Increase Cancer Risk in Patients with Primary Hyperparathyroidism

Introduction: Primary Hyperparathyroidism (PHPT) affects at least 1 in 1000 individuals and its incidence increases with age, with a peak incidence in the seventh decade of life. It is the third most common endocrine diagnosis. Several studies have identified a relationship between PHPT and an increased risk of developing malignancies such as breast, skin, colon, rectal, thyroid, prostate, and kidney cancers. The aim of this study was to report a cohort of patients with PHPT with concomitant cancer and compared them with PHPT without cancer. Methods: Retrospective study from a prospectively kept database of patients with PHPT treated by our group between January 2015 and July 2017. The operation performed by our group is, a minimally invasive radio-guided parathyroidectomy, which entails a bilateral neck exploration through a two-centimeter incision. The patients’ characteristics were obtained and analyzed from the electronic medical records. Patients without complete medical records were not included in our study. All data were collected in a non-identifiable fashion in accordance with the principles outlined in the declaration of Helsinki and as required for our institutional review board approval. Results and Discussion: A total of 63 patients with PHPT were included in our study. Eighty percent of our patients were females; the mean age at diagnosis was 56.7 years (range: 29 years to 77 years). There were 23 patients with concomitant cancer (36.5% of the cases). The most frequently encountered malignancy was breast cancer in 14.3% of the cases (nine patients), thyroid cancer 7.9% (five patients), and skin cancer 6.3% (two patients with melanoma, one with basal-cell carcinoma and another one with squamous cell cancer). We did not identify a clinical or statistical difference between the two groups. The patients’ demographics were very similar: gender (p=0.8), age (p=0.6), preoperative calcium levels (p=0.3), preoperative PTH levels (p=0.2), preoperative vitamin D levels (p=0.5) and preoperative urinary calcium levels (p=0.5). Conclusion: The available evidence at this time suggests a possible correlation between PHPT and malignancy. It remains to be clarified whether the risk is due to genetic predisposition to tumor development or a physiological associative effect. We recommend discussing with patients with a diagnosis of PHPT who are considering undergoing a parathyroidectomy about the possible increased risk of cancer seen in patients with PHPT. More studies are needed to determinate the exact relationship between the PHPT and the risk of developing cancer.