Chapter 122: Cytoreductive Surgery and Peritoneal-Based Therapies

INTRODUCTION

Peritoneal metastases occur by “seeding” or direct contact unlike the more common hematogenous or lymphatic routes seen in most malignancies. This method of spread leads to considerable challenges in the management of patients due to difficulty in detection and quantification (staging) of burden of disease as there may be no identifiable mass formation on imaging studies. In addition, they can pose technical difficulties in the surgical extirpation of disease given that abdominal viscera are covered by a layer of visceral peritoneum which can be studded with disease. This leads to considerable discomfort and impairment of quality of life of patients via pain, ascites, cachexia, and malignant bowel obstruction, which ultimately leads to inanition and death. The application of cytoreductive surgery (CRS) and intraperitoneal therapies to this disease process offers an attractive method of tumor reduction and drug delivery that could overcome the drawbacks of delivery of intravenous therapy including tumor hypoxia and ischemia, and drug resistance leading to attrition of systemic dosing.¹

EPIDEMIOLOGY AND DIAGNOSIS

Peritoneal disease comprises a heterogeneous group of malignancies with a common phenotypic expression of metastatic sites. Predominantly, there are two types of peritoneal disease: primary and secondary. Diseases arising from the peritoneum such as mesothelioma, desmoplastic round cell tumors, and primary peritoneal disease are rare. The majority of the tumors that present to the surgical oncologist are composed of secondary tumors, with an estimated incidence of 8% to 10% of all colorectal carcinomas, 30% of gastric carcinomas, and 60% to 70% of all ovarian carcinomas developing peritoneal disease (Table 122-1).^2-4

The gold standard for detection of peritoneal disease is pathological examination after visual suspicion during laparoscopy or laparotomy. Conventional imaging techniques for detection of peritoneal disease have poor discrimination of disease from normal peritoneum. This is due to either small size of tumor deposits or a sheet-like disease, which is difficult to detect on conventional optical interpretation of images. Improvements in imaging techniques including multi-slice CT scan and MRI have led to increased sensitivity of detection of peritoneal disease. The application of diffusion weighting to regular MRI techniques has been suggested to increase the sensitivity to 95% in patients with a high probability of disease.⁵ The application of PET imaging for detection of peritoneal disease ...