Surgical management of hereditary pheochromocytoma1 1No competing interests declared

The recognition and surgical management of heritable lesions of the pancreas

Our knowledge regarding the inherited factors that lead to the development of lesions within the pancreas is clearly incomplete. This article addresses clinical issues in patients at moderate-to-high risk for pancreatic malignancy, with special emphasis on the recognition and diagnosis of known genetic syndromes. Using the current available information, the authors attempt to equip the practicing surgeon with critical information to increase clinical suspicion for heritable syndromes and inform specific surgical management. Additionally, this article is meant to encourage the practicing surgeon to participate in the genetic testing/screening, cancer surveillance, and prevention activities of patients who have heritable cancer syndromes and associated pancreatic lesions that require surgery.

[Pheochromocytoma - still a challenge]

Pheochromocytomas are rare, mostly benign catecholamine-producing tumors arising from the chromaffin cells of the adrenal medulla or in the paraganglia. Clinical presentation is highly variable but typically with hypertension, severe headaches, palpitations and sweating. Biochemical testing by 24 h urinary fractioned metanephrines or catecholamines and plasma free metanephrines as the most sensitive screening approach, confirms the catecholamine excess. Computed tomography scan and magnetic resonance imaging of the adrenal glands and abdomen as well as functional imaging with (123)Iod-MIBG scintigraphy and (18)F-dopa positron emission tomography are used for tumor localization. Because approximately a quarter of tumors develop secondary to germ-line mutations, screening for genetic alterations is important. The therapy of choice is the endoscopic adrenal sparing surgery following preoperative alpha-blockade. Regular follow-up remains essential due to possible recurrence and malignancy.

Limitations of intraoperative adrenal remnant volume measurement in patients undergoing subtotal adrenalectomy

BACKGROUND

Recent studies have shown that a minimum of approximately one-third of one normal adrenal gland is required for sufficient adrenocortical stress capacity. Correlation between intraoperative measurement, determination of remnant size by computed tomography (CT), and adrenocortical stress capacity has not been examined so far.

METHODS

Twenty-two patients with familial pheochromocytoma (n=13), sporadic pheochromocytoma (n=3), and adrenocortical tumors (n=6) who underwent unilateral or bilateral subtotal adrenalectomy (STAE, 28 adrenal remnants) were prospectively studied. Patients were examined in a multi-slice CT to determine residual adrenal tissue and by ACTH test 4 days and 3 months postoperatively.

RESULTS

There was a slight significant correlation between intraoperative and CT calculated volumes (r=0.77; p<0.001). However, volumes assessed by CT were almost doubled compared with intraoperative determination (p<0.001). Although recovery of adrenal function could be observed, no significant changes of remnant volumes could be detected within 3 months. In patients with familial pheochromocytoma, there was a significant correlation between residual adrenal volume and stimulated cortisol levels (P<0.001). A distinct minimum of adrenal volume for intact adrenocortical stress capacity could not be exactly determined; however, in one patient with only 10% residual adrenal tissue intact stress capacity was found.

CONCLUSIONS

Residual adrenal tissue of approximately 10-15% offers intact stress capacity. However, an exact determination of the size of an adrenal remnant after STAE has limitations. CT gives larger volumes compared with intraoperative determination. For calculation of a volume-function correlation of residual adrenal tissue, in clinical practice, the determination of relative adrenal residual volume is acceptable.

Multiple endocrine neoplasia syndromes

The multiple endocrine neoplasia (MEN) syndromes are rare autosomal-dominant conditions that predispose affected individuals to benign and malignant tumors of the pituitary, thyroid, parathyroids, adrenals, endocrine pancreas, paraganglia, or nonendocrine organs. The classic MEN syndromes include MEN type 1 and MEN type 2. However, several other hereditary conditions should also be considered in the category of MEN: von Hippel-Lindau syndrome, the familial paraganglioma syndromes, Cowden syndrome, Carney complex, and hyperparathyroidism jaw-tumor syndrome. In addition, researchers are becoming aware of other familial endocrine neoplasia syndromes with an unknown genetic basis that might also fall into the category of MEN. This article reviews the clinical features, diagnosis, and surgical management of the various MEN syndromes and genetic risk assessment for patients presenting with one or more endocrine neoplasms.

