Second primary cancer prevalence in differentiated thyroid cancer patients and correlation with thyroid primary tumor stage: A population-based cohort study in Iran

Introduction: Thyroid cancer is the most common endocrine malignancy. This often involves the middle-aged and active population, typically younger compared to those with other types of cancers. Some people with thyroid cancer may develop secondary malignancy. The reason for this is not well understood. This study was designed to evaluate the prevalence of second primary cancers in patients with differentiated thyroid cancer and its probable relationship with the severity of treatment and staging of the primary tumor.Methods: Among ۲۶۳۸ patients who underwent thyroidectomy between ۱۹۹۶ and ۲۰۱۸, we checked cases who suffered from non-thyroidal second primary cancers before, during, or after the diagnosis of thyroid cancer. Forty-nine patients met the criteria and were included in the study. The information was gathered from the medical records and supplemented by direct communication with the patients. The Data was then analyzed using appropriate statistical test with   SPSS version ۲۲, considering a P-value of ۰.۰۵ was considered as significant.Results: Out of the ۲۶۳۸ checked records reviewed, ۴۹ patients (۱.۸۵%) were found to have second primary cancers with ۷۵.۵% being female. One patient had two concurrent second primary cancers, while the remaining ۴۸ patients had a single second primary cancer. Most of the thyroid cancers were papillary (۸۹.۸%, ۴۴ cases), with the others remaining cases being follicular type. Stage ۲, according to the ۸th AJCC staging system, was the most common (۵۰%), followed by stage ۱ (۳۶.۸%) among the primary staging categories. Breast cancer was the most prevalent (۱۷ cases), followed by hematologic malignancies (۸ cases) and GI tract cancers (۸ cases). Conclusion: The findings revealed a significant increase in the number of breast cancers in patients with the differentiated thyroid cancer (DTC), which was not observed for other malignancies.

کلیدواژه ها:

Differentiated thyroid cancer ، Second primary cancer ، Tumor staging ، Malignancy