Implications of Use of Two Protocols and Methods of Nodule Measurement on Workup of Positive Findings in Lung Cancer Screening

Dorith Shaham Eliezer Terespolsky
Radiology, Hadassah Hebrew University Medical Center, Israel

BACKGROUND: Several protocols guide the management of positive findings on low-dose CT screening for lung cancer, in order to minimize unnecessary workup. We aimed to compare the recommendations for workup based on two protocols, I-ELCAP and Lung-RADS , and to investigate the implications of using different methods for measuring of pulmonary nodule size on the rate of positive findings and, consequently, on the rates of additional follow-up exams.

METHODS: The effect of using either I-ELCAP or Lung-RADS protocol on workup recommendations was evaluated by applying each protocol to all 105 available cases which included at least one non-calcified nodule ≥5.5 mm in our database of 1233 cases. Two nodule measurement methods were also applied to the eligible cases, and were evaluated independently for each of the two protocols. Comparison between protocols and the methods of measurement were analyzed by the McNamer test.

RESULTS: The follow-up recommendations according to the I-ELCAP protocol were significantly inconsistent (p < 0.001) with the Lung-RADS recommendations, mostly due to the significantly higher recommendation rate for PET-CT by Lung-RADS (p < 0.001). Measuring of only the maximal diameter of the nodule vs. the average of maximal diameter and width, resulted in a higher rate of recommendations for invasive procedures. These differences weres significant for each of the protocols (Lung-RADS and I-ELCAP) separately (p< 0.001). The difference in the recommendations when rounding up to the next millimeter vs. avoiding rounding up, was significant for both I-ELCAP (p <0.011) and Lung-RADS (p <0.018).

CONCLUSION: Application of the I-ELCAP protocol and a policy that doesn`t support rounding up of nodule size may reduce the rate of unnecessary workup and prevent collateral harm. A measurement method that considers only the maximal diameter results in a higher invasive procedure rate.

Dorith Shaham
Prof. Dorith Shaham
Hedassah-Hebrew University Medical Center