Edward Patz

M.D.

Duke University School of Medicine

Professor of Radiology, Professor in Pathology, Professor in Pharmacology & Cancer Biology

NLST (Learn more about this study)

NLST-541

Jul 17, 2019

Is 6 month an appropriate follow-up interval for LungRADS category 3 cases?

The Lung-RADS is a risk-stratifying system proposed by the American College of Radiology (ACR) Lung Cancer Screening Committee subgroup for screening chest CT. Among its categories (CAT), CAT1 and CAT2 are considered negative results. Currently, recommended management plan for a case belonging to CAT3 (5 % of population, estimated cancer rate of 1-2 %) is "repeat CT 6 months later".

Based on our own practice experience, however, the vast majority of CAT3 patients undergo repeat CTs until much later than 6 months since the baseline screening CT. In other words, most of CAT 3 patients seem to undergo repeat CT up at least for 12 months without undergoing invasive diagnostic procedures or therapy. As a result, the actual management of a CAT3 nodule may be often identical to that of a CAT2 nodule, except additional, possible futile, CT exam at 6 month. We aim to assess how often this is the case in the entire CAT3 individuals, and then identify what type of CAT3 subgroup (according to density, cell type) is similar to CAT2 in terms of the diagnostic work up , treatment history, and prognostic parameters and thus can possibly be managed similarly.

- Review CT images of 290 part-solid nodule cases that appear in Table 2 of the article "Performance of Lung-RADS in the National Lung Screening Trial : A Retrospective Assessment (published at Ann Intern Med. 2015;162:485-491. doi:10.7326/M14-2086)" as "3 or 4A (n=97)" and "3, 4A, or 4B (n=193)", respectively, in order to discern which of them can be truly assigned CAT3.

- Return the results back to NLST, enabling NLST to update the LungRADS category data of the NLST population.

- Receive all data that had been collected by NSLT through form DE (in LSS ; form ZX in ACRIN), SPIRAL CT SCREENING EXAMINATION FORM (in LSS, form I9, 4 in ACRIN), Form TI (in LSS ; form TF in ACRIN), Form CP (in LSS; form CS in ACRIN) for individuals who were either CAT2 or (updated) CAT3 at Baseline. Of CAT2 cases, only those in which LungRADS-category-defining nodule was 4 mm or greater are included. Refer to the Pinsky et. al. article for definition of Baseline

- Plot and compare various diagnosis-related, treatment-related, survival related parameters between CAT 2 and CAT3 as well as between CAT2 and CAT3 subgroups (explained later) : Number, Cancer rate, Time to the first non-imaging work up, Time to lung cancer diagnosis (LSS, DE Part C 8 ; ZX, 7), Time to the first mention of growth or Interval suspicious change in attenuation (whichever comes first) at regular screening T1, T2, or T3 (LSS, SPIRAL CT SCREENING EXAMINATION FORM, Part E2 ; I9, 4), Time to first biopsy or cytologic procedure, Time to the first local therapy (surgery, definitive RT, preoperative RT (whichever comes first) ; TI in LSS, TF in ACRIN), The rate of and time to post-treatment progression (form CP in LSS; form CS in ACRIN), Kaplan-Meier survival curves.

- Subgroup analysis 1 (NSCLC filter): First, exclude all small cell lung cancer cases from population and then to conduct comparison between CAT 2 and CAT3 as well as between CAT2 and CAT3 subgroups for above parameters

- Subgroup analysis 2 (density filter) : First, exclude all nonsolid cases (cases in which LungRADS-category-defining nodule is of a nonsolid density) and then conduct comparison between CAT 2 and CAT3 as well as between CAT2 and CAT3 subgroups for above parameters ; Second, exclude both part-solid and nonsolid cases and then conduct comparison between CAT 2 and CAT3 as well as between CAT2 and CAT3 subgroups for above parameters. Density parameters are available at Form SPIRAL CT SCREENING EXAMINATION FORM part C2 : Predominant Attenuation (in LSS; From C2, Part B12 in ACRIN).

- Look for CAT3 subgroup(s) with similar profiles to those of CAT2 ; Suggest 12-month-follow up-policy for them

Dae Hee Han ( Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Republic of Korea)

Hyae Young Kim ( Department of Radiology, National Cancer Center, Republic of Korea )

Jin Mo Goo ( Department of Radiology, Seoul National University Hospital, Republic of Korea )