Accuracy of CT parameters for assessment of tumour size and aggressiveness in lung adenocarcinoma with bronchoalveolar elements

Abstract

Accurate determination of tumour size in lung adenocarcinoma with bronchoalveolar features (BAC) is important for the determination of TNM (tumour, nodes, metastasis) scores used in staging, prognosis and therapy response assessment. However, tumour sizes derived using lung window (LW) CT or soft-tissue/mediastinal window (MW) CT often give different results. This study examines which measurement correlates best with actual tumour size and which best identifies advanced disease. This retrospective study included 43 BAC patients who underwent surgical resection with mediastinal lymphadenectomy <4 weeks post CT scan. The largest unidimensional tumour diameter on each CT window was compared with actual histopathological tumour size (HP). LW, MW and HP size measurements and a recently described CT parameter - the modified tumour shadow disappearance rate (mTDR) = (1 - [MW/LW]) - were then used to determine which parameter best discriminated between the presence or absence of advanced disease. There was no difference between HP and LW sizes, but MW significantly underestimated HP size (p<0.0001). Unlike MW (p = 0.01) and mTDR (p = 0.001), neither HP (p = 0.14) nor LW (p = 0.10) distinguished between patients with or without advanced disease. On receiver operating characteristic (ROC) analysis at a cut-off of ≤0.13, the sensitivity and specificity of mTDR for detecting advanced disease were 69% and 89%, respectively. In patients with tumours ≤3 cm, only mTDR remained a significant predictor of advanced disease (p = 0.017), with best cut-off at ≤0.20, giving a sensitivity and specificity of 71% and 94%, respectively. MW better predicts advanced disease than LW and might also need to be recorded for RECIST (response evaluation criteria in solid tumours) assessment for T staging of BAC; however, mTDR appears to be an even better predictor and should also be used.

Detection and quantification of the solid component in pulmonary subsolid nodules by semiautomatic segmentation

“…Several other papers report on attempts for objective methods other than the calculation of GGO ratio and TDR to evaluate the quantitative aspects and characterization of an SSN [19][20][21][22][23][24]. Some use a one-dimensional analysis [22,24] by measuring the diameter or a combination of diameter and density of the components of an SSN on a one-dimensional histogram of the nodule.…”

Correlation between the Size of the Solid Component on Thin-Section CT and the Invasive Component on Pathology in Small Lung Adenocarcinomas Manifesting as Ground-Glass Nodules

“…components represent the lepidic growth and that solid components are frequently related with invasion [11][12][13][14][15][16][17][18][19][20][21][22][23] and also note that computed tomography (CT) plays an important role in the management of subsolid nodules. 10 It has also been suggested that the T staging in the Tumor Node Metastasis classification should be adjusted radiologically by measuring the solid component of subsolid nodules 1 and that the management of subsolid nodules should be based on the size of subsolid nodules and the solid component.…”

Paradigm shifts in lung cancer as defined in the new IASLC/ATS/ERS lung adenocarcinoma classification

“…Furthermore, it may be possible to improve TNM staging for lung adenocarcinomas that have a lepidic component by using the invasive size to predict tumour size rather than total size both by pathologic and CT assessment. There is already data in the pathology and CT literature that suggests this may be true [27][28][29][30]. If this turns out to be validated in future studies, in the next edition of the TNM it may be possible to use new terms for AIS and MIA, so Tis (adenocarcinoma) can be used for AIS and Tmi (adenocarcinoma) for MIA.…”