Metastasis in ovarian cancer is very common in the abdomen, and occurs via exfoliation, where cancer cells burst through the ovarian capsule and are able to move freely throughout the peritoneal cavity. Ovarian cancer metastases usually grow on the surface of organs rather than the inside; they are also common on the omentum and the peritoneal lining. Cancer cells can also travel through the lymphatic system and metastasize to lymph nodes connected to the ovaries via blood vessels; i.e. the lymph nodes along the infundibulopelvic ligament, the broad ligament, and the round ligament. The most commonly affected groups include the paraaortic, hypogastric, external iliac, obturator, and inguinal lymph nodes. Usually, ovarian cancer does not metastasize to the liver, lung, brain, or kidneys unless it is recurrent disease; this differentiates ovarian cancer from many other forms of cancer.