Proton beam therapy outperforms IMRT in reducing bone marrow toxicity

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Patients treated for locally advanced non-small cell lung cancer who receive chemotherapy and proton beam therapy have fewer instances of bone marrow toxicity than patients who receive the standard treatment of intensity-modulated radiation (IMRT) and concurrent chemotherapy, according to findings reported Nov. 13 at the Chicago Multidisciplinary Symposium in Thoracic Oncology.

The researchers said that this is the first study to examine the benefits of proton beam therapy and concurrent chemotherapy in advanced lung cancer patients.

The occurrence of bone marrow toxicity—the reduction of hemoglobin, neutrophils, lymphocytes and white blood cells—results in a patient's inability to withstand aggressive treatment, rendering it less effective. The condition often leads to infection, bleeding, fatigue and even death, according to the investigators.

Researchers compared bone marrow toxicity levels in 142 patients treated for lung cancer between January 2003 and June of this year. All of the patients received chemotherapy; IMRT was administered to 75, while 67 were treated with proton beam therapy.

After 17 months, they found that the patients treated with concurrent chemotherapy and proton beam therapy experienced significantly less reduction in hemoglobin (zero vs. 4 percent), neutrophils (4 vs. 17 percent) and lymphocytes (54 vs. 87 percent) when compared to those treated with CT and IMRT. The differences remained when the gross tumor volume was considered.

“Standard care currently provides a 25 percent five-year survival rate. With proton therapy, we may now have an option that lessens this toxicity so that treatment dosage can be maximized,” said the study’s lead author Ritsuko Komaki, MD, from M.D. Anderson Cancer Center’s division of radiation oncology.

“Proton therapy may promise safer and more effective treatment for children, whose bone marrow is still developing, and elderly patients who are more prone to complications and cannot withstand aggressive treatment,” said the study’s senior author James Cox, MD, head of the division of radiation oncology.

M.D. Anderson in Houston is currently working with Massachusetts General Hospital in Boston to enroll patients in an NCI-approved randomized prospective clinical trial to confirm the initial findings.