 vs 29:11, respectively, P = .18), tumor size (5.8 +/- 2.7 cm vs 5.7 +/- 3 cm, respectively; P = .85), or remission rate (43% vs 60%, respectively, P = .13).

CONCLUSIONS

Head and neck paraganglioma are similar to pheochromocytoma and abdominal and pelvic paraganglioma in size and outcome, but occur at an older age, lack hyperadrenergic manifestations, and are more likely to have local pressure effects and result in persistent disease.

A kit method for the high level synthesis of [211At]MABG

meta-[(211)At]Astatobenzylguanidine ([(211)At]MABG), an analogue of meta-iodobenzylguanidine (MIBG) labeled with the alpha-emitter (211)At, targets the norepinephrine transporter. Because MABG has been shown to have excellent characteristics in preclinical studies, it has been considered to be a promising targeted radiotherapeutic for the treatment of tumors such as micrometastatic neuroblastoma that overexpress the norepinephrine transporter. To facilitate clinical evaluation of this agent, a convenient method for the high level synthesis of [(211)At]MABG that is adaptable for kit formulation has been developed. A tin precursor anchored to a solid-support was treated with a methanolic solution of (211)At in the presence of a mixture of H(2)O(2)/HOAc as the oxidant; [(211)At]MABG was isolated by simple solid-phase extraction. By using C-18 solid-phase extraction, the radiochemical yield from 25 batches was 63+/-13%; however, loss of radioactivity during evaporation of the methanolic solution was a problem. This difficulty was avoided by use of a cation exchange resin cartridge for isolation of [(211)At]MABG, which resulted in radiochemical yields of 63+/-9% in a shorter duration of synthesis. The radiochemical purity was more than 90% and no chemical impurity has been detected. The final doses were sterile and apyrogenic. These results demonstrate that [(211)At]MABG can be prepared via a kit method at radioactivity levels anticipated for initiation of clinical studies.