A 76-year-old woman is complaining of a progressive swallowing disorder, predominantly when she eats solid foods. This sign is observed over the past 6 weeks. Sometimes she notes episodes of vomiting with solid vomitus. Swallowing is painless. She has lost 6 kg. Ten years ago she had a myocardial infarction. She permanently takes aspirin and long-acting nitrates, drinks alcohol in moderation, and smokes. Her skin is icteric, her neck is normal, the lymph nodes are not enlarged. The chest is normal. The cardiovascular system shows no marked changes. The liver is +3 cm. Make the right diagnosis: