Rare Mesothelioma Subtype Less Likely to Respond to Treatment

A new meta-analysis confirms that people with the sarcomatoid type of mesothelioma are less likely to respond to systemic chemotherapy than are people with other histological subtypes.

Citing a lack of research on the responsiveness of different types of mesothelioma, scientists with the Mayo Clinic in Minnesota and the Levine Cancer Institute in Charlotte, NC reviewed the medical literature for any studies that broke down responses by histological subtype. Of the 544 studies analyzed, 30 included sarcomatoid mesothelioma patients and met the trial criteria that patients be treated only with chemotherapy.

The selected studies included a total of 1,475 mesothelioma patients. Sixty-eight percent of patients (1,011) had the epithelioid variety of mesothelioma, the most common type. Just over 13 percent (203) had biphasic tumors and 9.3 percent (137) were diagnosed with the least common and most lethal type of mesothelioma – sarcomatoid.

All the study subjects were treated with first or second-line systemic chemotherapy but their response patterns were very different. Overall, 21.9 percent of the mesothelioma patients studied had either a partial or complete response to chemotherapy, meaning that the treatment had some measureable impact on the size of their tumors.

But for patient with the sarcomatoid subtype of mesothelioma, the response rate was significantly lower. Only 5.9 percent of the chemotherapy-responsive mesothelioma patients were those with sarcomatoid tumors. These 19 sarcomatoid mesothelioma patients accounted for a 13.9 percent chemotherapy response – an 8 percent lower response rate than the overall mesothelioma rate.

“Partial and complete responses to systemic therapies appear to be less common among patients with sarcomatoid tumors,” concludes Mayo Clinic oncologist Dr. Aaron Mansfield, lead author on the newly-published study.

The study focused on mesothelioma clinical trials published between January 2000 and March 2014. Although mesothelioma is frequently treated with multiple types of therapies, including chemotherapy, radiotherapy and/or surgery, this study was limited to patients who only underwent chemotherapy.

Source:

Mansfield, AS, et al, “Systematic review of response rates o sarcomatoid malignant pleural mesotheliomas in clinical trials”, September 1, 2014, Lung Cancer, Epub ahead of print