Source: www.oncologystat.com
Author: Staff

The metabolic activity of head and neck squamous cell carcinoma on pretreatment imaging independently predicts outcomes in patients who undergo intensity-modulated radiation therapy, new data show.

This imaging information can be used to tailor treatment, especially to reduce the risk of distant metastases, lead investigator Dr. Min Yao said at a head and neck cancer symposium sponsored by the American Society for Radiation Oncology.

Higher standardized uptake value (SUV) of the primary tumor and of the lymph nodes predicted worse outcomes in multivariate analyses presented by Dr. Yao, a radiation oncologist at the Case Western Reserve University, Cleveland.

“Several papers have shown that the standardized uptake value (SUV) is a prognostic factor in head and neck cancer,” Dr. Yao told attendees. Most of these studies were small series, involved patients receiving conventional radiation therapy, and did not evaluate SUV of the primary tumor and lymph nodes separately.

Dr. Yao and his colleagues analyzed outcomes in 177 patients treated for head and neck squamous cell carcinoma with intensity-modulated radiation therapy (IMRT) between 1999 and 2006.

The patients had a pretreatment positron emission tomography scan using fluorodeoxyglucose as the tracer (FDG-PET), and the maximal SUV was determined for both the primary tumor and the involved lymph nodes. The patients then underwent IMRT with curative intent.

Seventy-seven percent of the patients were male. Twenty-nine percent were receiving IMRT postoperatively, whereas the rest were receiving it as definitive therapy. The cancer was most commonly located in the oropharynx (49%) and was stage IV (76%), said Dr. Yao, who reported having no conflicts of interest related to the study.

The median duration of follow-up after the end of IMRT was 22.6 months among all patients and 29.1 months among living patients. The median time elapsed between the pretreatment scan and the start of IMRT was 28 days. The 3-year estimated rate was 93% for locoregional recurrence-free survival, 79% for distant disease-free survival, 79% for disease-specific survival, 64% for disease-free survival, and 67% for overall survival.

“As reported in other series with IMRT, we can offer very good locoregional control,” Dr. Yao commented on these rates. “However, more patients fail distantly, and this leads to poor overall survival.”

Univariate analyses did not show any significant associations between primary tumor SUV and outcomes, but they did show a significant association between SUV of the lymph nodes and distant disease-free survival (P = .03). Patients having SUV lymph node values less than 11.3 had a 3-year rate of distant disease-free survival of 82%, whereas those with higher values had a rate of 63%.

Multivariate analyses showed that higher SUV primary tumor values independently predicted poorer disease-specific survival (P = .045) and marginally predicted poorer overall survival (P = .051). Also, higher SUV of the lymph nodes independently predicted poorer distant disease-free survival (P = .03).

Receiver operating characteristic curve analysis failed to show a cutoff for SUV of the lymph nodes that performed well for identifying patients who developed distant metastases, according to Dr. Yao. But the combination of an SUV of the lymph nodes of 13 or higher and T4 stage had a sensitivity of 80% and a specificity of 64% for such identification.

“SUV of the lymph nodes may serve as an imaging biomarker for selecting patients for more aggressive systemic chemotherapy,” he concluded. “Further research, especially with additional markers, is necessary.”

Commenting on the study in a related press briefing, Dr. Michael Graham said, “By doing PET imaging before [treatment], you not only gain all of the information we gain [regarding] the staging of the cancer – where the cancer is and how extensive it is – but also how metabolically active it is.

“That can make a significant difference in how aggressively you want to treat the cancer, and this is likely to make a real difference in the care of the patients,” said Dr. Graham, a radiation oncologist at the University of Iowa, Iowa City, Iowa, and president of the Society of Nuclear Medicine.

Source: Elsevier Global Medical News. 2010 Mar 9, S London