Multiple endocrine neoplasia

MEN1 and MEN2 are autosomal dominant cancer syndromes with the potential for considerable morbidity and mortality. Better understanding of the molecular pathogenesis in MEN1 and MEN2 has fostered the development of specific DNA screening. Knowing the genetic status of patients is valuable for making decisions regarding surveillance and interventions, such as prophylactic thyroidectomy for medullary thyroid cancer. Identifying new RET pathways has provided molecular targets for therapies that currently are being tested in clinical trials for locally advanced, metastatic, and recurrent medullary thyroid cancer.

Laparoscopic partial adrenalectomy for bilateral pheochromocytomas

BACKGROUND

Patients with hereditary pheochromocytoma are at risk of the development of bilateral disease. Partial adrenalectomy can preserve adrenal function to avoid the morbidity associated with medical adrenal replacement. Here, we report a multimedia case study of synchronous bilateral partial adrenalectomy by the laparoscopic approach.

METHODS

A 13-year-old patient with von Hippel-Lindau disease was found to have high urinary metanephrines and normetanephrines. Computed tomography showed bilateral adrenal tumors (2.5 cm on the right side and 0.9 cm on the left). MIBG scan showed positive uptake in the right adrenal gland without extra-adrenal uptake. After adequate adrenergic blockade, the patient underwent laparoscopic partial adrenalectomy bilaterally.

RESULTS

The left side was approached first with the patient in the right decubitus position. Intraoperative ultrasound was performed to determine the line of tumor excision, which was carefully planned to preserve most of the normal-appearing gland. Both tumors were excised completely with good hemostasis. The main adrenal veins of both sides were precisely preserved. Operative time was 228 minutes. No clinically important hemodynamic fluctuations were noted. Pathologic examination confirmed bilateral entirely excised pheochromocytomas. The patient has not required exogenous corticosteroid replacement at follow-up.

CONCLUSION

Laparoscopic partial adrenalectomy for bilateral pheochromocytomas is safe and technically feasible. It should be considered the treatment of choice for hereditary pheochromocytoma.

Failure to recognize multiple endocrine neoplasia 2B: more common than we think?

BACKGROUND

Multiple endocrine neoplasia 2B (MEN2B) has a classic childhood phenotypic presentation characterized by mucosal neuromas and marfanoid habitus. However, the diagnosis of MEN2B is often delayed beyond childhood, at which time medullary thyroid carcinoma (MTC) may be regionally advanced or metastatic. We examined the extent of this delay and its impact on the treatment of MTC.

METHODS

Patients in the MEN database were retrospectively analyzed to determine the age at first presentation for a MEN2B-related complaint and the subsequent time to correct diagnosis. Operative and pathology reports were reviewed to determine the extent of thyroidectomy and cervical lymphadenectomy during the initial and subsequent neck operations.

RESULTS

We identified 22 patients with MEN2B, 20 were de novo cases and a M918T RET gene mutation was confirmed in 18 of the 22 patients. Median age at diagnosis of MTC was 13 years (range 6-25 years). The median delay in diagnosis was 26 months (range 0-18 years). Persistent local-regional MTC was present following the initial cervical operation in 12 of 22 patients (55%); including 4 of 13 with MEN2B diagnosed prior to initial surgery and 8 of 9 with MEN2B diagnosed after initial surgery.

CONCLUSIONS

Most patients displayed phenotypic characteristics of MEN2B long before the correct diagnosis was made. Half of the patients failed to undergo complete resection of MTC at their initial thyroid surgery. Early recognition of the MEN2B phenotype with a thoughtful approach to preoperative staging and surgery will maximize control of MTC and minimize the need for reoperation.

Pheochromocytoma: presentation, diagnosis and treatment

Pheochromocytomas are rare, mostly benign catecholamine-producing tumors of chromaffin cells of the adrenal medulla or of a paraganglion. Typical clinical manifestations are sustained or paroxysmal hypertension, severe headaches, palpitations and sweating resulting from hormone excess. However, their presentation is highly variable and can mimic many other diseases. If remaining unrecognized or untreated, they can be a life-threatening condition. Therefore, the most important message of this review is to think of them. The diagnosis of pheochromocytomas depends mainly upon the demonstration of catecholamine excess by 24-h urinary catecholamines and metanephrines or plasma metanephrines. They are localized by a computed tomography scan and magnetic resonance imaging of the adrenal glands and abdomen; complementary 123I-metaiodobenzylguanidine scintigraphy and 18F-dihydroxyphenylalanine-positron emission tomography are available. Because approximately one out of four pheochromocytomas turn out to be hereditary entities, screening for genetic alterations is important. Laparoscopic and adrenal sparing surgical intervention following preoperative alpha-blockade is the treatment of choice and usually curative. In malignant pheochromocytomas, radiotherapy and chemotherapy are palliative treatment options. This review provides an update on identification and management of pheochromocytomas, emphasizing current developments in diagnosis, including genetic testing, pathophysiology and treatment of pheochromocytomas.

