FDG PET-CT SUVmax and IASLC/ATS/ERS histologic classification: a new profile of lung adenocarcinoma with prognostic value.

Quantitative analysis of glucose consumption measured by maximum standardized uptake value (SUVmax) in lung adenocarcinoma (LA) remains in discussion and metabolic information provided by FDG-PET is not included in cancer staging. The first aim of this work was to evaluate the correlation between SUVmax and different histologic subtypes of LA. The second aim was to establish the correlation between SUVmax and TNM, genetic mutations and prognostic. Glucose consumption of primary tumor was quantified using SUVmax in 112 patients with histologically-confirmed LA. Specimens were classified according to the IASLC/ATS/ERS into in situ -AIS-, minimally invasive -MIA-, invasive (lepidic, papillary, acinar, solid and micropapillary) and invasive mucinous adenocarcinoma. Tumors were grouped according to three histological grades; low-grade: AIS, MIA, intermediate-grade: lepidic, acinar, papillary and high-grade: micropapillary, solid and mucinous. Comparisons between SUVmax and histologic subtypes were performed with Kruskal-Wallis followed by a Dunn's test. Overall (OS) and disease-free survival (DFS) were calculated. SUVmax was histologically-dependent (P<0.001): AIS 0.5±0.1, MIA 1.1±0.9 lepidic 3.3±3.1, acinar 8.6±6.7, papillary 3.9±5.1, micropapillary 4.9±3.4, solid 10.4±5.4 and invasive mucinous 2.7±1.2. SUVmax was associated with TNM stage in stage IA and IB. SUVmax was significantly lower in patients with K-RAS and EGFR mutation. Low SUVmax was associated with low-grade histology and with a higher OS and DSF compared to high SUVmax (intermediate and high-grade histology). SUVmax on FDG-PET is a powerful information in the presurgical evaluation of LA patients. It provides prognostic data and should be considered in the staging algorithm of patients with LA.