Prognostic Scoring System to Risk Stratify Parathyroid Carcinoma

Clinical course of atypical parathyroid neoplasm with soft tissue extension

BACKGROUND AND OBJECTIVES

The American Joint Committee on Cancer (AJCC) TNM staging system defines atypical parathyroid neoplasia (APN) as tumor in situ (Tis) and reserves the definition of parathyroid carcinoma (PC) to parathyroid tumor with invasion into surrounding structures. Because the parathyroid gland has no true capsule, "extension" with APN versus microscopic "invasion" of surrounding soft tissue can be difficult and confusing for clinicians. We aimed to determine the clinical course of atypical parathyroid neoplasm with and without soft tissue extension and parathyroid carcinoma with only soft tissue invasion (pT1) and to report the outcomes.

METHODS

Following an IRB-approved protocol, we identified all patients treated for parathyroid neoplasm or cancer at our single tertiary care cancer center from 1990 to 2021. We excluded all patients with evidence of clinical or pathologic gross invasion into surrounding structures (pT2 or higher), lymph node involvement, or metastatic disease. By definition, this excluded all cases where the distinction was clinically evident to the surgeon at the time of the operation based on finding a hard, firm, sticky, or discolored parathyroid gland. Only patients with pathologic T1 (pT1) parathyroid carcinoma or APN were included. All pathologic examinations were independently re-reviewed by a single designated expert senior endocrine pathologist. The definition of APN strictly followed the WHO definition of a clinically worrisome lesion having features including fibrous bands or increased mitotic rate, necrosis, or trabecular growth that did not meet robust criteria for frank invasion. Pathologic T1 disease was defined as invasion limited to soft tissue. Analyses were performed using R version 4.0.2 and Jamovi.

RESULTS

Of all PC patients at our institution, only 71 met the strict inclusion criteria of APN or pT1. Forty-four patients had pT1 disease and 27 had APN: 12 of the APN had soft tissue extension, and 15 had no soft tissue extension. The groups were similar with regard to age at diagnosis (p = 0.328). The average follow-up duration was 84 months from initial surgical intervention. Of the 12 with APN, one patient (1/12; 8%) with soft tissue extension recurred, developed distant metastases, and subsequently died during follow up. Of the 44 patients with pT1 PC, six developed distant metastases and 13 (13/44; 30%) died during the follow-up period. One patient with APN and soft tissue extension recurred and died and no patient with APN and no soft tissue extension died.

CONCLUSIONS

Patients with APN and extension into soft tissue have a clinical course similar to that of APN without soft tissue extension. APN with soft tissue extension is a different disease from pT1 disease with invasion of soft tissue. The pTis classification appears justified for APN with and without soft tissue extension.

Management and surgical treatment of parathyroid carcinoma: a 6-year experience of a single centre of endocrine surgery unit

Background

Parathyroid carcinoma (PC) affects 0.1-0.3% of the general population and represents the rarest malignant neoplasms among endocrinological diseases, comprising less than 1%. The best therapeutic treatment and management methods are still debated in the literature. The aim of this study is to evaluate the management and surgical treatment of parathyroid carcinoma after 6 years of enrolment with the Endocrine Surgery Unit of the University Hospital of Bari.

Materials and methods

A retrospective observational study was carried out using a prospectively maintained database of patients affected by primary hyperparathyroidism between January 2017 and September 2022. Consecutive patients over 18 years old with a final histopathological finding of PC were included in the study. Patients with secondary or tertiary hyperparathyroidism, parathyroid hyperplasia, and parathyroid adenoma were excluded. All patients underwent follow-up every 6 months for the first 2 years, and annually thereafter.

Results

In this study, 9 out of 40 patients affected by hyperparathyroidism were included; 6 (66.6%) were female and 3 (33.3%) were male patients, with a median age of 59 years (IQR 46-62). None had a family history of PC. No mortality was recorded while the incidence of recurrence was 22.2%, with a disease-free survival of 8 and 10 months. Parathyroidectomy was performed in five patients, while four patients underwent parathyroidectomy with concurrent thyroidectomy for thyroid goitre. No intraoperative complications were recorded. Open parathyroidectomy was performed with a mini-cervicotomy in seven patients, while two patients underwent robotic surgery. All patients were discharged on the second postoperative day.

Conclusion

PC represents a great challenge in terms of preoperative diagnosis, management and treatment. A surgical approach represents the first best option for PC in referral endocrine surgery units. The early identification of risky patients should be the dominant goal to plan an appropriate therapy and to perform adequate en bloc surgery.

