Predicting Response of Head and Neck Cancer to Accelerated Radiation Therapy
According to a study published in the Journal of Clinical Oncology, patients with head and neck cancers are more likely to benefit from accelerated radiation therapy if a high proportion of their cancer cells have receptors for epidermal growth factor, a growth factor that plays a role in cell proliferation and survival.
Approximately 40,000 people in the United States are diagnosed with head and neck cancer every year. Cancers of the head and neck include cancers of the nasal cavity and sinuses, mouth, and throat. According to the American Cancer Society, 11,000 people died from head and neck cancer in 2004. Standard treatment for head and neck cancer is largely determined by the stage (extent to which the cancer has spread) and by the specific locations within the head or neck area where the cancer has spread.
Among head and neck cancer patients receiving radiation therapy, one reason for treatment failure is the accelerated regrowth of cancer cells that can occur during fractionated radiation therapy (radiation therapy that is split into smaller doses and administered over the course of several days). To overcome this problem, researchers have investigated accelerated radiation therapy schedules. According to these schedules, higher daily doses of radiation are given over fewer days. Some patients may be more likely than others to benefit from these accelerated schedules. One factor that may influence patient response to different radiation therapy approaches is the presence of epidermal growth factor receptors (EGFR) on cancer cells. Epidermal growth factor plays a role in cell proliferation and survival, and cancer cells are more likely than normal cells to have receptors for this growth factor.
In order to determine whether patients with higher levels of EGFR are more likely to benefit from accelerated radiation schedules than patients with lower levels of EGFR, an international group of researchers assessed 304 head and neck cancer patients. They had participated in a randomized clinical trial of accelerated versus conventional radiation therapy. Among patients with lower levels of EGFR, there was no benefit of accelerated radiation therapy compared to conventional radiation therapy. Among patients with higher levels of EGFR, however, those who received accelerated radiation therapy were less likely to have persistent or progressing cancer than those who received conventional radiation therapy.
The researchers conclude that EGFR expression on cancer cells influences response to radiation therapy. Head and neck cancer patients with high EGFR levels appear to benefit from accelerated radiation therapy. Recent research has also evaluated the combination of radiation therapy with the EGFR-blocking drug Erbitux® (cetuximab) among patients with advanced head and neck cancer. These results are promising.
Reference: Søren MB, Atasoy BM, Daley FM et al. Epidermal growth factor receptor expression in pretreatment biopsies from head and neck squamous cell carcinoma as a predictive factor for a benefit from accelerated radiation therapy in a randomized controlled trial. Journal of Clinical Oncology. 2005;23:5560-5567.
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