Previous, simultaneous, or subsequent occurrence of malignant tumours in patients with primary hyperparathyroidism: a closer look at the single-tertiary-centre cases.

Introduction: Our aims were to explore the relationship between primary hyperparathyroidism (pHPT) and malignant tumour development, to determine the frequency and the time of occurrence of malignant tumours in patients with pHPT, and to evaluate the characteristics of pHPT in these patients.

Material and methods: This retrospective cohort study included consecutive individuals who were diagnosed with pHPT aged 18 years or older in a university hospital during a 7-year period. A total of 198 patients with pHPT were reviewed retrospectively. Demographic, clinical, biochemical, radiologic findings, and histopathological diagnosis were collected from the electronic medical records of the hospital system.

Results: The mean age of the study population was 58 ± 13 years and was predominantly female (female/male: 162/36). There were 42 (21.2%) patients with malignant tumours. Five (12%) out of 42 patients had metachronous double malignancies. The most common 2 concurrent malignancies were breast (36.1%) and thyroid (17.0%). Sixty-eight per cent of the malignant tumours occurred before the diagnosis of pHPT. A higher percentage (87.5%) of simultaneous tumours was seen in the thyroid gland. No statistically significant differences were observed between patients with and without malignant tumours in terms of demographic, clinical, biochemical, radiological, and histopathological features. The median follow-up duration was 24 months after parathyroid surgery.

Conclusion: The results of this study revealed that pHPT was associated with various tumour types. The frequency of malignant tumours was 21.2%. Breast and thyroid cancers were the most common 2 cancers coexisting with pHPT. A large percentage of malignant tumours occurred before the diagnosis of pHPT. A higher percentage of simultaneous tumours was seen in the thyroid gland. pHPT patients with and without malignant tumours seemed to have similar characteristics.