Aim: To compare the frequency of main histopathological characteristics, 131І thyroid radiation doses, invasive properties and post-operative follow-up of patients of different age groups with potentially radiogenic papillary thyroid carcinoma (PTC) with the presence and absence of oncocytic changes in tumor cells.
Materials and methods: PTC removed in 483 patients from high risk age-group for radiogenic thyroid cancer development (children and adolescents at the time of Chornobyl accident who lived in the northern regions of Ukraine: Kyiv, Zhytomyr, and Chernihiv regions) have been studied microscopically.
Results: The frequency of PTC with the presence of oncocytic changes (OCh) in tumor cells increased significantly with increasing of patients' age at the time of surgery: from 8.3% in children 4-14 years old to 54.3% in adults 39-48 years old (ptrend < 0.0001). The presence of such changes is associated with papillary and solid-trabecular dominant tumor growth pattern in more than 90% of cases in each age group. The mean 131І thyroid dose in the whole series of PTC patients with OCh was significantly lower compared to the same index in PTC patients without OCh (493.7 mGy and 765.8 mGy, respectively, p < 0.0001). In addition, regional metastases recurrences were revealed more frequently in patients with OCh in primary PTC compared with patients without OCh in primary tumor (7.2% vs 1.5%, p = 0.0022).
Conclusions: Significantly increasing age-trend of OCh in PTC of patients affected by the Chornobyl fallout and operated at age from 4 to 48 years, as well as opposite decreasing linear age-trend of 131І thyroid dose may reflect a gradual increase of sporadic PTCs frequency in the potentially radiogenic series with time elapsed since accident. The frequency of oncocytic insensitive to radioiodine therapy of lymph node metastases recurrences also increased with patients age and OCh availability in primary PTC.