Tumor involvement of the peritoneum-peritoneal carcinomatosis-is a heterogeneous form of cancer that had been generally regarded as a sign of systemic tumor disease and as a terminal condition. The multimodal treatment approach for patients with peritoneal carcinomatosis, which had been conceived and developed, consists of what is known as cytoreductive surgery, followed by hyperthermic intraperitoneal chemotherapy (HIPEC). Depending on the tumor mass as assessed intraoperatively and the histopathological differentiation, patients who undergo cytoreductive surgery and HIPEC have a significant survival benefit. Mean increases in the survival period ranging from six months to up to four years have now been reported. In view of the substantial logistic effort and the extent of the surgery involved, this treatment approach represents a major challenge both for patients and for surgical oncologists, as well as for the members of the overall interdisciplinary structure required, which includes oncology, anesthesiology and intensive care, psycho-oncology, and patient management. The surgical procedures alone may take 8-14 hr. The present paper provides an overview of the basis for the approach and the use of specialized classifications and quantitative prognostic indicators.