Pheochromocytoma: advances in genetics, diagnosis, localization, and treatment

Pheochromocytomas are rare, catecholamine-secreting tumors arising most frequently in the chromaffin cells of the adrenal glands. Recent studies have suggested that genetic mutations are more frequent than previously appreciated in patients with these lesions. Advances continue to be made not only in the genetic evaluation of these patients but also in the biochemical confirmation and tumor localization. Surgery remains the definitive treatment, and advances in laparoscopic techniques as well as cortical-sparing procedures have reduced the morbidity associated with tumor resection.

Allogeneic transplantation and the risk for transmission of genetic disease: the heritable cancer disorders

With the development of new approaches to transplantation therapy, such as those building upon the potential found in stem cells, it is vital to pursue a clear understanding of transplantation risks. Allogeneic transplantation presents risk for the transmission of disease of various types, including genetic disease. Predisposition to develop cancer is a feature of numerous genetic disorders, and it may be transmissible by transplantation. Some genetic disorders predisposing to cancer are remarkably common, either worldwide or in specific populations, and they could pose significant risk. Hence, to reduce risk to recipients, there is reason to exclude from donation those potential donors (including embryos) harboring certain germ-line mutations. However, the frequent absence of readily identifiable features might confound the effort to exclude those who harbor mutation. Thus, it is also important to consider the magnitude of risk that they represent. For some disorders, life-threatening cancer is highly likely to develop in those individuals born with germ-line mutation, but whether recipients would face the same risk from transplanted mutation is not always evident. Given the diversity of pathways that lead to cancer, there may be diverse factors that impact the likelihood for cancer to develop in the recipient, with some factors decreasing and others increasing the risk. One factor of special concern is the possibility that manipulation of donor cells, prior to transplantation, might introduce additional genetic or epigenetic abnormality, thereby increasing the risk.

Pheochromocytoma: recommendations for clinical practice from the First International Symposium. October 2005

The First International Symposium on Pheochromocytoma, held in October 2005, included discussions about developments concerning these rare catecholamine-producing tumors. Recommendations were made during the symposium for biochemical diagnosis, localization, genetics, and treatment. Measurement of plasma or urinary fractionated metanephrines, the most accurate screening approach, was recommended as the first-line test for diagnosis; reference intervals should favor sensitivity over specificity. Localization studies should only follow reasonable clinical evidence of a tumor. Preoperative pharmacologic blockade of circulatory responses to catecholamines is mandatory. Because approximately a quarter of tumors develop secondary to germ-line mutations in any one of five genes, mutation testing should be considered; however, it is not currently cost effective to test every gene in every patient. Consideration of tumor location, presence of multiple tumors, presence of metastases, and type of catecholamine produced is useful in deciding which genes to test. Inadequate methods to distinguish malignant from benign tumors and a lack of effective treatments for malignancy are important problems requiring further resolution.