Comparison of prognosis after partial and total surgical resection for parathyroid carcinoma: an inverse probability of treatment weighting analysis of the SEER database

Background

Complete resection of the tumor and the ipsilateral thyroid lobe at the primary surgery is the "gold standard" for the treatment of parathyroid carcinoma (PC). However, differences in the overall survival (OS) of patients with PC who underwent partial and total surgical resection remain to be determined.

Methods

Data on patients with PC who underwent partial and total surgical resection were extracted from the Surveillance, Epidemiology and End Results (SEER) database (2000-2018). The X-tile software (https://medicine.yale.edu/lab/rimm/research/software/) was used to define the optimal cut-off values for continuous variables. The inverse probability of treatment weighting (IPTW) method was used to reduce the selection bias. IPTW-adjusted Kaplan-Meier curves and Cox proportional hazards models were used to compare the OS of patients with PC in the partial and total surgical resection groups.

Results

A total of 334 patients with PC were included in this study (183 and 151 in the partial and total surgical resection groups, respectively). The optimal cut-off values for age at diagnosis were 53 and 73 years, respectively, while that for tumor size was 34 mm. In both the Kaplan-Meier analysis and univariable Cox proportional hazards regression analysis before IPTW, the difference in OS between the partial and total surgical resection groups was not statistically significant (p>0.05). These findings were confirmed in the IPTW-adjusted Kaplan-Meier analysis and multivariate Cox proportional hazards regression analysis (p>0.05). Subgroup analysis revealed that total surgical resection was beneficial for OS only in the subgroup with unknown tumor size.

Conclusion

There was no significant difference in the prognosis of patients who underwent partial and total surgical resection. This finding may provide a useful reference for the treatment of PC.

Parathyroid Retrospective Analysis of Neoplasms Incidence (pTRANI Study): An Italian Multicenter Study on Parathyroid Carcinoma and Atypical Parathyroid Tumour

BACKGROUND

Parathyroid cancer (PC) is a rare sporadic or hereditary malignancy whose histologic features were redefined with the 2022 WHO classification. A total of 24 Italian institutions designed this multicenter study to specify PC incidence, describe its clinical, functional, and imaging characteristics and improve its differentiation from the atypical parathyroid tumour (APT).

METHODS

All relevant information was collected about PC and APT patients treated between 2009 and 2021.

RESULTS

Among 8361 parathyroidectomies, 351 patients (mean age 59.0 ± 14.5; F = 210, 59.8%) were divided into the APT (n = 226, 2.8%) and PC group (n = 125, 1.5%). PC showed significantly higher rates (p < 0.05) of bone involvement, abdominal, and neurological symptoms than APT (48.8% vs. 35.0%, 17.6% vs. 7.1%, 13.6% vs. 5.3%, respectively). Ultrasound (US) diameter >3 cm (30.9% vs. 19.3%, p = 0.049) was significantly more common in the PC. A significantly higher frequency of local recurrences was observed in the PC (8.0% vs. 2.7%, p = 0.022). Mortality due to consequences of cancer or uncontrolled hyperparathyroidism was 3.3%.

CONCLUSIONS

Symptomatic hyperparathyroidism, high PTH and albumin-corrected serum calcium values, and a US diameter >3 cm may be considered features differentiating PC from APT. 2022 WHO criteria did not impact the diagnosis.

Parathyroid carcinoma: lessons from a rare malignancy of head and neck-a case series

Parathyroid carcinoma (PC) is a very rare head-neck malignancy. Because the symptoms of parathyroid carcinoma are similar to those of benign causes of hyperparathyroidism, it may be not easy to detect it before surgery. The management of PC after initial surgery will be perplexing because of the adequacy of surgery. We wish to describe the difficulties encountered throughout treatment using a literature review. We conducted a retrospective analysis of individuals with parathyroid carcinoma who had treatment at our department between 2017 and 2022. We gathered data on the clinical profile, investigations, management of hypercalcemia, surgical techniques, histopathological features, adjuvant therapy, and outcomes. We treated three patients with parathyroid carcinoma: Two patients with inferior parathyroid carcinoma and one with superior parathyroid carcinoma. Generalized weakness and bony pain are the predominant symptoms. In all cases, the tumor was located using 99Tc MIBI / SPECT scintigraphy and Ultrasonography. Hemithyroidectomy and tumor excision were done as the surgery of choice. All are disease-free at the 12th-month follow-up. We suggested that parathyroid hormone testing be performed in all bony fibrous lesions to rule out hyperparathyroidism. PC is a likely diagnosis when there is noticeable throat swelling, elevated PTH levels greater than 400 IU/L, and serum calcium levels greater than 15 mg/dL.

