Peritoneal carcinomatosis staging: how do I do it?

Peritoneal carcinomatosis is a frequent disease. Up to 75% of cases appear in the initial diagnosis of ovarian cancer, 15% are synchronous with colorectal cancer, and it is often metachronous in selected cases such as perforated or T4 tumours. The most important prognostic factor for these patients is the completeness of the surgical cytoreduction. The residual tumoral disease after cytoreduction can be classified according to the CC Score, and the probability of a complete cytoreduction is directly proportional to the extent of the peritoneal carcinomatosis.

Therefore, the extent of the disease is one of the most significant prognostic factors, and careful patient selection must be perform to avoid a huge surgery on patients with no or few options to improve. The two tools most widely used to calculate the extent of carcinomatosis are currently the CT-Scan and surgical exploration.

CT-scan not only assesses the volume and distribution of the disease but contributes to patient selection by calculating the extent of carcinomatosis and the response to neoadjuvant therapy, if it has been given. There are several aspects that should always be included: the description of the carcinomatosis, its distribution, the volume and type of ascites, and the radiological PCI. It is important to evaluate the presence of high-risk imaging featuresthat may limit the performance of a complete cytoreduction, such as a massive involvement of the porta hepatis or the small bowel or its mesentery. Recently, a radiology group published a new method to report all the key imaging features that will determine the feasibility of cytoreductive surgery and HIPEC. This is defined as the PAUSE criteria, which include Primary tumor and PCI, Ascites and Abdominal wall involvement, Unfavorable site of involvement, Small bowel and Mesenteric involvement, and Extraperitoneal disease. This is one of the last methods to try to standardize> the radiological report and therefore seek the optimal outcomes.

However, despite increased training, imaging cannot always detect the completeness of the disease. For example, miliary carcinomatosis in the small bowel is a contraindication for surgery, but it is very difficult to diagnose by CT-scan. This is why the role of surgical exploration is still important. In a patient treated with cytoreductive surgery, the first step of the operation should be to perform a proper assessment after laparotomy. With with the current development of minimally invasive diseases, exploratory laparoscopy has also a role.

In this talk we will focus on the role of imaging and surgical modalities in staging patients with peritoneal carcinomatosis.