Increased incidence of papillary thyroid cancer detection among thyroidectomies in Greece between 1991 and 2006

Abstract

Objective: To examine existing evidence, trends and possible factors that may have affected the incidence of papillary thyroid cancer (PTC) among patients undergoing thyroidectomies in an iodine-sufficient population of Greece.

Study design: All histology records from the patients who had undergone thyroid surgery at the Department of Surgery Laiko Hospital, Athens, Greece from January 1991 to December 2006 were retrospectively analyzed. Records were placed in a database which included patients' demographics, history, and medical condition, clinical and surgical parameters.

Patients and methods: One thousand four hundred and twenty-six patients (265 males and 1161 females) had undergone thyroidectomy during the above period of time. All surgeons favoured total thyroidectomy with resection of pro- and paratracheal lymph nodes. Thyroid tumors were classified according to the WHO classification system and were staged according to the TNM staging system.

Results: In 278 patients, PTC was histologically diagnosed. From 1999 onwards, thyroid surgery shifted towards total thyroidectomy, while statistically significantly increased incidence of PTC and papillary microcarcinoma detection and decreased incidence of PTC greater than 10 mm detection in the whole population were noticed. Moreover, from 1999 onwards, smaller size of primary tumors, higher incidence of T1 tumors, lower incidence of T4 tumors, lower incidence of metastatically infiltrated peritracheal lymph nodes, higher incidence of stage I tumors and lower incidence of stage IV tumors were documented. Finally, a higher incidence of PTC in males, females and the whole population aged 51-70 years compared to the other age groups since 2003 was noticed.

Conclusion: The increased incidence of PTC clearly correlated to the increased incidence of papillary microcarcinoma detection, reflecting the proportion for total thyroidectomy as well as changes in the diagnostic approach boosted by more careful pathological examination, rather than the effect of environmental factors such as the Chernobyl accident. Whether the Chernobyl accident has any predisposing effect on the increased incidence of PTC remains to be proven.