Treatment of bilateral pheochromocytoma and adrenal medullary hyperplasia

The risk for bilateral tumors and long-term outcome after conservative cortical-sparing adrenal surgery was studied in a consecutive single-center series. One hundred fifty-four patients were operated on (1950-2004) for pheochromocytoma (PC=137), or abdominal paraganglioma (PG=17). Twenty had MEN 2 (16 MEN 2A; 4 MEN 2B), 15 von Recklinghausen's disease (VRD), and 1 von Hippel-Lindau (VHL) disease. Twelve patients had, or developed, bilateral adrenal medullary tumors; four with MEN 2A, four with MEN 2B, three with VRD, and one with probably hereditary PC associated with brain tumors/meningioma. Two patients with MEN 2B and one with MEN 2A with had bilateral adrenalectomy (adx). Three VRD patients, two MEN 2B and one MEN 2A patients had cortical-sparing surgery. Two patients were operated on unilaterally, but developed small contralateral tumors; one of these (MEN 2A) had a second asymptomatic PC diagnosed at an older age, so surgery was withheld; the other patient (hereditary PC syndrome) had a small contralateral PC diagnosed at autopsy 9 years later. Only three of nine patients with bilateral operations needed corticosteroid replacement after surgery. Four of six patients died of associated tumors (MTC and meningioma). The mean follow-up was 13 (1-25) years. Twelve MEN 2A patients with unilateral adx have been followed up for 20 (4-36) years without developing a second PC. Cortical-sparing adrenal surgery can safely be performed in the majority of patients with bilateral PC. On the basis of our long-term experience of MEN 2A we perform contralateral adrenal resection only if a second PC is confirmed. Five patients underwent adrenal exploration because of clinical and biochemical findings compatible with PC. Four had asymmetrical positive MIBG scans. They all underwent unilateral adx and diffuse medullary hyperplasia was confirmed (medullary weight estimated morphometrically to 1.0-3.4 g vs. normal weight 0.3-0.5 g in matched controls). These patients have been followed for 19 (5-27) years with normal clinical and biochemical findings. In this rare condition removal of the largest adrenal seems adequate.

Abdominal visceral lesions in von Hippel-Lindau disease: incidence and clinical behavior of pancreatic and adrenal lesions at a single center

INTRODUCTION

Von Hippel-Lindau disease (VHL) is a dominantly inherited multi-system syndrome. Although pheochromocytoma is the hallmark endocrine neoplasm, pancreatic lesions occur frequently, and their management can be complex. This report describes 26 patients from a single institution with pancreatic or adrenal lesions (or both) in the background of VHL.

METHODS

We reviewed records for all patients treated for adrenal (type 2 VHL) or pancreatic manifestations of VHL at our institution from 1990 to 2004.

RESULTS

Forty patients with VHL were identified from 24 pedigrees; 26 (65%) had adrenal or pancreatic involvement (or both). Seven patients had isolated pheochromocytomas, 16 had isolated pancreatic lesions, and 3 had both. Of the 10 patients with pheochromocytomas, 4 had bilateral adrenal involvement. All but three pheochromocytomas were diagnosed in patients aged 40 years or younger. Of the 19 patients with pancreatic lesions, 8 had cystic lesions, 8 had neuroendocrine tumors, and 3 had both. Of 11 patients with neuroendocrine tumors, 4 had metastases (3 hepatic, 1 nodal). No patient with cystic pancreatic lesions developed carcinoma.

CONCLUSIONS

VHL should be familiar to the endocrine surgeon because of the high incidence (65% in our series) of visceral endocrine lesions (pancreas 40%, adrenal gland 18%, both 7%). As seen in other hereditary endocrinopathy syndromes, pheochromocytomas are frequently bilateral; therefore,close follow-up of the contralateral gland in young patients with a unilateral lesion is critical. Cystic lesions of the pancreas may be closely monitored, whereas neuroendocrine tumors should be removed because of the risk of metastasis. Pancreatic pathology is not uncommon in VHL patients with pheochromocytoma and should be sought during the preoperative assessment.

Pheochromocytoma and paraganglioma in children: a review of medical and surgical management at a tertiary care center

OBJECTIVE

The aim of this study was to review our institutional experience managing pheochromocytomas and paragangliomas in children.

METHODS

A retrospective chart review of the Mayo Clinic database from 1975 to 2005 identified 30 patients < 18 years of age with histologically confirmed pheochromocytoma or paraganglioma.

RESULTS

There were 12 patients with pheochromocytomas and 18 with paragangliomas. The most common presenting symptoms were hypertension (64%), palpitation (53%), headache (47%), and mass-related effects (30%). Nine patients (30%) had a genetic mutation or documented family history of pheochromocytoma or paraganglioma. Fourteen patients (47%) had malignant disease, whereas 16 (53%) had benign disease. Logistic analysis showed that statistically significant risk factors for malignancy were (1) paraganglioma, (2) apparently sporadic, as opposed to familial, pheochromocytoma or paraganglioma, and (3) tumor size of > 6 cm. Surgical resection was performed for 28 patients (93%), with perioperative mortality and major morbidity rates of 0% and 10%, respectively. Resection achieved symptomatic relief for 25 patients (83%). All patients with benign disease appeared cured after resection. For patients with malignant disease, the 5- and 10-year disease-specific survival rates were 78% and 31%, respectively, and the mean survival time was 157 +/- 32 months.

