Boosting the blood count – in effect, curing anemia – in conjunction with radiation therapy won't help patients with head and neck cancer fare any better than with radiation alone, says a national study led by Jefferson Medical College researchers.
Physicians have known for decades that patients who have anemia and are undergoing radiation therapy, especially for head and neck cancer, do much worse in terms of controlling their cancer and survival.
One theory proposes that anemia makes tumors more resistant to radiation because it promotes hypoxia, or a lack of oxygen, within the tumor, says Mitchell Machtay, M.D., Walter J. Curran Jr., M.D., associate professor and vice chair of radiation oncology at Jefferson Medical College of Thomas Jefferson University in Philadelphia and at Jefferson's Kimmel Cancer Center. Hypoxia is known to cause such resistance.
"The hope was that by correcting anemia, there would be a better oxygenation of the tumor environment and the tumor would be more sensitive to radiation and easier to kill," he says. To find out, he and his co-workers looked at 141 patients with head and neck cancer who had mild to moderate anemia. Of those, 71 patients were randomly assigned to receive the hormone erythropoietin during radiation therapy, while 70 were given only radiation. Erythropoietin spurs production of oxygen-carrying red blood cells.
Yet, while erythropoietin significantly increased the red blood cell count and lessened the patients' anemia, it didn't help them have better tumor control or survival.
Dr. Machtay presents his group's findings Oct. 5, 2004 at the American Society for Therapeutic Radiology and Oncology's 46th annual meeting in Atlanta.
Patients had squamous cell carcinoma, which can include cancers of the voicebox, throat, and mouth, and is primarily a smoking-caused cancer.
"We've clearly shown that just correcting the anemia is probably not going to help the patients," Dr. Machtay says. "Anemia is probably not the cause of the poor prognosis, but rather a marker for such a prognosis. You just can't correct it and think that will change the tumor control outcome."
He points out that a similar study published last year in the journal The Lancet in fact showed that those who were given erythropoietin and radiation actually did worse than those patients treated with radiation alone.
He argues for more basic research on the problem.
"There's a need to go back to pre-clinical laboratory studies and investigate how in cases of anemia and tumor hypoxia, erythropoietin and other growth factors could affect outcome at a biological level," he says. The study was conducted by the Radiation Therapy Oncology Group, a federally funded cancer clinical trials group that carries out multi-disciplinary research nationwide. Dr. Machtay is the group's deputy chairman.