Proton Therapy and Concurrent Chemotherapy May Reduce Bone Marrow Toxicity in Advanced Lung Cancer

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 do.

The researchers, from the University of Texas M.D. Anderson Cancer Center (Houston, TX, USA), presented their findings November 2008 at the 2008 Chicago Multidisciplinary Symposium in Thoracic Oncology (IL, USA). It is the first study to examine the benefits of proton beam therapy and concurrent chemotherapy in advanced lung cancer patients.

The conventional treatment for locally advanced non-small cell lung cancer is intensity-modulated radiation with concurrent chemotherapy. Most lung cancer patients who receive this therapy are at risk of bone marrow toxicity, a debilitating side effect of treatment that additionally weakens a patient's already vulnerable immune system. The occurrence of bone marrow toxicity--the reduction of hemoglobin, lymphocytes, neutrophils, and white blood cells--results in a patient's inability to withstand aggressive treatment, making it less effective. This condition often leads to infection, bleeding, fatigue, and even death.

Researchers compared bone marrow toxicity levels in 142 patients treated for lung cancer between January 2003 and June 2008. All of the patients received chemotherapy; IMRT was administered to 75, while 67 were treated with proton beam therapy. After 17 months, patients treated with concurrent chemotherapy and proton beam therapy experienced significantly less reduction in hemoglobin (0% vs. 4%), neutrophils (4% vs. 17%), and lymphocytes (54% vs. 87%) when compared to those treated with computed tomography (CT) and IMRT. These differences remained when the gross tumor volume was considered.

"Our goal is to find the best way to treat the cancer without further weakening the patient,” said Ritsuko Komaki, M.D., professor in M.D. Anderson's division of radiation oncology and lead author on the study. "Standard care currently provides a 25% five-year survival rate. But as a physician, I have seen how treatment affects patients' overall health: they are tired, suffer from night sweats, are prone to infection and have to compromise their treatment. With proton therapy, we may now have an option that lessens this toxicity so that treatment dosage can be maximized.”

Proton beam therapy ionizes cancer cells by stripping away electrons, consequently mutating the cells' DNA so that they cannot divide and proliferate. Protons are significantly heavier than X-rays, allowing them to travel in a straight path through the body without being deflected. While radiation therapy destroys both the tumor and the healthy tissue surrounding it, proton therapy can target a tumor precisely with little damage to normal tissue.

"This study suggests that proton beam therapy may benefit patients who are extremely vulnerable to bone marrow toxicity,” said James Cox, M.D., professor and head of the division of radiation oncology and the study's senior author. "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.”

M. D. Anderson is currently working with Massachusetts General Hospital (Boston, MA, USA) to enroll patients in a U.S. National Cancer Institute- (NCI; Bethesda, MD, USA)-approved randomized prospective clinical trial to validate these initial findings.

At the conference, Dr. Cox also presented his study on proton beam therapy and its effects on tissue toxicity.

Related Links:
University of Texas M.D. Anderson Cancer Center