Peptic Ulcer Disease: This condition is a common cause of epigastric pain that can radiate to the back, especially if the ulcer is located posteriorly. The pain is often described as burning or gnawing and can be exacerbated by food or improved by antacids.

Gastroesophageal Reflux Disease (GERD): GERD can cause epigastric pain that may radiate to the back due to the reflux of stomach acid into the esophagus, irritating the esophageal mucosa.
Cholecystitis: Inflammation of the gallbladder can cause right upper quadrant or epigastric pain that may radiate to the back, especially if a stone is obstructing the cystic duct.
Pancreatitis: Both acute and chronic pancreatitis can cause severe epigastric pain that radiates to the back, often accompanied by nausea, vomiting, and elevated pancreatic enzymes.

Myocardial Infarction: Although less common, myocardial infarction can present with epigastric discomfort or pain radiating to the back, especially in women or diabetic patients, making it crucial not to miss this potentially life-threatening condition.
Aortic Dissection: This is a medical emergency where the inner layer of the aorta tears, causing severe pain that can be described as tearing or ripping and can radiate to the back. It often starts in the chest but can move downward.
Esophageal Rupture: A rupture of the esophagus can cause severe chest or epigastric pain radiating to the back, often accompanied by difficulty swallowing, vomiting, and signs of sepsis.

Splenic Artery Aneurysm: Although rare, an aneurysm of the splenic artery can cause left upper quadrant or epigastric pain radiating to the back, especially if it ruptures.
Gastric Cancer: Gastric cancer can present with epigastric pain that may radiate to the back, although this is less common and usually accompanied by other symptoms like weight loss and difficulty swallowing.
Mediastinitis: Inflammation of the tissues in the mediastinum can cause chest or epigastric pain radiating to the back, often due to an infection.