A Nomogram for Relapse/Death and Contemplating Adjuvant Therapy for Parathyroid Carcinoma

Parathyroid carcinoma (PC) is a rare endocrine malignancy with an increased incidence in the last decade. There is no reliable prognostic staging system for PC. Several hosts, tumors, and tumor microenvironment factors have been negatively correlated with survival in the last decade. Surgical resection with negative margins is still the standard of treatment in PC. Chemo and radiotherapy have no proven beneficial effect. A new promising approach with molecular profiling could lead to adjuvant therapies.

Advances and Updates in Parathyroid Pathology

Hyperparathyroidism is a common endocrine disorder characterized by elevated levels of parathyroid hormone and hypercalcemia and is divided into 3 types: primary, secondary, and tertiary. Distinction between these types is accomplished by correlation of clinical, radiologic, and laboratory findings with pathologic features. Primary hyperparathyroidism occurs sporadically in 85% of cases with the remaining cases associated with multiple familial syndromes. The pathologic manifestations of primary hyperparathyroidism include parathyroid adenoma, parathyroid hyperplasia, and parathyroid carcinoma. Recent advances in the understanding of the pathogenesis of parathyroid disease has helped to refine the diagnosis and classification of parathyroid lesions. The identification of multiple clonal proliferations in traditional multiglandular parathyroid hyperplasia has led to the adoption by the World Health Organization (WHO) of the alternate term of primary hyperparathyroidism-related multiglandular parathyroid disease. Additional nomenclature changes include the adoption of the term atypical parathyroid tumor in lieu of atypical parathyroid adenoma to reflect the uncertain malignant potential of these neoplasms. Clinical and morphologic features characteristic of familial disease have been described that can help the practicing pathologist identify underlying familial disease and provide appropriate management. Use of ancillary immunohistochemistry and molecular studies can be helpful in classifying parathyroid neoplasms. Parafibromin has proven useful as a diagnostic and prognostic marker in atypical parathyroid tumors and parathyroid carcinomas. This review provides an update on the diagnosis and classification of parathyroid lesions considering the recent advances in the understanding of the molecular and clinical features of parathyroid disease and highlights the use of ancillary studies (immunohistochemical, and molecular) to refine the diagnosis of parathyroid lesions.

Advances in Endocrine Surgery

Recent changes in the landscape of endocrine surgery include a shift from total thyroidectomy for almost all patients with papillary thyroid cancer to the incorporation of thyroid lobectomy for well-selected patients with low-risk disease; minimally invasive parathyroidectomy with, and potentially without, intraoperative parathyroid hormone monitoring for patients with well-localized primary hyperparathyroidism; improvement in the management of parathyroid cancer with the incorporation of immune checkpoint blockade and/or targeted therapies; and the incorporation of minimally invasive techniques in the management of patients with benign tumors and selected secondary malignancies of the adrenal gland.

Margin Free Resection Achieves Excellent Long Term Outcomes in Parathyroid Cancer

Long-term outcomes of parathyroid cancer remain poorly documented and unsatisfactory. This cohort includes 25 consecutive parathyroid cancer patients with median follow-up of 10.7 years (range 4.1−26.5 years). Pre-operative work-up in the center identified a suspicion of parathyroid cancer in 17 patients. En bloc resection, including the recurrent laryngeal nerve in 4/17 (23.5%), achieved cancer-free resection margins (R0) in 82.4% and lasting loco-regional disease control in 94.1%. Including patients referred after initial surgery elsewhere, R0 resection was achieved in merely 17/25 (68.0%) of patients. Cancer-positive margins (R1) in 8 patients led to local recurrence in 50%. On multivariate analysis, only margin status prevailed as independent predictor of recurrence free survival (χ2 19.5, p < 0.001). Local excision alone carried a 3.5-fold higher risk of positive margins than en bloc resection (CI95: 1.1−11.3; p = 0.03), and a 6.4-fold higher risk of locoregional recurrence (CI95: 0.8−52.1; p = 0.08). R1-status was associated with an 18.0-fold higher risk of recurrence and redo surgery (CI95: 1.1−299.0; p = 0.04), and a 22.0-fold higher probability of radiation (CI95: 1.4−355.5; p = 0.03). In patients at risk, adjuvant radiation reduced the actuarial risk of locoregional recurrence (p = 0.05). When pre-operative scrutiny resulted in upfront oncological surgery achieving cancer free margins, it afforded 100% recurrence free survival at 5- and 10-year follow-up, whilst failure to achieve clear margins caused significant burden by outpatient admissions (176 vs. 4 days; χ2 980, p < 0.001) and exposure to causes for concern (1369 vs. 0 days; χ2 11.3, p = 0.003). Although limited by cohort size, our study emphasizes the paradigm of getting it right the first time as key to improve survivorship in a cancer with excellent long-term prognosis.

