Which of the following statements concerning carcinoma of the esophagus is true?

Carcinoma of the esophagus occurs primarily in the sixth and seventh decades of life in a male:female ratio of 3:1. Although the cause is unknown, alcohol, tobacco, and dietary factors have been implicated as causative agents. A high incidence is reported in patients with corrosive esophagitis. The malignant tumors arising in the esophagus are usually squamous cell carcinomas except those involving the esophagogastric junction, which are usually adenocarcinomas. Even though squamous cell carcinomas are weakly radiosensitive, surgical extirpation affords reasonable, if short-term, palliation. Some authorities recommend radiotherapy for palliation alone or in combination with surgery to treat this lesion. Adenocarcinomas are not particularly radiosensitive and surgical treatment is generally employed. Following resection for esophageal carcinoma among the highly select group of patients whose tumors are still resectable when the diagnosis is made, survival is only about 14% at 5 years. The overall 5-year survival is under 5%.