Final answer:
Gastric cancer affects the stomach, and it is diagnosed using medical tools like blood tests, X-rays, CT scans, and endoscopy. Treatment and prognosis vary depending upon the organ affected by cancer.
Step-by-step explanation:
The organ affected in a diagnosis of gastric cancer is the stomach. Gastric cancer is a type of cancer that begins in the stomach, the muscular organ located in the upper part of the abdomen where the digestion of food starts. When a person is suspected of having cancer, medical diagnosis tools such as blood tests, X-rays, CT scans, and endoscopy are commonly utilized to detect the presence and extent of the disease. It is important to distinguish gastric cancer from other types of cancer, as the treatment and prognosis vary depending on the organ affected. For instance, whereas gastric cancer affects the stomach, other common cancers, such as lung, colon, and breast cancer, occur in different organs and are associated with different carcinogens.