RET and p53 expression in thyroid follicular adenoma: a study of 52 cases with 14 years follow-up

Most previous studies on RET and p53 proteins have focused on thyroid papillary carcinoma. We investigated the role of RET and p53 protein expressions using immunohistochemistry on 52 cases of thyroid follicular adenomas and studied the follow-up records of these patients. The range of follow-up period was 3 to 14 years. The patients were between 15 and 71 years of age with a median age of 34.5 years. There were 46 females and 6 males. Except for 3 cases, all patients were Malays. The minimum volume of the tumour was 1000 mm3 and the maximum was 512,000 mm3 with a median of 270,000 mm3. Eleven (21.2%) cases showed RET expression. RET expression was not statistically significant when cross-tabulated against sex (p = 0.322), ethnicity (p = 0.518), age (p = 0.466) and symptom duration (p = 0.144). Six (11.5%) of 52 cases showed p53 immunopositivity. p53 expressions were also not significantly correlated to the clinical parameters above. There was no correlation between RET and p53 protein expressions. The only statistically significant finding was the association of tumour volume with duration of symptoms (p = 0.05). All patients are alive at the time of writing. 3 had recurrent goitre, 2 of these were diagnosed as colloid goitre while the third was a follicular lesion. One patient suffered from depression requiring anti-depressant treatment. In conclusion, unlike papillary carcinoma in which the roles of ret and p53 oncogenes are known, their roles in influencing the behaviour of follicular adenoma has not been ascertained.