Among the most promising treatments for peritoneal mesothelioma is a combination of cytoreductive surgery (CRS) and heated chemotherapy called hyperthermic intraperitoneal chemotherapy (HIPEC).
A study published February 2018 in the International Journal of Hyperthermia supports the value of this combination therapy for treating this asbestos-related cancer.
Researchers in the U.K. analyzed 9.5 years of data on 76 peritoneal mesothelioma patients who were treated with CRS and HIPEC.
“The results in this series suggest that CRS and HIPEC, even when complete cytoreduction is not achieved, is of benefit to patients with either low-grade or malignant mesothelioma and at present is the only treatment which has the potential for cure,” the authors wrote.
Using Two Mesothelioma Treatments Together
Peritoneal mesothelioma is a form of cancer that develops in the peritoneum, the tissue lining of the abdomen. It accounts for less than 20 percent of all cases of mesothelioma.
Many of the treatment options for peritoneal mesothelioma are similar to those of other asbestos-related cancers.
For many patients, however, the most promising treatment is a combination of:
Cytoreductive Surgery: CRS is a type of debulking surgery. Debulking removes as much of the tumor as possible. When tumor debulking is performed with curative intent and allows for complete removal of all visible cancer, it is called cytoreductive surgery.
Hyperthermic Intraperitoneal Chemotherapy: HIPEC places concentrated, heated chemotherapy into the abdomen during surgery. It delivers chemotherapy directly to cancer cells in this area.
Two Categories of Peritoneal Mesothelioma
Peritoneal mesothelioma often is categorized into two groups. Less aggressive tumors with a better prognosis are called low-grade peritoneal mesothelioma.
This category includes the cell types multicystic mesothelioma and well-differentiated papillary mesothelioma.
The other type of this cancer is diffuse malignant peritoneal mesothelioma. These tumors tend to be more aggressive and include epithelioid, biphasic and sarcomatoid subtypes.
Surgery Plus HIPEC Is a Powerful Combination
The U.K. researchers found using these two treatments together was particularly effective for low-grade disease.
“After complete cytoreduction, 100 percent overall survival was observed amongst patients with low-grade disease,” the authors wrote.
The authors also noted in their publication that although the therapies may not cure more aggressive peritoneal mesothelioma cancers, combining surgery and HIPEC can be the most effective treatment in these situations, too.
Treatment and Outcomes
Patients in the study ranged in age from 21 to 73, and 45 percent of them were female. Approximately half of the patients had low-grade disease and half had diffuse malignant peritoneal mesothelioma.
Sixty-eight percent of patients had cytoreduction surgery — complete tumor removal — and another 26 percent had maximal tumor debulking. This means surgeons removed nearly all, but not 100 percent of the visible tumor.
The remaining four patients had biopsies only. A small piece of their tumors was removed in order to make a diagnosis.
HIPEC was part of treatment for 88 percent of patients (67 people). All of the patients with low-grade disease were still alive by the end of the study period.
Even when considering low-grade and more aggressive disease together, the average disease-free survival was 58.8 months, or nearly five years.
Disease-free survival refers to the period of time before detectable disease returns after treatment is completed.
Average overall survival, which includes people living with disease after it recurs, was 97.8 months, or more than eight years.
Marker for Prognosis, Guidance for Treatment Choices
The study also measured the tumors for a marker called Ki-67 proliferation index. This test is performed in a lab on the cancer cells removed during surgery and gives mesothelioma doctors an understanding of how aggressive each person’s cancer is likely to be.
Study authors found a higher Ki-67 proliferation index was associated with worse survival after CRS for diffuse malignant peritoneal mesothelioma.
This information is useful for anyone newly diagnosed with peritoneal mesothelioma.
If a person has a tumor with a higher likelihood of recurring after treatment, their doctor may recommend more frequent, post-treatment follow ups.
The sooner a person knows their tumor may have returned, the more effectively it can be managed going forward.
This study contributes to a better understanding of how CRS and HIPEC work and who is likely to receive the best benefit from this combination treatment.
For patients with the most aggressive peritoneal mesothelioma cancers, additional options — such as immunotherapy or ongoing, post-surgical delivery of chemotherapy into the peritoneal cavity — may be additional treatments to consider.