Adenocarcinoma is a type of cancer that forms in mucus-secreting glands throughout the body. It can occur in many different places in the body, and is most prevalent in the following cancer types:1  Lung cancer: Non-small cell lung cancer accounts for 80 percent of lung cancers, and adenocarcinoma is the most common type. Surgery: Adenocarcinoma is often treated with surgical removal of cancerous glandular tissue, as well as some surrounding tissue. 2  Minimally invasive surgical treatment methods can help to reduce healing time and minimize the risk of infection after surgery.