High standard uptake value (SUVmax) for fluorodeoxyglucose (FDG) avidity in primary lung cancer is associated with aggressive disease. Here we have hypothesised that correction of SUVmax for tumour size enables clinically useful identification of small high-SUVmax lung tumours with bad prognosis, and/or large low-SUVmax tumours with good prognosis.
Data from 615 patients were downloaded from the lung cancer database 2007-2014. Of these, we identified 204 cases of adenocarcinoma or squamous cell carcinoma (SCC) for which correlative FDG-PET scan data were available. To assess the relationship of SUVmax to histology and stage independent of size, we derived a new parameter, size-corrected SUV (scSUV). Statistics were generated using SPSS software.
A linear relationship was shown between SUVmax and tumour size (p < 0.0001, R = 0.6); moreover, late-stage tumours were associated with higher SUVmax (p < 0.001) and size (p = 0.001) than early-stage tumours. Both a higher SUVmax (p = 0.001) and size (p < 0.001) were found for SCC vs. adenocarcinoma. When these relationships with stage and histology were re-analyzed using scSUV instead of SUVmax, however, no significant trend was evident (p = 0.98 and p = 0.1, respectively). Consistent with this, very few small high-SUVmax or large low-SUVmax tumours could be identified.
We submit that primary lung cancer SUVmax does not vary independently of tumour size to any clinically useful extent. This suggests in turn that primary lung tumour size can be more accurately equated with the biologic aggressiveness of the disease than with delayed time to diagnosis.
Clinical trial identification
All authors have declared no conflicts of interest.