Management of Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is the unregulated overproduction of parathyroid hormone (PTH) resulting in abnormal calcium homeostasis. The disease profile has evolved over the last century from symptomatic hyperparathyroidism to asymptomatic hyperparathyroidism. Primary hyperparathyroidism is a biochemical diagnosis. Parathyroidectomy is the only established cure for this disease. Every effort is made to localize the offending gland preoperaively with various imaging modalities. These localization studies along with intraoperative parathormone monitoring will direct the surgeon to either a focused parathyroidectomy or a four gland exploration. All symptomatic patients and asymptomatic patients who meet the criteria for surgery should undergo parathyroidectomy if no medical contraindications exist. Pharmacologic approaches are reserved for those patients unfit or unwilling to undergo surgery.

Prognostic Analysis for Patients With Parathyroid Carcinoma: A Population-Based Study

Background

Parathyroid carcinoma (PC) is a rare but often lethal malignancy for which staging system, prognostic indicators, and treatment guidelines are still not established. We aimed to explore the prognostic parameters and construct a nomogram for cancer-specific survival (CSS) of PC.

Methods

A retrospective analysis of 604 PC patients in the SEER database from 2001 through 2018 was performed. All the cases were randomly assigned to the training cohort (n = 424) or the validation cohort (n = 180) at a ratio of 7:3. The Kaplan–Meier method and Cox regression model were applied to estimate the CSS and risk factors, and a nomogram was constructed. The predictive accuracy and discriminative ability of the nomogram in CSS were assessed by concordance index (C-index), the area under the curve (AUC) of receiver operating characteristics (ROC), and the calibration curve.

Results

Age at diagnosis > 70 years [hazard ratio (HR): 3.55, 95% CI: 1.07–11.78, p = 0.039] and tumor size > 35 mm (HR 4.22, 95% CI: 1.67–10.68, p = 0.002) were associated with worse CSS. Compared with distant metastasis, localized (HR 0.17, 95% CI: 0.06–0.47, p = 0.001) and regional lesions (HR 0.22, 95% CI: 0.07–0.66, p = 0.007) showed an improved CSS rate. Parathyroidectomy was the recommended treatment (p = 0.02). The C-index of the nomogram was 0.826, and the AUC for 5-, 10-, and 15-year CSS was 83.7%, 79.7%, and 80.7%, respectively. The calibration curve presented good agreement between prediction by nomogram and actual observation.

Conclusion

Age at diagnosis > 70 years, tumor size > 35 mm, and distant metastasis were independent risk factors for PC-specific mortality. Parathyroidectomy was currently the most recommended treatment for PC. This nomogram provided individualized assessment and reliable prognostic prediction for patients with PC.

A Nomogram Predicting the Overall Survival and Cancer-Specific Survival in Patients with Parathyroid Cancer: A Retrospective Study

PURPOSE

This study aimed to explore a visual model for predicting the prognosis of patients with parathyroid carcinoma (PC) and analyze related biochemistries in different groups of stage.

METHODS

The training dataset of 342 patients with PC was obtained from the Surveillance, Epidemiology, and End Results (SEER) database, and the validation dataset included 59 patients from The First Affiliated Hospital of Zhengzhou University. Univariate and multivariate Cox regression analyses were performed to evaluate significant independent prognostic factors. Based on those factors, nomograms and Web-based probability calculators were constructed to evaluate the overall survival (OS) and the cancer-specific survival (CSS) at 3, 5, and 8 years. The concordance index (C-index), receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) were used to evaluate the nomogram in the training set and validation set. Moreover, biochemistries from the validation set were retrospectively analyzed in different groups of stage by Kruskal-Wallis test.

