Some patients with head and neck cancer can be safely spared the risk and expense of surgery by undergoing a CT scan to predict whether the disease is in check after radiation therapy, according to study findings University of Florida doctors released today (Oct. 18) at the annual meeting of the American Society for Therapeutic Radiology and Oncology.
Researchers with the UF Shands Cancer Center have identified criteria doctors can use to evaluate CT scans four weeks after patients undergo initial treatment. If these criteria are met, there is a 94 percent likelihood a patient's lymph nodes are cancer free, said Stanley L. Liauw, M.D., a resident in radiation oncology. Using a CT scan was found to be much more accurate than relying on a physical exam to assess response to treatment.
Radiation therapy is commonly used to treat the more than 40,000 U.S. patients a year who develop advanced head and neck cancer. After radiation therapy, doctors often operate to remove affected lymph nodes. But UF physicians say in some cases surgery is unnecessary, and can increase recovery time, lead to infection and possibly compromise a patient's quality of life.
The current study builds on previous research involving 95 head and neck cancer patients. In two-thirds of the patients who underwent surgery after radiotherapy, the removed lymph nodes turned out to be cancer free, noted UF radiologist Anthony Mancuso, M.D. Mancuso collaborated with UF radiation oncologists Robert Amdur, M.D., Christopher Morris, M.S., and William Mendenhall, M.D.
By comparing nodes visualized on a CT scan with the same nodes after they were removed, the researchers developed criteria doctors could use to examine nodes using a non-invasive CT scan to identify whether the disease was knocked out. Nodes deemed to be clear of cancer were 1.5 centimeters or smaller and had borders that were sharply defined on the CT scan, rather than fuzzy.
In the current study, UF researchers examined the medical records of 549 patients who were treated with radiotherapy at UF for advanced head and neck cancer between 1990 and 2002; 341 patients later underwent surgery to remove lymph nodes. UF doctors, basing their treatment on the results of the previous research, did not remove lymph nodes in patients who met the CT scan criteria. Results confirmed that a CT scan could be used to reliably predict whether the lymph nodes would be negative for cancer.
A simpler method of CT interpretation (using lymph node size and the presence of an abnormal appearance within the lymph node) predicted, with a 94 percent accuracy, when a patient was cancer free. In 33 patients who were spared neck dissection on the basis of their post-treatment CT scan, only one suffered a recurrence of the disease in the lymph nodes. That patient was then scheduled for surgery, and the involved nodes were successfully removed. The patient recovered.
A newer imaging technology, the PET scan, cannot give an accurate reading of the nodes until two to three months after radiation therapy, making it impossible to surgically intervene in a timely manner, said Mancuso, a co-investigator.
"There is no other alternative method that is effective within the six-week decision-making window," Mancuso said.
Suresh Mukherji, M.D., chief of neuroradiology at the University of Michigan, said the data was promising and could lead to improvements in patient treatment.
"So far this is a single institute study. We need to have multiple institutes adopt this and see if results are similar over the long term," Mukherji said.
Liauw said, "I think it would be great if doctors could look at this data and feel comfortable with just doing a CT scan after radiation in order to know if a neck dissection is necessary. If this data is understood and accepted, we could limit the risk of side effects for several patients. Now it is important to focus more and more on reducing complications and improving quality of life as our treatments are getting better."