Step 1: Understand cancer classification.
Cancers are classified based on the type of tissue from which they originate.
Step 2: Define carcinoma.
Carcinoma is a cancer that originates from epithelial tissues, which cover body surfaces and organs.
Step 3: Define sarcoma.
Sarcoma arises from connective tissues like bone, muscle, and cartilage.
Step 4: Define leukemia and lymphoma.
Leukemia is cancer of blood-forming tissues, while lymphoma affects lymphatic system.
Step 5: Key identification point.
Epithelial tissue-specific cancers are always classified as carcinoma.
Step 6: Conclusion.
Thus, epithelial cancer is called carcinoma.