RESULTS

Age, marital status, tumor size, stage, lymph node status, and radiation were identified as prognostic factors of OS. In contrast, only tumor size and stage were predictive for CSS. The nomogram was developed based on these independent factors. The C-index, ROC curve, calibration curve, and DCA of the nomogram in both training and validation sets showed that the nomogram had good predictive value, stability, and clinical benefit in predicting 3-, 5-, and 8-year OS and CSS in PC patients. Among the 59 PC patients from our hospital, lower albumin (ALB) levels and higher postoperative parathyroid hormone (PTH) levels were found in patients with distant metastasis (Distant vs. Regional ALB levels: p = 0.037; Distant vs. Local ALB levels: p = 0.046; Distant vs. Regional postoperative PTH levels: p = 0.002; Distant vs. Local postoperative PTH: p = 0.002).

CONCLUSION

The established nomogram application can provide accurate prognostics for patients with PC in the Chinese population, but it must be validated on prospectively collected real-world data.

Extended En Bloc Reoperation for Recurrent or Persistent Parathyroid Carcinoma: Analysis of 31 Cases in a Single Institute Experience

BACKGROUND

Parathyroid carcinoma (PC) is a rare malignancy that is difficult to eradicate completely after recurrence. We assessed the efficiency of extended en bloc resection (EEBR) in the management of recurrent or persistent PC.

METHODS

In this observational cohort study, 31 patients who underwent reoperations for recurrent or persistent PC were enrolled after 2-9 surgeries by other medical teams. EEBRs, which provided the oncologic resection by removing all possible tumor-bearing scar tissues, were adopted in 25 patients. The other 6 with gross infiltration into the upper aerodigestive tract (UAT) underwent less radical procedures for unwillingness to sacrifice laryngeal function.

RESULTS

The 5-year overall survival (OS) rate after EEBR was 59.6% compared with 16.7% after less radical procedures, with an improved median expected survival time of 90.0 months compared with 13.0 months after local excision. EEBR exhibited a favorable local control of relapses in 84.0% of patients after a median follow-up period of 27.0 months, 40.0% even achieved disease-free survival, although 56.0% had subsequent distant metastases (DMs) and suffered a worse 5-year OS of 36.7% in contrast with 100.0% in the absence of DM (p = 0.011). UAT invasion, rather than age, number of previous operations, or preoperative PTH levels, was the unique independent factor associated with both DM (HR = 5.466, p = 0.006) and mortality (HR = 7.606, p = 0.011).

CONCLUSION

EEBRs provide better outcomes than other conventional surgical approaches and might offer a second chance of cure for patients with recurrent or persistent PC in the absence of DM.

Management and Outcome of Parathyroid Carcinoma-Induced Primary Hyperparathyroidism: A Single-Centre Experience

BACKGROUND

Parathyroid carcinoma (PC) is the rarest endocrine cancer and an infrequent cause of primary hyperparathyroidism (PHPT), responsible for less than 1% of cases. Due to its rarity, treatment is challenging.

METHODS

A retrospective cohort study on 462 patients referred for parathyroidectomy to Thyroid and Parathyroid Unit at Santi Paolo e Carlo Hospital, Milan, Italy, from 2011 to 2021. We identified and individually described the patients affected with PC. Then, we split all patients treated for PHPT into four groups based on the cause: PC, adenoma, atypical adenoma, and hyperplasia. Patients' demographics, preoperative evaluation results, intraoperative findings, and outcomes for the PC group were compared with groups of PHPT due to benign causes.

RESULTS

Eight cases of PC were identified, five males and three females. Seven cases presented with symptoms of hypercalcemia and one with a neck mass. Five underwent en bloc resections and three local excisions. Histopathological features showed capsular invasion in four patients, capsular and soft tissue invasion in three patients, and vascular invasion in one case. No patients had distant metastasis. One patient was classed as high risk based on the Schulte classification system. All patients treated for PC were alive and disease-free at a mean follow-up of 38.4 months. When compared with other PHPT patients, PC patients were more frequently male and had higher preoperative blood calcium and PTH and lower phosphate levels, larger and heavier parathyroids excised, lower postoperative calcium, and a higher rate of postoperative hypoparathyroidism.

CONCLUSION

Our study highlights some aspects valuable to suspect PC and differentiate PHPT-PC from benign causes of PHPT preoperatively. Preoperative suspicion of malignancy is essential to guarantee the best course of treatment for patients. Although limited for size and follow-up, the excellent outcome of our series seems to support the value of both surgery extension and risk class according to the Schulte classification as possible prognostic factors for recurrence.

