Pulmonary cancer screening: volumetric thresholds of nodules surpass the diameter measurements. A vast British study demonstrates their effectiveness to reduce unnecessary exams and personalize management.
The performance of the volume and diameter thresholds of the pulmonary nodules detected in the context of detection of bronchopulmonary cancer by chest toad à irradiation (TDTFI), as well as optimal monitoring strategies, are not clearly established.
A large British observational study, more than 11,000 participants
AW Creamer et al. Analyze in a vast British observational study the performance of dimensional thresholds (diameter and volume) of solid pulmonary nodules and the profitability of a strategy for the risk of malignancy in an asymptomatic population at high risk of bronchopulmonary cancer.
The analysis focused on 11,355 median age participants of 65 (IQR 60-70) years, mainly male (57.7 %), strongly smoking (40.5 packages-years [32,3 – 51,0] Packages – Years). Each participant benefited from a TDTFI in inclusion and then at least 2 years later. The nodules were characterized by their diameter and volume thanks to dedicated software (Veolity, Mevis).
The thresholds tested were:
-Exclusion of malignancy: diameter of 5-6 mm and volume of 80-100 mm≥
– suspicion of malignancy: diameter ≥ 8 mm and volume ≥ 300 mm≥.
These thresholds were supplemented by the Brock (SB) score which assesses the Malignity Surryque.
Among the 5,929 subjects with a pulmonary nodule with the initial scanner, 228 nodules were clever confirmed (gross risk 3.85 % [IC95 : 3,37-4,37 %]). In the absence of an initial pulmonary nodule, 37 cancers occurred during follow -up (gross risk 0.77 %, [0,54-1,06 %]).
Performance of different strategies
Regarding the exclusion strategy (performance of the thresholds to consider a nodule as benign): the risk of cancer for a nodule in diameter <6 mm or volume <100 mm≥ equivalent to the risk of cancer in the absence of a nodule on 1is Tdtfi (0,88% and 0.81% versus 0.77%, ns). The 5 mm diameter threshold does not significantly improve sensitivity compared to 6 mm, while degrading specificity (24.6 % vs 41.3 %). The threshold of 100 mm still was as efficient as that of 80 mm≥.
An advantage of the volumetric thresholds was noted: for thresholds of 80 mm≥ versus 5 mm, the negative predictive values were identical (99 %), but the specificity of the volume was very higher (65.4 % vs 24.6 %). The volumetric threshold therefore made it possible to conclude with safety in benignity in 20 % of additional patients from the first examination.
The characterization strategy (performance to suspect malignancy beyond the thresholds) also showed the superiority of the volumetric threshold. The sensitivity of the millimeter measurement was greater than that of the volumetric measurement (77.6 % against 66.7 %; p <0.0001) while the specificity of the volumetric measure was significantly greater than the millimeter (93.7 % against 70.6 %; p <0.0001).
The Brock score allowed stratification: a value <10 % leading to the realization of an intermediate scanner at 1 year, a value ≥ 10 % leading to the realization of a TEP-TDM. This score significantly improved the selection of patients requiring additional explorations, especially for the 8 mm threshold.
The authors recall that in 2 % of cases approximately the measurement of the volume of the nodule is technically impossible. Thus, the SB allows you to personalize monitoring by orienting patients at intermediate risks to a CT or a PET depending on the level of suspicion.
This study confirms the efficiency of TDTFI screening (identification of 228 cancers out of 5,929 high -risk subjects, or almost 4 %). It demonstrates the superiority of volumetric thresholds to dismiss malignancy, reduce false positives and optimize monitoring. The integration of the Brock score makes it possible to individualize the diagnostic route more, orienting management according to the level of risk.
