Quantitative prognostic indicators for carcinomatosis and sarcomatosis are essential in the management of peritoneal surface malignancy. This need is greatly accentuated as a new comprehensive therapeutic approach emerges. The assessment of tumor histopathology, prior surgical score, lesion size, and distribution (Gilly classification and peritoneal cancer index) and the completeness of cytoreduction scores are the tools that are currently in use. Although current assessments have greatly facilitated clinical research, more precise comparisons demand improved quantitation and greater precision. Preoperative and intraoperative assessment of peritoneal surface malignancy will improve patient selection. Now more than ever, postoperative distribution and volume assessments using noninvasive modalities are needed for follow-up.