Parathyroid cancer: biology and management

Abstract

A review of all reports in the literature of parathyroid carcinoma (PTC) was undertaken to define an optimal management strategy for this rare condition. PTC is uncommon and its etiology of PTC is largely unknown although patients with familial hyperparathyroidism, multiple endocrine neoplasia type 1 and irradiation to the head and neck are at increased risk for developing the disease. PTC occurs with equal frequency in both sexes and is usually diagnosed in the fifth decade. En bloc resection of the carcinoma and the adjacent structures in the neck is the surgical treatment and is associated with an 8% local recurrence rate and a long term overall survival rate of 89% (mean follow up 69 months). In contrast simple parathyroidectomy results in a 51% local recurrence rate and 53% long-term survival rate (mean follow up 62 months). Adverse prognostic factors for survival were initial management with simple parathyroidectomy alone, the presence of nodal or distant metastatic disease at presentation and non-functioning PTC.

Introduction

The first case of parathyroid carcinoma described by de Quevain [1] in 1904 was a patient with non-functioning cancer. Sainton and Millet [2] are credited with the first description of functioning carcinoma in 1933. However, parathyroid cancer remains an enigmatic neoplasm. Its rarity and the paucity of published series of patients in the literature have hampered our understanding of its natural history and prognostic factors. This has prevented a clear consensus emerging regarding its surgical and adjuvant treatment.

We have undertaken a review of all cases reported in the English language literature over the last 65 years [3], [4], [5]. Parathyroid carcinoma has been the subject of several reviews. Holmes et al. [3] reviewed 42 cases reported between 1933 and 1969 [2], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45] while Shane and Bilezikian [4] reviewed the 62 cases reported between 1969 and 1981 [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82]. Obara and Fujimoto [5] considered a further 163 patients reported between 1981 and 1990 [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100], [101], [102], [103], [104], [105], [106], [107], [108], [109], [110], [111], [112], [113], [114], [115], [116], [117], [118], [119], [120], [121], [122], [123], [124], [125], [126], [127], [128], [129], [130], [131], [132], [133], [134], [135], [136], [137], [138]. We have carefully reviewed all of these cases and added a further 94 reported between 1990 and January of 1999 [139], [140], [141], [142], [143], [144], [145], [146], [147], [148], [149], [150], [151], [152], [153], [154], [155], [156], [157], [158], [159], [160]. In addition to reviewing the published cases of PTC we also subjected those cases in whom sufficient information was available to survival analysis in order to more clearly define the prognostic factors and the optimal management strategy for this condition.

The aim of this investigation was to clarify our understanding of the biological behaviour of carcinoma of the parathyroid gland and, on the basis of this, make clear recommendations for the surgical and adjuvant management of this condition.