Peritoneal Carcinomatosis refers to the extensive spread of malignant tissue throughout the abdomen (the peritoneum). It is not an individual form of cancer, but is a term used to describe widespread abdominal metastases from other forms of the disease, such as peritoneal mesothelioma or colorectal cancer. Historically, peritoneal carcinomatosis has presented with a poor prognosis and a median survival of about three months, but advances in treatment modalities are offering hope that effective therapies are now available. Doctors from Sweden have recently described their use of peritonectomy and heated intra-peritoneal chemotherapy (HIPEC) to treat a number of patients with peritoneal carcinomatosis. Under certain conditions, their results are very promising.

Introduction to the Study

Peritonectomy refers to the surgical removal of malignant tissues in the peritoneum. There are a number of individual techniques that fall under the peritonectomy framework and the one chosen will be based on the patient’s disease and his or her overall health. Heated intra-peritoneal chemotherapy (HIPEC) is a method of chemotherapy where the chemo agent is heated to 107.6 degrees Fahrenheit (42 degrees Celsius) and then delivered to the abdomen. Heating the chemo agent has three important benefits over standard chemotherapy:

1. Cancer cells are more sensitive to heat than are regular cells and they die-off at 107.6(F)/42(C).
2. The heat increases the cytotoxic power of the chemo agent, making it more powerful and, hopefully, killing more cancerous cells.
3. The added heat softens the actual tumor nodules, which allows more of the chemo agent to be absorbed by the malignant tissues.
   (source: http://www.hipec.org/files/HIPEC.pdf)

When treating peritoneal carcinomatosis, HIPEC is delivered for 90 minutes immediately following the surgery. This allows the chemotherapy to have an immediate impact on the residual tumor cells.

Some earlier studies have shown that the combination of peritonectomy and HIPEC has a positive impact on patient survival time for people with peritoneal carcinomatosis. The Swedish doctors whose study we are discussing here collected data for 103 patients who underwent peritonectomy/HIPEC between 2003 and 2006. The individual cancers represented in the sample were: pseudomyxoma peritonei, colorectal cancer, gastric cancer, ovarian cancer and peritoneal mesothelioma. Only patients with strictly peritoneal disease were enrolled; patients with metastasis to areas outside the abdomen were excluded from the study. The actual chemotherapy agent was adjusted based on the type of cancer involved. The mesothelioma patients received cisplatin and doxorubicin.

Results

The results from the study show promise, but they are not without complication. The authors did not break out the survival rates for each of the individual cancers, but they did show that overall survival averaged 72.3% at 2 years, which is better than previous cohorts of patients with peritoneal carcinomatosis who underwent traditional therapy. The morbidity rate was 56.3%, which they state was high, but comparable to other studies that have investigated peritonectomy/HIPEC. Reasons offered for the high morbidity rate include surgical complications resulting from the interference of scar tissue from previous surgeries, as well as the relatively high doses of chemotherapy that the patients received. Neutropenia, which is condition characterized by an abnormally low number of the most common form of white blood cells (neutrophils), was a common side effect of HIPEC and the authors urge that patients who undergo HIPEC are tested for it. They also urge that patients be treated in isolation to help prevent against the development of an infection that the body will be compromised in fighting due to the lower white blood cell count.

Conclusion

The most important factors that led to a successful treatment with long-term benefits included patients with a strong performance status and those who achieved optimal cytoreduction, i.e., those whose surgery removed all visible tumor tissue. As regards the former condition, the authors concluded that good performance status was a good prognostic factor, but that age was not. They found that patients who were otherwise healthy, even if older, were just as likely to have a strong outcome as those patients with a good performance status who happened to be younger. Because of these findings, the authors recommend that simply using patient age as a weighing factor for this treatment should be avoided.

They felt that optimal cytoreduction was a key component to a successful outcome. Because chemo agents cannot penetrate tumors larger than 2mm, surgeons should attempt to remove all of the visible malignancy. If they cannot remove all of the visible tissue, the HIPEC may not be able to destroy all of the residual cells, which would lead to a return of the cancer. The authors state that in patients with sub-optimal cytoreduction, the use of the procedure is controversial because of the morbidity issues. But for candidates who are otherwise healthy and where optimal cytoreduction is achieved, peritonectomy and HIPEC may be an effective treatment for people with peritoneal carcinomatosis.

Labels: mesothelioma