PHOENIX – Thermal imaging was able to detect small and early changes in the temperature of mucosal surfaces – a possible predictor of the development of mucositis – among 34 patients who were treated with chemoradiotherapy for locally advanced squamous cell carcinoma of the head and neck.
"Detection of these early changes using sensitive thermal imaging technology would allow identification of patients who will require more intensive supportive care," said Dr. Ezra Cohen, who presented the pilot study at the head and neck cancer symposium sponsored by the American Society for Radiation Oncology.
Radiotherapy-associated mucositis manifests initially as erythematous areas in the treatment field, which are accompanied by an intense inflammatory response histologically. Thus, Dr. Cohen and his associates had hypothesized that patients destined to display severe mucocutaneous toxicity would demonstrate greater alterations in thermal intensity early in therapy, compared with identically treated counterparts who do not subsequently develop the toxicity.
The researchers further hypothesized that they could measure those changes with infrared thermal imaging, a noninvasive technique that allows visualization and quantification of changes in skin or mucosal surface temperature.
The 34 patients (28 male, mean age 58 years) in the pilot study were treated with identical chemoradiotherapy regimens of 5-fluorouracil and hydroxyurea with a median radiation dose of 74 Gy for cancers of the oral cavity or oropharynx.
Using a portable device developed at Argonne National Laboratory in Illinois, the investigators conducted noninvasive baseline and weekly thermal imaging. The device detects infrared light naturally emitted from the skin or mucosal surface and generates an electrical signal, which is amplified and converted into digital data flow that is visualized in color on a monitor.
Images courtesy Dr. Ezra Cohen
The images on top are sequential through treatment from left to right. The first shows the subject before treatment. The circled area is the region that is about to receive the full dose of radiotherapy. Red is hot and blue is cold. You can see that the circled area gets hotter as treatment progresses. The difference between the first and second images is what's correlating with mucositis. The images on the bottom show how the area of interest in the thermal image (far right) correlates with the radiation plan (left and center image). The area outlined green is the one receiving the highest radiation dose and contains the cancer.
Grade 3 mucositis based on the National Cancer Institute’s Common Terminology Criteria for Adverse Events v3.0 was observed in 53% of the patients, and dermatitis in 21%. All patients displayed an increase in temperature within the radiation field.
Investigators charted a statistically significant positive association between an early rise in temperature in oral mucous membranes when compared with a reference area and mucositis grade (P = .03). For every 1 C increase in temperature, compared with the reference (temperature near the medial angle of one eye), there was a 0.157 increase in average subsequent mucositis grade, reported Dr. Cohen, codirector of the head and neck cancer program at the University of Chicago.
Mucositis and its clinical sequelae are consistently reported as the most clinically significant acute toxicity in the treatment of locally advanced squamous cell carcinoma of the head and neck with chemoradiotherapy, according to Dr. Cohen, who also chaired the meeting. Patient to patient variability in mucositis is related to radiotherapy dosing, fractionation, and volumes, but there also appear to be individual differences in "normal tissue tolerance," even among patients on the same treatment regimen, he said.
"Larger studies with greater dynamic ranges in mucositis scoring are warranted to evaluate whether this tool can help predict which patients would be in need of early intervention to prevent acute complications," he said.
The study was funded by the National Institutes of Health and the University of Chicago Comprehensive Cancer Center. Dr. Cohen and his associates said they had no relevant financial disclosures.