Question

Of 2,872 persons who had received radiation treatment in childhood because of an enlarged thymus, cancer of the thyroid developed in 24 and a benign thyroid tumor developed in 52. A comparison group consisted of 5,055 children who had received no such treatment (brothers and sisters of the children who had received radiation treatment). During the follow-up period, none of the comparison group developed thyroid cancer, but benign thyroid tumors developed in six. Calculate the relative risk for benign thyroid tumors: _____

Answer 1

Answer: People who have received radiation treatment are 15 times more likely to develop benign thyroid tumors relative to does who have not.

Explanation:

Relative risk of benign thyroid tumor = (52/2872)/(6/5055)

= 0.018/0.0012

= 15