The Use and Benefit of Adjuvant Radiotherapy in Parathyroid Carcinoma: A National Cancer Database Analysis

Background

The routine use of external beam radiotherapy (EBRT) is not recommended for parathyroid carcinoma (PC). However, case series have demonstrated a potential benefit in preventing local recurrence with EBRT. We aimed to characterize the patient population treated with EBRT and identify any impact of EBRT on overall survival (OS) in parathyroid carcinoma.

Methods

Patients who underwent surgery for PC from 2004 to 2016 were identified from the National Cancer Database. Clinicopathologic variables and OS were compared between patients based on treatment with EBRT. Multivariable logistic and Cox regression models were performed with propensity scores and inverse-probability-weighting (IPW) adjustment to reduce treatment-selection bias in the OS analysis.

Results

A total of 885 patients met the inclusion criteria, with 126 (14.2%) undergoing EBRT. Demographics were similar between the two cohorts (EBRT vs. no EBRT). However, patients treated with EBRT had a higher frequency of regionally extensive disease, nodal metastases, and residual microscopic disease (all p < 0.05). On multivariable analysis, Black race, regional tumor extension, nodal metastasis, and treatment at an urban facility were independently associated with EBRT. The 5-year OS was 85.3% with a median follow-up of 60.8 months. EBRT was not associated with a difference in OS in crude, multivariable, or IPW models. More importantly, 10.5% of patients with completely resected localized disease (M0, N0 or Nx) underwent EBRT without a benefit in OS (p = 0.183).

Conclusions

EBRT is not associated with any survival benefit in the treatment of PC. Therefore, it may be overutilized, particularly in patients with localized disease and complete surgical resection.

Clinical Presentation, Treatment, and Outcome of Parathyroid Carcinoma: Results of the NEKAR Retrospective International Multicenter Study

OBJECTIVE

In this retrospective cohort study, we describe the clinical presentation and workup of parathyroid carcinoma (PC) and determine its clinical prognostic parameters. Primary outcome was recurrence free survival.

SUMMARY BACKGROUND DATA

PC is an orphan malignancy for which diagnostic workup and treatment is not established.

METHODS

Eighty-three patients were diagnosed with PC between 1986 and 2018. Disease-specific and recurrence-free survivals were estimated with the Kaplan-Meier method. Risk factors for recurrence were identified by binary logistic regression with adjustment for age and sex. Thirty-nine tumors underwent central histopathological review.

RESULTS

Renal (39.8%), gastrointestinal (24.1%), bone (22.9%), and psychiatric (19.3%) symptoms were the most common symptoms. Surgical treatment was heterogeneous [parathyroidectomy [PTx)] alone: 22.9%; PTx and hemithyroidectomy: 24.1%; en bloc resection 15.7%; others 37.3%] and complications of surgery were frequent (recurrent laryngeal nerve palsy 25.3%; hypoparathyroidism 6%). Recurrence of PC was observed in 32 of 83 cases. In univariate analysis, rate of recurrence was reduced when extended initial surgery had been performed (P = 0.04). In multivariate analysis low T status [odds ratio (OR) = 2.65, 95% confidence interval (CI) 1.02-6.88, P = 0.045], N0 stage at initial diagnosis (OR = 6.32, 95% CI 1.33-30.01, P = 0.02), Ki-67 <10% (OR = 14.07, 95% CI 2.09-94.9, P = 0.007), and postoperative biochemical remission (OR = 0.023, 95% CI 0.001-0.52, P = 0.018) were beneficial prognostic parameters for recurrence-free survival.

CONCLUSION

Despite a favorable overall prognosis, PC shows high rates of recurrence leading to repeated surgery and postoperative recurrent laryngeal nerve palsy and hypoparathyroidism. In view of the reduced recurrence rate in cases of extended surgery, ipsilateral completion surgery may be considered when PC is confirmed.

Parathyroid cancer: An update

Parathyroid cancer (PC) is a rare malignant tumor which comprises 0.5-5% of patients with primary hyperparathyroidism (PHPT). Most of these cancers are sporadic, although it may also occur as a feature of various genetic syndromes including hyperparathyroidism-jaw tumor syndrome (HPT-JT) and multiple endocrine neoplasia (MEN) types 1 and 2A. Although PC is characterized by high levels of serum ionized calcium (Ca) and parathyroid hormone (PTH), the challenge to the clinician is to distinguish PC from the far more common entities of parathyroid adenoma (PA) or hyperplasia, as there are no specific clinical, biochemical, or radiological characteristic of PC. Complete surgical resection is the only known curative treatment for PC with the surgical approach during initial surgery strongly influencing the outcome. In order to avoid local recurrence, the lesion must be removed en-bloc with clear margins. PC has high recurrence rates of up to 50% but with favorable long-term survival rates (10-year overall survival of 60-70%) due to its slow-growing nature. Most patients die not from tumor burden directly but from uncontrolled severe hypercalcemia. In this article we have updated the information on PC by reviewing the literature over the past 10 years and summarizing the findings of the largest series published in this period.

