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Objective:
Lung-RADS is a quality assurance tool standardizing lung cancer screening CT reporting and nodule management recommendations. As the Lung-RADS score increases, so does the estimated risk of lung malignancy. We sought to investigate the percentage of Lung-RADS 3 and 4 cases diagnosed with cancer in our screening program and the patient demographics and tumor characteristics associated with such.

Materials and Methods:
4,919 lung cancer screens were performed between January 2014 and December 2022. We sought the answers to 5 questions: (1) What percentage of our Lung-RADS 3 and 4 patients are diagnosed with lung cancer? (2) What are the demographics of those diagnosed? (3) What is the incidence of lung cancer in our program? (4) What is the most common lobar location of the cancer? (5) What is the most common cell type, average tumor size and stage of the cancer diagnosed in our program? The variables of interest were adjusted to be consistent across all patients to make the analyses easier and to correct for inconsistencies in reporting. Only Lung-RADS 3, and 4A, B, and X cases were reviewed. Regarding lobe location, a similar method was used, though some patients had multiple lobes involved. Cancer stage was reported as stage I-IV ignoring a, b, and c subdivisions. Only the largest tumor dimension in centimeters was extracted. Race was consolidated into white, black, and other. All data was cleaned and reported using SAS.

Results:
59 lung cancers were diagnosed. 52 of these received a Lung-RADS 4A, B, or X score on baseline reads. Regarding our 5 posed study questions: (1) Cancer diagnoses were made in 0.81% of patients with Lung-RADS 3 scores, and in 8.6%, 31%, and 43.3% of those with Lung-RADS 4A, B, and X scores, respectfully. (2) 56% of patients diagnosed with lung cancer were White, 39% Black, and 5% were other races. 50.9% were male and 49.1% were female. The median age at diagnosis was 64-years. (3) Analyzing our entire lung screening cohort, approximately 1.20% of screens resulted in positive lung cancer diagnoses (59/4919 = 0.0120). (4) Most cancers, 27.8%, were in the right upper lobe; 24% in the left upper lobe; 18.5% in the left and right lower lobe; 1.9% in the middle lobe; and 9.3% had synchronous cancers in more than one lobe. (5) The most common cell type was adenocarcinoma (51%) followed by squamous cell (29.5%) and small cell 13.1%. The average tumor size at diagnosis was 2.54 cm (SD 1.78 cm). 52.8% were diagnosed with stage I but 20.8% already had stage IV disease.

Conclusion:
Most lung cancers in our screening program occurred in younger patients with a Lung-RADS 4A, B or X score. There was a relatively equal number of men and women diagnosed with lung cancer. Most cases were stage I adenocarcinoma, but nearly one-fifth of screenees had stage IV disease, and about 9% of screenees had synchronous cancers affecting more than one lobe. Knowledge of this pattern and presentation of disease on screening exams will aid both radiologists and clinicians in diagnosing lung cancer.