Abstract
To investigate whether 18F-fluoro-2-deoxy-glucose positron emission tomography (FDG-PET) may be a potential tool to select a subgroup of patients who might be spared maintenance treatment, if the metabolic response after first-line chemotherapy could predict time-to-progression (TTP). A total of 43 patients who underwent baseline FDG-PET scan and did not show disease progression (DP) after 4 cycles of first-line chemotherapy were enrolled and underwent second FDG-PET 3 weeks after completion of the first-line chemotherapy. The primary endpoint was to compare percent decrease in maximum standard uptake value (SUVmax) between early (TTP after second PET examination <8 weeks) and late (TTP ≥8 weeks) DP subgroups. Secondary endpoints were to determine whether fractional decrease in SUVmax could predict TTP and overall survival (OS), both calculated from the date of the second FDG-PET. Percent decreases in SUVmax in late DP subgroup were greater than those in early DP subgroup (mean reduction, 54.7% ± 27.2% vs. 27.8% ± 46.8%, P = 0.021). Receiver operating characteristic curves identified a 50.0% decrease in SUVmax as the optimal threshold to distinguish these subgroups. Using this value as the cutoff resulted in a positive predictive value of 82.6% and negative predictive value of 60.0% in predicting TTP ≥8 weeks. Patients with SUVmax decrease <50% had significantly longer median TTP (3.0 vs. 1.5 months, P = 0.001) and OS (not reached vs. 14.2 months, P = 0.003). Fractional decrease in SUVmax of the main lesion after completion of 4 cycles of chemotherapy may discriminate patients with TTP ≥8 weeks and predict TTP and OS in patients with advanced NSCLC.
Highlights
Platinum-based doublet regimens have been a mainstay of first-line treatment of patients with advanced non–small cell lung cancer (NSCLC) since a landmark meta-analysis clearly showed a significant survival benefit compared with best supportive care [1, 2]
Receiver operating characteristic curves identified a 50.0% decrease in SUVmax as the optimal threshold to distinguish these subgroups. Using this value as the cutoff resulted in a positive predictive value of 82.6% and negative predictive value of 60.0% in predicting TTP !8 weeks
The 2009 American Society of Clinical Oncology guidelines recommended no further chemotherapy after first-line chemotherapy prior to disease progression (DP) for patients who have stable disease or who respond to first-line therapy [3, 4]
Summary
Patient characteristics Between December 2007 and November 2008, 43 patients with stage IV NSCLC were enrolled (Table 1). A second FDG-PET examination after first-line chemotherapy seems useful in discriminating early and late DP subgroups and predicting both TTP and OS in patients with advanced NSCLC. A 50% or more decrease in SUVmax, as the threshold for a FDG-PET response, could differentiate patients into early and late DP subgroups, with a PPV of 82.6% for the prediction of late DP This indicates that at least more than 80% of patients do not progress early without maintenance chemotherapy if their fractional decrease in SUVmax exceeds 50%. Fractional decrease in SUVpeak was significantly higher in the late DP group and 50% decrease in SUVpeak following primary chemotherapy could distinguish the late DP from the early DP group with a PPV of 80.0%, which are consistent with results from SUVmax change. This fractional change in SUVmax or SUVpeak may be a better cutoff than absolute value because the SUV thresholds identified in singleinstitution studies involving a specific set of patients may not be applicable to other institutions with different
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