Parathyroid Carcinoma-An Experience of the Enigma Over 10 Years

INTRODUCTION

Parathyroid carcinoma (PC) is an uncommon clinical entity. Identification and appropriate treatment of PC remains a challenge. In this study, we explore clinico-radiological features suggestive of PC, the utility of Castleman's histopathological criteria for the diagnosis of PC and discuss the MD-Anderson prognostic stratification system for PC.

METHODS

Retrospective analysis (case series) of patients who were treated at our tertiary oncology institution between January 2009 and December 2018 with an eventual diagnosis of PC.

RESULTS

The study group comprised 15 patients. The most common presentation was related to the musculoskeletal system (n = 9, 60%). In one of the cases, ultrasound features were recorded to be suspicious of PC. The highest histopathological correlation with PC was found with capsular and vascular invasion (n = 12, 80%). The primary tumor was found in inferior parathyroid glands in most cases (n = 12, 80%). The average tumor size was 2.47 cm. Six patients (40%) received adjuvant radiotherapy (RT). Three patients (20%) developed recurrence, all having distant metastasis. Overall survival (OS) at 3 years was 92.31% and disease-free survival (DFS) of 76.61%.

CONCLUSION

The presence of certain features on ultrasonography might suggest PC preoperatively. Among Castleman's criteria, capsular invasion and vascular invasion had a maximum association with PC in our series. At present, there is no evidence to routinely give adjuvant RT to all patients with PC.

Using a Novel Diagnostic Nomogram to Differentiate Malignant from Benign Parathyroid Neoplasms

We sought to develop an immunohistochemical (IHC) tool to support the diagnosis of parathyroid carcinoma (PC) and help differentiate it from atypical parathyroid neoplasms (atypical) and benign adenomas. Distinguishing PC from benign parathyroid neoplasms can be challenging. Many cases of PC are histopathologically borderline for definitive malignancy. Recently, individual IHC biomarkers have been evaluated to aid in discrimination between parathyroid neoplasms. PC, atypical parathyroid neoplasms, and parathyroid adenomas treated at our institution from 1997 to 2014 were studied retrospectively. IHC analysis was performed to evaluate parafibromin, retinoblastoma (RB), protein gene product 9.5 (PGP9.5), Ki67, galectin-3, and E-cadherin expression. Receiver operating characteristic (ROC) analysis and multivariable logistic regression model for combinations of biomarkers were evaluated to classify patients as PC or atypical/adenoma. A diagnostic nomogram using 5 biomarkers was created for PC. Sixty-three patients were evaluated. The percent staining of parafibromin (p < 0.0001), RB (p = 0.04), Ki67 (p = 0.02), PGP9.5 (p = 0.04), and Galectin-3 (p = 0.01) differed significantly in the three diagnostic groups. ROC analysis demonstrated that parafibromin had the best performance in discriminating PC from atypical/adenoma; area under the curve (AUC) was 81% (cutoff, 92.5%; sensitivity rate, 64%; specificity rate, 87%). We created a diagnostic nomogram using a combination of biomarkers; AUC was 84.9% (95% confidence interval, 73.4-96.4%). The optimism-adjusted AUC for this model was 80.5% (mean absolute error, 0.043). A diagnostic nomogram utilizing an immunoexpression, a combination of immunohistochemical biomarkers, can be used to help differentiate PC from other parathyroid neoplasms, thus potentially improving diagnostic classification.

Comprehensive Genomic Characterization of Parathyroid Cancer Identifies Novel Candidate Driver Mutations and Core Pathways

CONTEXT

Elucidating the genomic landscape of sporadic parathyroid carcinoma (PC) has been limited by low tumor incidence.

OBJECTIVE

Identify driver mutations of sporadic PC and potential actionable pathways.