CONCLUSIONS

The incidence of malignant pheochromocytoma/paraganglioma was high in children (47%), particularly those with apparently sporadic disease, paraganglioma, and tumor diameters of > 6 cm. Patients with a known genetic mutation or familial pheochromocytoma/paraganglioma were more likely to achieve resection with negative microscopic margins and had improved disease-specific mortality rates. Surgical resection remains the treatment of choice for pheochromocytoma and paraganglioma.

NEW ERA: PROPHYLACTIC SURGERY FOR PATIENTS WITH MULTIPLE ENDOCRINE NEOPLASIA-2A

BACKGROUND

The surgical management of patients with multiple endocrine neoplasia-2A (MEN-2A) continues to evolve with specific genotype-phenotype correlations allowing for a more tailored approach. In this study, we report the surgical management of one of the largest MEN-2A families with a rearranged during transfection (RET) codon 804 mutation.

METHOD

This is a cohort study comprising all at-risk kindred within a single known MEN-2A family. Prophylactic total thyroidectomy with lymph node dissection was recommended to all mutation carriers aged 5 years and older.

RESULTS

There were a total of 48 at-risk individuals in the MEN-2A kindred, with 22 patients undergoing thyroidectomy after appropriate preoperative evaluation. A total of 9 patients had medullary thyroid cancer including 5 with a normal preoperative calcitonin level. A total of 11 patients had C-cell hyperplasia and 7 showed histological evidence of parathyroid disease. Only the index case had a phaeochromocytoma.

CONCLUSIONS

Genetic testing for germline mutations in the RET proto-oncogene has allowed precise identification of affected RET carriers and provided the opportunity for prophylactic or 'preclinical' surgery to treat and in fact to prevent medullary thyroid cancer. This concept of prophylactic surgery based on a genetic test is likely to be applied more widely as the tools of molecular biology advance.

Surgical intervention in children with multiple endocrine neoplasia type 2

PURPOSE OF REVIEW

We provide a summary of the literature published in the past year addressing the surgical approach to multiple endocrine neoplasia type 2 in the pediatric population.

RECENT FINDINGS

The review focuses first on medullary thyroid carcinoma and performing prophylactic thyroidectomy for the prevention or cure of this disease. The timing and extent of surgery as well as additional surgical intervention for persistent or recurrent disease is discussed. Then the surgical management of hereditary pheochromocytoma is reviewed.

SUMMARY

Surgery is often the only treatment that can prevent or cure the endocrinopathies associated with multiple endocrine neoplasia type 2. Determining the proper timing and extent of surgical intervention in children affected with multiple endocrine neoplasia type 2 will lead to better outcomes and survival.

Laparoscopic Resection of a Paraganglioma of the Organ of Zuckerkandl in a Patient with a Carotid Body Tumor

Paragangliomas of the organ of Zuckerkandl are rare tumors with only several case reports noted in the literature. Synchronous paraganglioma occur sporadically, and on occasion, in association with several genetic syndromes. Paraganglioma of the organ of Zuckerkandl with synchronous carotid body paraganglioma is described herein. Traditionally, surgical resection of abdominal paraganglioma involved an exploratory laparotomy. In this manuscript, we describe one of the first reported laparoscopic resections of this tumor and review the literature on multiple paragangliomas and their associated genetic syndromes.

Phaeochromocytoma

Phaeochromocytomas are rare neuroendocrine tumours with a highly variable clinical presentation but most commonly presenting with episodes of headaches, sweating, palpitations, and hypertension. The serious and potentially lethal cardiovascular complications of these tumours are due to the potent effects of secreted catecholamines. Biochemical testing for phaeochromocytoma is indicated not only in symptomatic patients, but also in patients with adrenal incidentalomas or identified genetic predispositions (eg, multiple endocrine neoplasia type 2, von Hippel-Lindau syndrome, neurofibromatosis type 1, and mutations of the succinate dehydrogenase genes). Imaging techniques such as CT or MRI and functional ligands such as (123)I-MIBG are used to localise biochemically proven tumours. After the use of appropriate preoperative treatment to block the effects of secreted catecholamines, laparoscopic tumour removal is the preferred procedure. If removal of phaeochromocytoma is timely, prognosis is excellent. However, prognosis is poor in patients with metastases, which especially occur in patients with large, extra-adrenal tumours.

