Re: Hong JC, Boyer MJ, Spiegel DY, et al. Increasing PET Use in Small Cell Lung Cancer: Survival Improvement and Stage Migration in the VA Central Cancer Registry. J Natl Compr Canc Netw 2019;17(2):127–139.
We read with interest the study by Hong et al1 on stage migration in small cell lung cancer (SCLC) after increased FDG-PET use. The authors postulate that this led to improved survival because appropriate treatment was delivered due to accurate staging provided by FDG-PET.
The authors should be commended for reporting data from a large retrospective cohort. However, as they acknowledged, there are many confounders and selection biases in this study that limit the ability to draw firm conclusions. For this reason, their findings do not provide sufficient evidence to support the routine clinical use of FDG-PET/CT in SCLC. The survival improvement reported over the course of the study could be due to improvements in supportive care or chemoradiotherapy delivery techniques, both unaccounted for in their analysis.
Hong et al compare their outcomes to those of the CONVERT trial,2 in which 57% of patients were staged with FDG-PET/CT in addition to conventional imaging (thorax/abdomen CT, brain imaging ± bone scintigraphy). We would like to note our recently published secondary CONVERT trial analysis that investigated the impact of FDG-PET/CT in limited-stage (LS) SCLC.3 Although patient characteristics were significantly imbalanced in favor of the FDG-PET/CT–staged group, we report that survival outcomes were not significantly different between patients staged with or without FDG-PET/CT, in contradiction to the findings by Hong et al.
Landmark trials that established chemoradiotherapy as standard treatment in LS SCLC were conducted before the FDG-PET/CT era.4 Furthermore, the CONVERT trial did not mandate FDG-PET/CT staging.2 Data from the CONVERT FDG-PET/CT secondary analysis support that patients with SCLC without metastatic disease detected on CT may benefit from curative-intent chemoradiotherapy. Arguably, a proportion of these patients had low-burden metastatic disease undetected on CT. Caution is therefore required in the interpretation of the findings by Hong et al, because the routine use of FDG-PET/CT could deny these patients appropriate, evidence-based therapies.
Unfortunately, both the study by Hong et al and the CONVERT FDG-PET/CT secondary analysis do not provide level 1 evidence to support the use or omission of FDG-PET/CT for treatment selection in SCLC. A randomized controlled trial is required to settle this debate. However, in our view, there is little interest in conducting such a trial among the oncology and imaging communities. We encourage continued debate and reflection of published data regarding the impact of imaging on improving outcomes of patients with SCLC.
Hong JC, Boyer MJ, Spiegel DY, . Increasing PET use in small cell lung cancer: survival improvement and stage migration in the VA Central Cancer Registry. J Natl Compr Canc Netw 2019;17:127–139.
Faivre-Finn C, Snee M, Ashcroft L, . Concurrent once-daily versus twice-daily chemoradiotherapy in patients with limited-stage small-cell lung cancer (CONVERT): an open-label, phase 3, randomised, superiority trial. Lancet Oncol 2017;18:1116–1125.
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)| false . , Faivre-Finn C , Snee M , Ashcroft L Concurrent once-daily versus twice-daily chemoradiotherapy in patients with limited-stage small-cell lung cancer (CONVERT): an open-label, phase 3, randomised, superiority trial. Lancet Oncol 2017; 18: 1116– 1125. 28642008 10.1016/S1470-2045(17)30318-2
Manoharan P, Salem A, Mistry H, . [18F]fludeoxyglucose PET/CT in small-cell lung cancer: analysis of the CONVERT randomized controlled trial. J Thorac Oncol 2019;14:1296–1305.
Thomson D, Hulse P, Lorigan P, Faivre-Finn C. The role of positron emission tomography in management of small cell lung cancer. Lung Cancer 2011;73:121–126.