Multiple primary cancers of the esophagus and thyroid gland.

The occurrence of multiple primary cancers in the aerodigestive tract is a well known phenomenon that has been explained by the concept of 'field carcinogenesis'. Metachronous or synchronous esophageal cancer has usually been identified in patients with head and neck cancer, gastric cancer or colon cancer. The incidence of multiple primary cancers of the esophagus and thyroid gland is very low. We treated four patients with synchronous cancers of the cervical esophagus and the thyroid gland. Histologically, all of the esophageal cancers were squamous cell carcinomas. Thyroid cancers were evaluated as papillary carcinoma or follicular carcinoma. Both the esophageal cancer and the thyroid cancer frequently metastasized to lymph nodes. All patients had multiple lymph nodes metastasis from the esophageal or the thyroid cancer. In one patient, both the esophageal and the thyroid cancers were detected in the same lymph node. Three of four patients died from recurrence of esophageal cancer. The prognosis of these patients was poor. In the treatment of esophageal carcinoma, cancers of other organs including the thyroid gland should be carefully investigated.