A 22-year-old woman goes to her physician for a routine exam…

A 22-year-old woman goes to her physician for a routine examination. A palpable nodule is found in the right lobe of her thyroid gland. No lymphadenopathy is noted. A chest x-ray shows no masses. A fine needle aspirate of the nodule is performed and cytologic examination reveals cells present consistent with a papillary carcinoma of the thyroid. There are no other family members affected by this disorder. She works as a secretary for an accounting firm part time and is earning a college degree. Which of the following findings would you consider most relevant in her past history to indicate a risk factor for this neoplasm?

An epidemiologic study is performed to determine risk factor…

An epidemiologic study is performed to determine risk factors for development of malignant neoplasms. A statistical analysis of pre-existing medical conditions is done. Some pre-existing conditions are observed to precede development of malignant neoplasms, while others do not. Which of the following conditions is most likely to be statistically unrelated to subsequent malignancy?