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13 January 2019
By Nelya Melnitchouk, MD, MSc, Director, Program in Peritoneal Surface Malignancy, HIPEC, Gastrointestinal and General Surgery, Brigham and Women’s Hospital, Boston, Massachusetts, U.S., Instructor, Harvard Medical School
When patients with colorectal and appendiceal cancers develop metastatic disease to the peritoneum (the lining of the abdominal cavity), the treatment options are limited, and the survival rate is poor. Data suggest that up to 25 per cent of patients with colorectal cancer (CRC) can develop peritoneal disease.
Depending on the type of colorectal or appendiceal cancer, systemic chemotherapy is usually one of the treatment options. Another option, which can be offered to select patients, is cytoreductive surgery either with or without heated intraperitoneal chemotherapy (HIPEC). The goal of this treatment is to improve overall and disease-free survival without detracting from quality of life.
Cytoreductive surgery consists of removing all of the visible disease in the peritoneal cavity, and depending on the location of the disease, could include bowel resection, liver resection, or removal of other organs including the spleen or gallbladder. It is very important to achieve complete cytoreduction, leaving no disease behind. Completeness of cytoreduction is one of the main factors impacting the patient’s prognosis after surgery.
Once the resections are complete, and all of the disease visible to the eye is removed, HIPEC treatment is performed using a chemotherapeutic agent that has been heated to 42 degree C, which is infused into the abdomen via catheters. The solution is constantly circulated around the abdominal cavity to ensure all surfaces are exposed for 90 minutes. Both the chemotherapy agent and heat are cytotoxic to any cells that might have been left behind.
There are multiple factors that predict whether cytoreductive surgery could be beneficial. The main factor is the disease histology/behaviour. Patients with aggressive tumours that display poor differentiation and/or signet cells are less likely to benefit. For those patients who do undergo surgery, as previously stated, completeness of cytoreduction is key and can be judged by the completeness of cytoreduction score. Patients with no or minimal visible disease left behind (score of 0 or 1) have improved survival.
Frequently, laparoscopic exploration is done before the cytoreduction to assess for resectability. This allows assessment using the peritoneal carcinomatosis index (PCI), which is calculated based on the size and distribution of the tumours in the abdominal cavity. A high PCI score carries a worse prognosis and predicts lower likelihood of complete cytoreduction.
When determining which patients are candidates for this surgery, the patient’s performance status should not be underestimated. It has been shown again and again that patients with an Eastern Cooperative Oncology Group (ECOG) performance status under 2 have improved survival after cytoreduction/ HIPEC. Preoperative nutrition status is of paramount importance as well, as it correlates to postoperative complications. If the patient is malnourished before the surgery, total parenteral nutrition preoperatively can improve this.
Multidisciplinary tumour board discussions and recommendations are also extremely important when managing patients with peritoneal metastasis. Review by an expert pathologist is needed to confirm the histology both in appendiceal and colorectal cancer. The disease is often very heterogeneous with no standard algorithms for care. Shared decision-making should be emphasised, and careful counselling of the patient is needed.
At the Program in Peritoneal Malignancy at Brigham and Women’s Hospital, every patient is reviewed by a dedicated, multidisciplinary tumour board and the underlying pathology is reviewed by an expert gastrointestinal pathologist. Like many high-volume treatment centres that carry better outcomes, the BWH Program in Peritoneal Malignancy utilises enhanced recovery pathways to minimise the risk of post-surgical complications, improving both survival and quality of life for patients who undergo HIPEC, which is bringing many patients hope for a better prognosis.