Primary hyperparathyroidism: review and recommendations on evaluation, diagnosis, and management. A Canadian and international consensus

The purpose of this review is to assess the most recent evidence in the management of primary hyperparathyroidism (PHPT) and provide updated recommendations for its evaluation, diagnosis and treatment. A Medline search of "Hyperparathyroidism. Primary" was conducted and the literature with the highest levels of evidence were reviewed and used to formulate recommendations. PHPT is a common endocrine disorder usually discovered by routine biochemical screening. PHPT is defined as hypercalcemia with increased or inappropriately normal plasma parathyroid hormone (PTH). It is most commonly seen after the age of 50 years, with women predominating by three to fourfold. In countries with routine multichannel screening, PHPT is identified earlier and may be asymptomatic. Where biochemical testing is not routine, PHPT is more likely to present with skeletal complications, or nephrolithiasis. Parathyroidectomy (PTx) is indicated for those with symptomatic disease. For asymptomatic patients, recent guidelines have recommended criteria for surgery, however PTx can also be considered in those who do not meet criteria, and prefer surgery. Non-surgical therapies are available when surgery is not appropriate. This review presents the current state of the art in the diagnosis and management of PHPT and updates the Canadian Position paper on PHPT. An overview of the impact of PHPT on the skeleton and other target organs is presented with international consensus. Differences in the international presentation of this condition are also summarized.

Multicentre study comparing aggressive behaviour of familial non-medullary thyroid carcinoma and sporadic thyroid cancer

Background

Familial non-medullary thyroid cancer represents about 5 per cent of all thyroid cancers of follicular cell origin. Whether familial non-medullary thyroid cancer is more aggressive than sporadic thyroid cancer is controversial.

Methods

Each patient with familial non-medullary thyroid cancer was matched with three controls for age, sex and tumour node metastasis (TNM) stage of disease. Possible prognostic factors were compared in relation to recurrence, metastases and mortality rate in both groups. Univariate analysis was performed using contingency table analysis and McNemar's χ2 test for paired measurements. Multivariate analysis was used to evaluate factors significant in univariate analysis.

Results

Forty-eight cases (ten men) and 144 matched controls (30 men) were analysed with a mean follow-up of 102 and 94 months respectively. The mean age was 39 years for cases and 46 years for controls. Some 29 per cent of the cases and 12 per cent of the controls had history of prior or coexistent benign thyroid disease (P < 0·05). Ninety-four per cent of cases and 90 per cent of controls had papillary cancers; the remainder were Hurthle cell cancers. Based on TNM staging, there were 66 per cent stage I, 21 per cent stage II and 13 per cent stage III tumours in the familial non-medullary thyroid cancer group; the distribution was similar in the control group. Modified radical neck dissection was performed in 42 per cent of cases and 22 per cent of controls. Multifocal or bilateral disease was seen in 75 per cent of cases and 41 per cent of controls (P < 0·05); 35 per cent of cases and 16 per cent of controls had at least one recurrence (P < 0·05). Ten per cent of cases and 2 per cent of controls developed distant metastases (P < 0·05). Six per cent of cases but no controls died from thyroid cancer (P < 0·05). In patients with familial non-medullary thyroid cancer aged over 45 years (n = 14), distant metastases affected four, of whom three died. In multivariate analysis, age was the only significant variable that affected the disease outcome (P < 0·01).

Conclusion

Familial non-medullary thyroid cancer is more aggressive than sporadic thyroid cancer and is associated with increased recurrence, metastasis and death, especially in patients over 45 years of age.

Laparoscopic nephrectomy and autotransplantation for severe iatrogenic ureteral injuries

OBJECTIVES

To evaluate the efficacy of laparoscopic nephrectomy with autotransplantation in cases of severe proximal ureteral damage. Many patients with complex proximal ureteral injuries have good functional renal parenchyma and wish to salvage their kidney. Autotransplantation is a viable alternative to nephrectomy in these frustrating situations.

METHODS

Two patients, aged 32 and 36 years, underwent laparoscopic nephrectomy and autotransplantation for treatment of severe proximal ureteral injuries. The injuries included a ureteropelvic junction avulsion and a proximal ureteral avulsion, respectively. Both patients had good functional renal parenchyma. A transperitoneal laparoscopic approach was used, and the kidney was removed by way of a Gibson incision.

RESULTS

The procedures were successful, with immediate return of renal function in both patients. A pyeloureterostomy to the native distal ipsilateral ureter was required in one and a direct ureterovesical anastomosis was performed in the other. In the 2 patients, the warm ischemia time was 4.5 and 4 minutes, the transplant operative time 175 and 150 minutes, and the estimated blood loss 150 and 75 mL, respectively. No intraoperative complications occurred. At follow-up, the kidneys were functional, and the patients had returned to their normal activity.

