Introduction: The aim of this study was to determine the frequency and types of accompanying malignancies in Turkish subjects with differentiated thyroid cancer (DTC) residing in the northern region of Cyprus.
Subjects and methods: We retrospectively analysed 567 subjects with a diagnosis of DTC in the Departments of Endocrinology and Nuclear Medicine.
Results: Four hundred and forty-eight (79%) were females and 119 (21%) were males. A total of 17 subjects (2.9%) had an accompanying second malignancy other than DTC. Sixteen were females (94.2%) and one was male (5.8%). The mean age was 46.3 years for subjects with DTC being the only malignancy and 54.76 years for those with accompanying malignancies (P<0.05). Out of these 17 subjects 14 had classical papillary thyroid cancer (PTC), two had PTC follicular variant, and one had follicular thyroid cancer. All subjects received radioactive iodine for remnant ablation. The secondary malignancies were breast cancer in nine subjects (52.9%), endometrium cancer in two subjects (11.7%) and acute lymphoblastic leukemia, Hodgkin lymphoma, lung cancer, malignant melanoma, and gastrointestinal stromal tumour in one subject each. In 11 subjects DTC developed secondarily, in five subjects DTC developed first and in one subject DTC and the other malignancy developed synchronously.
Conclusion: The rate of accompanying malignancies in DTC was 2.9%. Classical PTC was the most frequent tumour type accompanying other malignancies (82.3%). DTC was observed four times higher in female subjects compared to male subjects. The role of gender was higher in those with accompanying malignancies. The most frequently observed accompanying malignancy was breast cancer leading by far. Only five subjects had developed a malignancy after the diagnosis of DTC and 12 subjects had a diagnosed malignancy before DTC. Thus we believe the role of RAI remnant ablation for secondary malignancy development is none or minimal.