MD Anderson researchers say too many patients who might benefit from IMRT for mesothelioma never complete the treatment. The problem could be impacting their survival.
Intensity Modulated Radiotherapy (IMRT) is a type of targeted radiation. It is designed to direct as much radiation as possible into the mesothelioma tumor without harming the surrounding tissue.
Patients who have a combination of surgery, chemotherapy, and IMRT for mesothelioma have the best odds of survival.
But at MD Anderson Cancer Center, only two thirds of eligible patients completed IMRT after mesothelioma surgery. The new study aimed to find out why.
Trimodal Therapy and Mesothelioma Survival
Malignant mesothelioma rarely responds to a single cancer therapy. Trimodal therapy combines several different treatments to maximize success.
A 2017 MD Anderson study found that trimodal therapy including IMRT for mesothelioma extended survival by nearly nine months. Epithelioid mesothelioma patients who had this treatment lived an average of 23.4 months.
Mesothelioma patients may have radiation for different reasons. Sometimes, it is used to shrink a tumor before surgery. Sometimes, radiation is used to relieve symptoms.
Radiation delivered after surgery is called adjuvant radiotherapy. The new study focuses only on adjuvant IMRT for mesothelioma.
Why Some Patients Do Not Complete IMRT for Mesothelioma
The newest MD Anderson study included 160 pleural mesothelioma patients diagnosed between 2004 and 2017. About 60 percent of them had extrapleural pneumonectomy. The other 40 percent had lung-sparing pleurectomy/decortication.
All of the patients were candidates for adjuvant IMRT for mesothelioma. But only 66 percent of them completed the treatment.
In 19 cases, this was because the patient died before they could start radiotherapy. For 21 patients, the radiation dose they needed caused too many side effects.
In the remaining patients, either surgery complications, delayed recovery, or an unknown reason kept them from completing IMRT for mesothelioma.
Patients with the most advanced disease going in and those with a history of smoking were less likely to complete IMRT.
Age and Surgery Type Have Little Impact on IMRT Success
Surprisingly, other factors – like age and surgery type – had little impact on the completion of IMRT for mesothelioma.
“Extrapleural pneumonectomy or pleurectomy/decortication, margin status, age, and histology, were not associated with receiving adjuvant intensity-modulated radiation therapy,” writes lead author David B. Nelson.
The question of IMRT completion is worth exploring, especially among patients with early-stage mesothelioma. Nelson and his team published another study on IMRT for mesothelioma earlier this year. That study used data from the National Cancer Database. It found that early-stage patients had the best results with trimodal treatment.
“Adjuvant radiation was associated with improved survival among those who were stage I-II (P=0.024), but not stage III or IV,” wrote Dr. Nelson. Patients in the later stages of mesothelioma lived for about the same amount of time as those who did not have any adjuvant radiotherapy.
Nelson, DB, et al, “Return to intended oncologic treatment after surgery for malignant pleural mesothelioma”, September 2019, Journal of Thoracic and Cardiovascular Surgery, Epub ahead of print, https://www.ncbi.nlm.nih.gov/pubmed/31430846
Nelson, DB, et al, “Defining the role of adjuvant radiotherapy for malignant pleural mesothelioma: a propensity-matched landmark analysis of the National Cancer Database”, April 2019, Journal of Thoracic Disease, pp. 1269-1278, http://jtd.amegroups.com/article/view/28310/20869