C78: Secondary malignant neoplasm of respiratory and digestive organs

C78 refers to a group of conditions called secondary malignant neoplasms of respiratory and digestive organs. These conditions occur when cancer cells spread from the original (primary) tumor and form a new tumor in the respiratory or digestive systems. The respiratory system includes organs like the lungs and windpipe, and the digestive system includes organs like the stomach, liver, or intestines. When cancer spreads in this way, it's known as metastasis. Symptoms can vary depending on where the new tumor forms, but common ones include trouble breathing, persistent cough, abdominal pain, or unexplained weight loss. The progression of these conditions can also vary, but they are generally serious and can lead to severe health problems. These conditions often arise from cancers that are aggressive or not caught early.