The presentation of painless jaundice and weight loss in a 70-year-old male strongly suggests pancreatic cancer, particularly a tumor in the head of the pancreas causing biliary obstruction without inflammation or pain. This contrasts with gallstones or acute hepatitis, which typically cause pain or systemic symptoms. Chronic pancreatitis usually presents with recurrent abdominal pain rather than isolated painless jaundice. Early recognition is crucial as the tumor's location near the bile duct leads to obstructive jaundice, a hallmark sign aiding in diagnosis. Surgical resection (e.g., Whipple procedure) offers the best chance for cure, highlighting the importance of early detection.

Reference: Harrison's Principles of Internal Medicine, J. Larry Jameson et al., 20th Edition.