CONCLUSIONS

Laparoscopic nephrectomy with autotransplantation is an excellent alternative to nephrectomy or bowel interposition in patients with proximal ureteral loss, irrespective of the contralateral renal function. This procedure is associated with acceptable morbidity and preserves the renal function. This approach is desirable in those patients who have had complications from other surgical procedures and are otherwise facing the loss of a normally functioning kidney.

The role of growth factors in proliferation and invasion of thyroid cancer

A growing literature has established the close association between tumor progression and growth regulatory aberrations in cancer cells. Most studies have focused on the phenomenon, that advanced tumors or metastases have lost the sensitivity to growth inhibitors. Metastasis are the primary cause of death in patients with differentiated thyroid cancer. Proliferation and differentiation of the thyroid was supposed to be under the major control of only a single hormone (thyroid stimulating hormone). However, we and others have shown that a complex network of various growth factors regulates growth and invasion of thyroid cancer cells. Our findings highlight two aberrations of growth regulation which may favour progression of malignancy and acquisition of metastatic competence: i) resistence to growth factor inhibitors and ii) growth autonomy of metastatic thyroid cancer cells.

A novel multicolor hybridization scheme applied to localization of a transcribed sequence (D10S170/H4) and deletion mapping in the thyroid cancer cell line TPC-1

The sequence-tagged site (STS) D10S170, also referred to as H4, is a gene of unknown function. Its 5' end was found fused to the catalytic domain of the RET protooncogene to generate RET/PTC 1, the most common form of PTC oncogenes in human papillary thyroid carcinoma. This gene has previously been assigned to a very large genomic region, 10q11.22-->q22.1. Here, we describe the application of a novel hybridization scheme to the physical and genetic mapping of D10S170. First, we selected a homologous large-insert DNA clone from a human P1 library by filter hybridization and confirmed its authenticity by Southern blot analysis. Triple-color fluorescence in situ hybridization (FISH) experiments mapped this clone to l0q21.2-->q21.3. "Binning" experiments were performed using a quadruple-color FISH approach aimed toward placing the gene in a genetic interval defined by differentially labeled P1 DNA probes containing known polymorphic markers. We found that multicolor FISH greatly expedites chromosomal mapping. Finally, we applied our FISH approach to determine the extent of deletion involving this locus (D10S170) in a papillary thyroid cancer cell line, TPC-1.

Molecular and cytogenetic characterization of a t(1;10;21) translocation in the human papillary thyroid cancer cell line TPC-1 expressing the ret/H4 chimeric transcript

BACKGROUND

Activation of the ret proto-oncogene by three different chromosomal rearrangements occurs in up to 25% of papillary thyroid carcinomas. We developed a rapid screening technique to detect ret rearrangements in human interphase and metaphase cells on the basis of multicolor fluorescence in situ hybridization (FISH) of locus-specific DNA probes.

METHODS

DNA from individual clones representing the respective ends of a yeast artificial chromosome (YAC) contig spanning the entire ret gene locus were labeled with either digoxigenin (visualized in red) or biotin (green) and hybridized to normal human lymphocytes and the papillary thyroid cancer cell line TPC-1 expressing the ret/H4 chimeric transcript. Further detailed analysis was performed with whole chromosome painting probes and locus-specific probes (YACs, P1s, DNA repeat probes) on tumor metaphase spreads.

RESULTS

Hybridization of the YACs to unrearranged ret loci in normal human lymphocyte interphase nuclei showed two yellow domains because of probe overlap. Hybridization to TPC-1 interphase nuclei showed one yellow domain, and 1 red and 1 green domain separated by a large physical distance. Further analysis of metaphase spreads revealed a complex translocation t(1;10;21)(1pter > 1q31::21q22.1 > 21qter; 10q11.2 > 10pter::1q31 > 1qter; 21pter > 21q22.1;;10q21.2 > 10q11.2::10q21.2 > 10qter) and loss of the H4 gene locus on the nontranslocated chromosome 10.

CONCLUSIONS

Break point spanning probes can reliably detect ret rearrangements in interphase nuclei. Locus-specific and whole chromosome painting probes can be used to further characterize complex rearrangements by fluorescence in situ hybridization to metaphase spreads. The papillary thyroid cancer cell line TPC-1 carries the paracentric inversion 10q, inv(10)(q11.2q21) and a complex t(1; 10; 21) translocation. Deletion of the H4 gene on the chromosome 10 not involved in the t(1; 10; 21) translocation suggests lack of normal H4 expression in the TPC-1 cell line. Further studies will have to address the role of the H4 gene product in tumor genesis and progression.