A new radiation treatment technique that targets head and neck tumors without completely destroying the salivary glands saves patients long-term discomfort and enables them to function more normally, a study from Washington University School of Medicine in St. Louis has shown. Using this sophisticated technique, researchers sculpted radiation beams so they could attack tumors in the neck while sparing lobes of the parotid salivary glands‹the glands below the ear. At intervals after therapy, they assessed saliva flow and quality of life.
"This is the pioneer study to directly show that the more salivary function physicians can preserve, the higher patients' quality of life will be," says Clifford K.S. Chao, M.D., assistant professor of radiology. Chao will report the results Oct. 24 at the annual meeting of the American Society for Therapeutic Radiology and Oncology in Boston.
Patients who receive radiation therapy for head and neck cancers often are troubled by xerostomia, or dry mouth. They constantly feel parched and have to drink frequently, even during the night. And they cannot speak normally or eat solid food. Their sense of taste also is affected.
The researchers assessed 41 patients whose head and neck tumors had been treated by intensity-modulated radiation therapy (IMRT) between 1997 and 1999. This new technique can construct a 3-D representation of the neck from CT scans and feed the image into high-performance computers. The computers then sculpt the radiation beam to deliver maximum power to the tumor while avoiding normal tissues. Six weeks, three months and six months after therapy, the researchers compared saliva flow to that measured before treatment. They also gave the patients a questionnaire about quality of life.
The objective and subjective tests correlated directly. More saliva flow meant greater comfort and ease in speaking and eating. Calculations by Chao and colleagues revealed how saliva flow declined exponentially with higher radiation dose. This information should enable physicians and patients to make more informed treatment decisions.
In a separate study, the researchers assessed 24 patients with tumors in the oropharynx‹the back of the mouth. All the patients were treated with IMRT, but 12 also received surgery, and nine received IMRT plus chemotherapy. Ninety percent of the tumors were controlled after two years follow-up and only one-fourth of the patients experienced dry mouth. In contrast, three-fourths of patients treated by conventional radiation therapies complain of dry mouth. Another study involved 125 patients with tumors of the nasopharynx, or nasal passages. Sixty-one percent of 103 who received only conventional radiation therapy had their tumors controlled, and 73 percent reported dry mouth. All 13 patients who received conventional radiation therapy plus chemotherapy had their tumors controlled, but 75 percent reported dry mouth. In contrast, all nine patients who received IMRT plus chemotherapy had their tumors controlled, and 22 percent reported dry mouth.
"IMRT is the cancer treatment of the future," Chao says. "It's still in the very early stages, but these studies show that it can kill tumors while sparing normal tissues and preserving salivary function."
Chao C, Deasy JO, Markman J, Haynie J, Perez CA, Purdy JA, Low DA. Functional outcome of parotid gland sparing in patients with head and neck cancers receiving intensity-modulated (IMRT) or 3-D radiation therapy. Oral presentation at American Society for Therapeutic Radiology and Oncology annual meeting, Boston, Oct. 22-26, 2000.
The research was supported by grants from the National Institutes of Health and NOMOS Corp.
Huang C, Chao C, Perez CA, Low DA. Tumor response and salivary function sparing in patients with oropharyngeal squamous cell carcinoma treated with intensity modulated radiation therapy (IMRT) with/without chemotherapy: the Mallinckrodt Institute of Radiology results. Oral presentation at American Society for Therapeutic Radiology and Oncology annual meeting, Boston, Oct. 22-26, 2000.
Cengiz M, Chao C, Perez CA. Intensity-Modulated Radiotherapy (IMRT) with concurrent cisplatin chemotherapy (CT) yields superior therapeutic outcome than conventional techniques with or without chemotherapy in locally advanced nasopharyngeal carcinoma. Poster at American Society for Therapeutic Radiology and Oncology annual meeting, Boston, Oct. 22-26, 2000.
The full-time and volunteer faculty of Washington University School of Medicine are the physicians and surgeons of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC Health System.