Proton therapy may reduce serious side effect of lung cancer treatment

Patients with locally advanced lung cancer who receive chemotherapy and proton therapy, a specialized form a radiation therapy only available in a few centers in the United States, have fewer instances of a serious side effect called bone marrow toxicity than patients who receive chemotherapy and another type of radiation therapy called intensity modulated radiation therapy (IMRT), according to a study presented at the 2008 Chicago Multidisciplinary Symposium in Thoracic Oncology, sponsored by ASTRO, ASCO, IASLC and the University of Chicago.

The standard of care for patients with locally advanced non-small-cell lung cancer is chemotherapy and radiation therapy. Unfortunately, these aggressive treatments can put patients at risk of a serious side effect called bone marrow toxicity that can lead to delayed or missed treatments, hospitalizations and growth problems.

To try to alleviate this side effect, doctors at M.D. Anderson Cancer Center examined 142 patients with locally advanced non-small cell lung cancer. Of those, 75 patients received chemotherapy plus a type of targeted photon (X-ray) radiation therapy called intensity modulated radiation therapy (IMRT). The remaining 67 patients received chemotherapy and proton beam therapy. Proton beam therapy is a type of external beam therapy that uses protons rather than photons to kill fast growing cancer cells.

"Because proton therapy allows us to control the radiation differently than other types of external beam radiation therapy, we were hopeful that we could keep radiation away from critical structures, like the bones to avoid bone marrow toxicity," said Ritsuko Komaki, M.D., FASTRO, a radiation oncologist at M.D. Anderson Cancer Center in Houston.

After a follow-up time of 17 months, researchers found patients who received proton therapy with chemotherapy had a significant reduction in bone marrow toxicity compared to patients who received IMRT and chemotherapy. These findings suggest that using proton therapy over other types of radiation may allow doctors to give a higher dose of radiation without compromising the chemotherapy schedule to the lung tumor while avoiding some debilitating side effects, like bone marrow toxicity.

"These results are very promising for people with locally advanced lung cancer," said Dr. Komaki. "However, we need to now confirm these findings with a randomized trial."