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 develop- ment, to determine the frequency and the time of occurrence of malignant tumours in patients with pHPT, and to evaluate the charac- teristics 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 di- agnosis of pHPT. A higher percentage (87.5%) of simultaneous tumours was seen in the thyroid gland. No statistically significant differ- ences 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.