METHODS

Patients undergoing surgical resection for sporadic PC between 1980 and 2016 at MD Anderson Cancer Center were identified. Patients with sporadic PC according to World Health Organization diagnostic criteria and with available formalin-fixed, paraffin-embedded (FFPE) PC tumor tissue were included and their clinical data analyzed to assess extent of disease. Patients with parathyroid tumors of uncertain malignancy or atypical parathyroid neoplasms were excluded. Thirty-one patients meeting diagnostic criteria had available tissue for analysis. FFPE PC tumors were subjected to DNA extraction and next-generation whole-exome sequencing. All variant calls are single-algorithm only. Twenty-nine samples passed quality assurance after DNA extraction.

MAIN OUTCOME MEASURES

Somatic or private germline mutations present in sporadic PC and identification of pathways involved in tumorigenesis.

RESULTS

We identified 35 genes with considerable mutational load; only eight genes were previously identified in other PC cohorts. These genes mediate critical processes, including chromosome organization, DNA repair, and cell cycle regulations. Gene mutations involved in MAPK signaling and immune response are also heavily implicated. These findings are limited by inherent molecular artifacts in FFPE tissue analysis and the absence of matched germline DNA. Additionally, variant calls are only single algorithm and may include false-positive/negative calls.

CONCLUSION

We identified 33 candidate driver genes of sporadic PC, in addition to previously known driver genes CDC73 and MEN1.

Hypercalcemia and cancer: Differential diagnosis and treatment

Incidentally detected hypercalcemia usually presents in an indolent manner and is most likely caused by primary hyperparathyroidism. In contrast, hypercalcemia in the patient with a history of cancer presents in a wide range of clinical settings and may be severe enough to warrant hospitalization. This form of hypercalcemia is usually secondary to hypercalcemia of malignancy and can be fatal. Hypercalcemia of malignancy is most commonly mediated by tumoral production of parathyroid hormone-related protein or by cytokines activating osteoclast degradation of bone. The initial workup, differential diagnoses, confirmatory laboratory testing, imaging, and medical and surgical management of hypercalcemia are described in the patient with cancer.

Characterizing parathyroid carcinomas and atypical neoplasms based on the expression of programmed death-ligand 1 expression and the presence of tumor-infiltrating lymphocytes and macrophages

BACKGROUND

Four distinct tumor microenvironments have been proposed based on the expression of programmed death-ligand 1 and the presence of tumor-infiltrating lymphocytes: immunotype I (adaptive resistance, tumor-infiltrating lymphocytes+ and programmed death-ligand 1+); immunotype II (immunologic ignorance, tumor-infiltrating lymphocytes- and programmed death-ligand 1-); immunotype III (intrinsic induction; tumor-infiltrating lymphocytes- and programmed death-ligand 1+); and immunotype IV (tolerance, tumor-infiltrating lymphocytes+ and programmed death-ligand 1-). These subtypes may predict tumor response to immunotherapy. We hypothesized that parathyroid neoplasms may have tumor immunogenic expression that can later be used to guide treatment.

METHODS

We assessed retrospectively the immunohistochemical expression of programmed death-ligand 1 and the presence of tumor-infiltrating lymphocytes (CD3+ and CD8+) and macrophages (CD68+) in parathyroid carcinomas and in atypical parathyroid neoplasms treated at the M. D. Anderson Cancer Center from 1996 to 2016. Using intratumoral digital image analysis, the programmed death-ligand 1 H score was calculated with a standardized formula for predominant staining. The tumor-infiltrating lymphocytes per square millimeter of intratumoral areas were quantified.

RESULTS

Within 30 specimens (17 parathyroid carcinomas and 13 atypical parathyroid neoplasms), there was no difference in the median programmed death-ligand 1 H score between the two groups (P = .57). Four parathyroid carcinoma cases had programmed death-ligand 1 H scores ≥1 associated with CD3+ and CD8+ tumor cell density; 2 of them had distant metastases. Parathyroid carcinomas had a lesser median CD3+ density (P = .04) and a lesser median CD8+ density (P =.07) than did atypical parathyroid neoplasms. Median CD68+ density did not differ between groups (P = .22).

CONCLUSION

Parathyroid carcinomas tended to have immune-ignorant and immune-tolerant microenvironments within the neoplasm (immunotypes II and IV). Of the parathyroid carcinoma microenvironments, 17 had patterns of programmed death-ligand 1 and tumor-infiltrating lymphocytes expression (immunotype I), suggesting possible benefit from immunotherapy. In addition, both parathyroid carcinomas and parathyroid neoplasms expressed CD68+. Further exploration of these potential biomarkers as a target in cancer therapies is needed.