AR: Quantitative PET/CT data offer prognostic measurement for lung cancer
Baseline whole-body tumor burden provided a prognostic measurement in patients with Stage IV nonsurgical non-small-cell lung cancer (NSCLC) with low interobserver variability, according to a study published in the January 2012 issue of Academic Radiology.

Stage IV NSCLC comprises a heterogeneous group of patients often treated with different strategies. Prognosis and five-year survival for this group are poor, and clinicians struggle to stratify patients into different prognostic and treatment groups. Existing prognostic measures rely on surgical resectability rather than metabolic volumetric information from PET/CT data.

Shengri Liao, MD, from the department of radiology at University of Chicago, and colleagues sought to determine the prognostic utility of metabolic volumetric measurement in patients with Stage IV NSCLC and compared metabolic tumor volume (MTV) and total lesion glycolysis (TLG) with standard uptake value (SUV) measurements.

The researchers identified 92 consecutive nonsurgical patients with Stage IV NSCLC from a retrospective database who were imaged via PET/CT between January 1, 2004 and December 31, 2007.

A pair of radiologists calculated MTV and TLG as well as SUVmax and SUVmean. A third radiologist analyzed data from a subset of 30 patients to assess interobserver variability.

Liao and colleagues wrote, “There was a consistent association of high values of MTV, TLG and SUVmax at the levels: whole-body tumor burden, primary tumor, nodal and distant metastases with short median overall survival months and lower one- and two-year survival rates.”

After further analysis and adjustment for age and gender, the researchers determined that MTV and TLG are prognostic indices at the levels of whole-body tumor burden level and primary tumor.

Although the researchers did not find a significant prognostic value for SUV parameters, they noted that these measurements do provide some value and some previous studies of NSCLC patients have suggested a prognostic role for SUV measurements.

Liao and colleagues referred to several limitations to the approach. Specifically, measuring all of the tumors in the body is time-consuming, they wrote. However, improved software should address this challenge, they continued. An advantage of the approach is its low interobserver variability.

The researchers concluded by emphasizing the prognostic value of baseline whole-body metabolic tumor burden and added, “This study also suggests pretreatment MTV and TLG values may be used to further stratify patients with Stage IV NSCLV and may be better prognostic measures than SUVmax and SUVmean measurements.” However, this approach requires validation in larger cohorts in a prospective study.