Definition: Adenocarcinoma is a type of cancer that occurs in the cells within the body's tissues, such as the skin, lungs, prostate gland, or stomach. The term "adeno" means "adenomyosis," which refers to the condition of a mother's uterus becoming inflamed and swollen due to an infection. Adenocarcinoma is typically caused by mutations in genes that control cell division and growth, leading to abnormal cells growing uncontrollably. It is usually diagnosed through a biopsy or imaging study, which involves taking tissues from the tumor or tissue samples used for diagnosis. Treatment options depend on the specific type of adenocarcinoma, but can often involve chemotherapy, radiation therapy, surgery, or combination therapy.