PET does not predict survival in advanced lung cancer

Nov 28, 2007

CHICAGO - Studies over the past several years have demonstrated FDG-PET's ability to predict survival in patients with early-stage lung cancer. But for those with advanced non-small cell lung cancer (NSCLC), PET has no prognostic value, according to a new 15-year study from Duke University Medical Center in Durham, NC.

"FDG-PET has become well-established for evaluating patients with lung cancer -- both for diagnosis, where it can differentiate benign from malignant nodules, and also for staging following a diagnosis of lung cancer," said researcher Jenny Hoang in a presentation at the RSNA 2007 meeting. "More recently it has been suggested that FDG may have an additional role providing prognostic information for patients."

Recent studies of early-stage NSCLC have found that higher FDG uptake corresponds to tumor doubling time and survival (Cerfolio et al, Sasaki et al). Still, Hoang said, there are no studies evaluating tumor uptake and survival in patients with advanced NSCLC, despite the fact that advanced disease is more common than early-stage disease at presentation.

In their study, Hoang and her colleagues sought to determine if the maximum standardized uptake value (SUVmax) on FDG-PET in patients with advanced NSCLC also correlated with survival.

They performed a retrospective review of the Duke University tumor registry in 214 patients (130 men, 84 women) with advanced NSCLC (stages IIIa, IIIb and IV), acquired from January 1992 to December 2000 and followed until March 2007. Ninety-three of the 214 patients had stage IV disease, and most had undergone both chemotherapy and radiotherapy treatment.

Based on patients' medical records, the team recorded tumor histological cell type, clinical and pathological stage at presentation, the site of metastasis, and treatment.

Specifically, they used SUVmax in the primary tumor to quantitatively determine FDG-PET activity. The end point, survival time, was obtained from the tumor registry and verified with the medical records.

According to the results, mean survival time was 15 months (range 0-139). Of the 189 patients' results reported by the authors in their abstract, 56 patients who survived 24 months or longer had median SUVmax of 9.65 (range 2.49-36.81). Among the 73 subjects who died during the first 12 months, the median SUVmax was 11.48 (range 2.32-24.772).

For the group with SUVmax greater than 10 in the primary tumor, median survival time was 15 months (range 0-95). For those with SUVmax less than 10, median survival was 17 months (range 0-139). The survival curves were similar for both groups, and the correlation co-efficient for SUVmax and survival was -0.067 (p < 0.36).

As for study limitations, the retrospective review was conducted over a long period of time with patients who underwent different treatments, Hoang said. However, since no treatment regimen has been found to extend the lives of advanced NSCLC patients, the slight differences in patient management were unlikely to have had a significant impact, she said. Another potential limitation was selection bias due to the lack of consecutive patient enrollment, inasmuch as only advanced-stage patients were included in the study.

"In contrast to early-stage NSCLC, for advanced stage disease, FDG uptake in the primary tumor does not correlate to survival," Hoang concluded. "And the implication here is that we should not use the uptake in FDG-PET imaging to advise physicians or patients with advanced non-small cell lung carcinoma."

Similarly, Hoang said in response to a question, tumor size was not a significant factor in the survival of these patients.

By Eric Barnes
AuntMinnie.com staff writer
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