RET proto-oncogene: a review and update of genotype-phenotype correlations in hereditary medullary thyroid cancer and associated endocrine tumors

Hereditary medullary thyroid carcinoma (MTC) is caused by autosomal dominant gain-of-function mutations in the RET proto-oncogene. Associations between specific RET mutations (genotype) and the aggressiveness of MTC and presence or absence of other endocrine neoplasms (phenotype) are well documented. Mutations in six exons (10, 11, 13, 14, 15, and 16) located in either cysteine-rich or tyrosine kinase domains cause one of three distinctive clinical subtypes: familial MTC, multiple endocrine neoplasia (MEN) type 2A (including variants with Hirschsprung's disease and cutaneous lichen amyloidosis), and MEN 2B. Hallmarks of MEN 2A include MTC, pheochromocytoma, and hyperparathyroidism. MEN 2B is associated with an earlier onset of MTC and pheochromocytoma, the absence of hyperparathyroidism, and the presence of striking physical stigmata (e.g., coarse facies, ganglioneuromatosis, and marfanoid habitus). Familial MTC is not associated with other endocrine neoplasms; however, the accurate distinction between familial MTC and MEN 2A may be difficult in kindreds with small size, incomplete histories, or a predominance of young individuals who may not have yet fully manifested the syndrome. Genetic testing detects greater than 95% of mutation carriers and is considered the standard of care for all first-degree relatives of patients with newly diagnosed MTC. Recommendations on the timing of prophylactic thyroidectomy and the extent of surgery are based upon a model that utilizes genotype- phenotype correlations to stratify mutations into three risk levels.

Wiederholungseingriffe an den Nebennieren

Repeat adrenalectomy may be required due to ipsilateral recurrence of benign or malignant adrenal tumors after previous total or subtotal adrenalectomy. Even for multivisceral resection in patients with adrenocortical carcinoma, complete resection of local recurrent tumor offers results similar to those of primary resection (5-year survival 40-60%). In contrast, since no benefit on long-term survival has been shown so far by tumor debulking, palliative tumor resection should only be performed individually for control of severe endocrine symptoms. The effect of endoscopic adrenalectomy in patients with large tumors (>5 cm) or suspected malignancy has still not been well examined. Further studies are required. In any case, during open or endoscopic approach, tumor spillage must be avoided to prevent local tumor cell implantation. Following subtotal adrenalectomy, the risk of ipsilateral recurrence correlates with disease, follow-up, localization, size of the adrenal remnant, and, in case of familial pheochromocytoma, probably with genotype.

Recent developments in the therapy of phaeochromocytoma

The basic principles of treatment for phaeochromocytomas and paragangliomas are to block the effects of high catecholamines and make the patient safe for surgical removal of the tumour. The traditional preoperative medical preparation uses the non-selective alpha-adrenoceptor blocker phenoxybenzamine and a beta-adrenoceptor blocker, propranolol. Other agents have been used effectively, including selective alpha-adrenoceptor blockers, doxazosin and prazosin, and calcium channel antagonists. There have been no trial comparing regimens and there is some controversy as to the best regimen. Major advances have been made in laparoscopic and laparoscopic-assisted surgery. Cortical-sparing adrenalectomy has been used in some centres for familial phaeochromocytomas. High-dose [(131)I]-metaiodobenzylguanidine therapy and combined [(131)I]-metaiodobenzylguanidine and chemotherapy are promising new developments for the malignant disease. All patients should be followed indefinitely because the recurrence or malignancy rate is >or= 10% over a prolonged follow up.

Hereditary cancer predisposition syndromes

Cancer genetics is increasingly becoming integrated into the practice of modern medical oncology. The ability to distinguish a growing proportion of the 5% to 10% of all cancers that develop in individuals who have inherited a genetic mutation conferring heightened susceptibility to specific cancers may permit targeted efforts in cancer surveillance and prevention. While these individuals comprise a small proportion of the overall burden of cancer, strategies successful in reducing their remarkable cancer risks may be generalizable to the broader population. In this review, we highlight the most common hereditary cancer syndromes, most attributable to genes inherited in an autosomal dominant manner with incomplete penetrance, and a number of rare syndromes in which particular progress has been made. The prevalence, penetrance, tumor spectrum, and underlying genetic defects are discussed and summarized in a large table in which a more comprehensive enumeration of syndromes is provided.