Peritoneal cancer (peritoneal carcinomatosis) is typically a secondary cancer that arises when cancer cells from other organs spread to the peritoneum (the lining of the abdominal cavity). The most common primary sources include gynecological cancers such as ovarian, uterine, and cervical cancers, as well as gastrointestinal system cancers like those of the colon, stomach, pancreas, gallbladder, and bile ducts. Breast and lung cancers can also spread to the peritoneum.

Rarely, primary peritoneal mesothelioma, a type of cancer originating directly from the peritoneum, can occur. Mesothelioma is strongly associated with asbestos exposure, and while these tumors are generally quite rare in the general population, familial cases have been observed in certain geographical regions where asbestos was widely used in the past, for instance, specific areas in Nevşehir.

Additionally, mucinous tumors originating in the appendix (mucinous appendiceal neoplasms) can lead to a widespread condition known as pseudomyxoma peritonei, characterized by the accumulation of gelatinous material on the peritoneal surface.