New Study Points to Benefits of IMRT for Mesothelioma Treatment

There is more evidence that mesothelioma patients who have lung sparing surgery can live longer if it’s followed up with highly targeted radiation therapy.

In the first study to come out of Israel on the subject, a team of oncologists, pulmonologists, radiation oncologists, and thoracic surgeons at Rabin Medicine Center in Petah Tikva say intensity modulated radiation therapy (IMRT) is safe and effective for slowing down the growth of pleural mesothelioma tumors.

The Challenge of Radiotherapy for Mesothelioma

The irregularity of malignant mesothelioma tumors makes them difficult to treat with standard external beam radiotherapy without damaging healthy tissue and causing serious side effects.

This is particularly problematic in patients who still have both lungs, either because they were not good candidates for surgery or because they elected to have lung-sparing P/D surgery.

But IMRT is changing the outlook for these mesothelioma patients. IMRT is a type of radiotherapy that allows clinicians to carefully conform the dose to the size and shape of the targeted tumor, minimizing the amount of radiation absorbed by healthy cells and cutting the risk for complications.

As experience with IMRT has improved, centers around the world have reported better results in treating patients with malignant mesothelioma, one of the most treatment-resistant cancers.

IMRT for Pleural Mesothelioma

For their IMRT study, the Israeli researchers identified 27 mesothelioma patients who had been treated with IMRT at their institution between 2007 and 2016.

Some patients had undergone radical EPP surgery and had only one lung while others were not eligible for surgery. (Rabin Medical Center does not yet offer the more conservative lung-sparing P/D surgery.)

Most of the patients were men and most had the most common subtype of mesothelioma, which is epithelioid.

All patients studied received 54 Gy of radiation in 2 Gy fractions. About a quarter of them — especially those that had not undergone surgery — also had systemic chemotherapy.

Targeted Radiation Stopped Mesothelioma Growth

Although pleural mesothelioma is usually fatal within 18 months, even with the gold standard treatment, the IMRT patients had a mean overall survival of nearly three years (34.9 months).

In many cases, it took more than a year-and-a-half for mesothelioma tumors to either come back in the place where the original tumor was (local recurrence) or to begin growing in a new spot (distant recurrence). The mean time it took for the disease to be said to be progressing again following IMRT was 26.7 months.

While the Israeli team acknowledges that their small sample size limited their study somewhat (mesothelioma is, after all, a very rare cancer), they say their results provide further evidence that IMRT deserves to be studied more intensely as a potential treatment for people with pleural mesothelioma.

“We found the modern IMRT technique to be feasible and effective,” concludes the report in Thoracic Cancer. The low levels of toxicity and encouraging local control and survival rates suggest radiotherapy for localized malignant pleural mesothelioma is an important treatment option for patients.”

Source:

Simon, M, et al, “Intensity‐modulated radiotherapy is a safe and effective treatment for localized malignant pleural mesothelioma”, September 21, 2018, Thoracic Cancer