Nivolumab is a medication used in this clinical trial to help prevent the return of cancer in patients who have had surgery to remove esophageal or gastroesophageal junction cancer. It works by helping the immune system recognize and attack cancer cells.

Adenocarcinoma of the Esophagus – This is a type of cancer that begins in the glandular cells of the esophagus, which are responsible for producing mucus and other fluids. It typically occurs in the lower part of the esophagus and is often associated with a condition called Barrett’s esophagus. The disease progresses as the cancer cells grow and invade deeper layers of the esophagus and potentially spread to nearby lymph nodes and other organs. Symptoms may include difficulty swallowing, chest pain, and weight loss. Over time, the tumor can obstruct the esophagus, making it difficult to eat or drink.

Squamous Cell Carcinoma of the Esophagus – This cancer originates in the flat, thin cells lining the esophagus and is more common in the upper and middle parts of the esophagus. It is often linked to smoking and alcohol consumption. As the disease progresses, the cancer cells can invade deeper tissues and spread to other parts of the body. Symptoms may include difficulty swallowing, chest pain, and unintentional weight loss. The tumor can grow to block the esophagus, leading to further complications.

Adenocarcinoma of the Gastroesophageal Junction – This cancer occurs where the esophagus meets the stomach, known as the gastroesophageal junction. It often arises from Barrett’s esophagus, a condition where the normal lining of the esophagus changes due to acid reflux. The disease progresses as cancer cells invade surrounding tissues and may spread to lymph nodes and distant organs. Symptoms can include difficulty swallowing, chest pain, and weight loss. As the tumor grows, it can obstruct the passage of food, leading to nutritional issues.

Squamous Cell Carcinoma of the Gastroesophageal Junction – This is a rare type of cancer that occurs at the junction of the esophagus and stomach, originating from the squamous cells. It is less common than adenocarcinoma in this location and is associated with risk factors like smoking and alcohol use. The disease progresses as the cancer cells invade deeper layers and potentially spread to other parts of the body. Symptoms may include difficulty swallowing, chest pain, and weight loss. The tumor can grow to obstruct the gastroesophageal junction, causing further complications.