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The study suggests that a PET imaging study before the start of treatment may predict the aggressivess of a cancer.

Pretreatment PET imaging helped predict survival in patients with head and neck squamous cell carcinoma treated with intensity-modulated radiation therapy, a retrospective analysis of data from a clinical series showed.

Uptake of FDG tracer in the primary tumor had a significant association with disease-specific survival and a strong trend with overall survival. Nodal uptake of FDG had a significant association with distant disease-free survival.

The findings suggest pretreatment PET imaging could lead to personalized therapeutic strategies for some patients with head and neck cancer, Min Yao, MD, PhD, said here at the Multidisciplinary Head and Neck Cancer Symposium.

"The standardized uptake value (SUV) in lymph nodes may serve as an imaging biomarker for selecting patients for more aggressive systemic chemotherapy," said Yao, of University Hospitals Case Medical Center in Cleveland.

"Since we now know that SUV of the lymph nodes is associated with distant metastasis, those patients with high SUV in lymph nodes may need more aggressive systemic chemotherapy," he added.

Several studies have linked higher SUV with worse outcomes in head and neck cancer. However, most of the studies involved small series of patients treated with conventional radiation therapy. Moreover, previous studies had not examined SUV of the primary tumor and lymph nodes separately.

"The purpose of our study was to determine the prognostic significance of maximal standardized uptake value [SUVmax] measured from FDG PET obtained before treatment for head and neck squamous cell carcinoma patients treated with intensity-modulated radiation therapy [IMRT]," Yao said.

Investigators reviewed data on 177 patients who had FDG PET imaging before undergoing IMRT for various types of head and neck cancer. The most common sites were oropharynx (87 patients), oral cavity (32), and larynx (32). Three-fourths of the patients had stage IV disease.

Yao said 125 patients received definitive IMRT, and the remaining 52 had postoperative treatment. Median follow-up was 22.6 months, 29.1 months among survivors. Overall survival was 75% at two years and 67.4% at three years. Distant disease-free survival was 83.4% and 78.8% at two and three years, respectively, and disease-specific survival was 84.8% and 78.8% at the same intervals.

The median SUVmax of lymph nodes was 10.8 in patients who developed metastases versus 7 in those who remained metastasis free (P=0.0124). Using an SUVmax cutoff of 11.3, investigators found that patients with lower values had a three-year survival of 82.1% compared with 63.4% in patients who had higher values (P=0.018).

In a multivariate analysis, the pretreatment SUVmax in the primary tumor was significantly associated with disease-specific survival (P=0.045) and fell just short of statistical significance for overall survival (P=0.051). SUVmax of the lymph nodes predicted distant disease-free survival (P=0.034).

The combination of an SUVmax 13 in lymph nodes and stage T4 disease predicted distant metastasis with a sensitivity of 80% and specificity of 64%.

"This is likely to make a real difference in the care of the patient," said Graham, of the University of Iowa in Iowa City.

PET imaging previously demonstrated value in cancer staging, and the findings by Yao and colleagues suggest PET also can show the metabolic activity level of a tumor, a finding that has implications for treatment, Michael Graham, MD, PhD, said at a media briefing.

Source: MHNCS

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