Time to Recurrence as a Prognostic Factor in Parathyroid Carcinoma

Abstract

Background: Parathyroid carcinoma (PC) is a rare and challenging disease without clearly understood prognostic factors. Adequate management can improve outcomes. Characteristics of patients treated for PC over time and factors affecting prognosis were analyzed.

Methods: Retrospective cohort study including surgically treated patients for PC between 2000 and 2021. If malignancy was suspected, free-margin resection was performed. Demographic, clinical, laboratory, surgical, pathological, and follow-up characteristics were assessed.

Results: Seventeen patients were included. Mean tumor size was 32.5 mm, with 64.7% staged as pT1/pT2. None had lymph node involvement at admission, and 2 had distant metastases. Parathyroidectomy with ipsilateral thyroidectomy was performed in 82.2%. Mean postoperative calcium levels were different between patients who developed recurrence vs those who did not (P = .03). Six patients (40%) had no recurrence during follow-up, 2 (13.3%) only regional, 3 (20%) only distant, and 4 (26.6%) both regional and distant. At 5 and 10 years, 79% and 56% of patients were alive, respectively. Median disease-free survival was 70 months. Neither Tumor, Nodule, Metastasis system nor largest tumor dimension (P = .29 and P = .74, respectively) were predictive of death. En bloc resection was not superior to other surgical modalities (P = .97). Time between initial treatment and development of recurrence negatively impacted overall survival rate at 36 months (P = .01).

Conclusion: Patients with PC can survive for decades and have indolent disease course. Free margins seem to be the most important factor in initial surgery. Recurrence was common (60%), but patients with disease recurrence within 36 months of initial surgery had a lower survival rate.

Keywords: management; outcomes; parathyroid carcinoma; prognosis; survival.

Figure 1.

Tukey box plot of total calcium (A) and PTH (B) pattern after initial treatment according to recurrent disease or not.

Figure 2.

Kaplan-Meier curves for overall vs disease-free survival.

Figure 3.

Comparison of Kaplan-Meier survival curves according to initial pT stage, based on the 8th edition of the TNM (A), tumor size (B), and the type of surgery initially performed (C).

Figure 4.

Comparison of Kaplan-Meier curves for survival between patients who had vascular invasion in the pathology report vs patients who did not.

Figure 5.

Comparison of Kaplan-Meier curves for survival between patients who developed recurrent disease up to (A) 24 months and (B) 36 months of follow-up vs patients who did not develop recurrence at follow-up.