Table 1.

C-Lung-RADS assessment categories

C-Lung-RADS	Category descriptor	Findings	Management	Risk of malignancy	Estimated population prevalence
0	Negative	Calcifications	Continue annual screening with LDCT in 12 months	–	–
1	Low risk	Solid nodule: • <6 mm	Continue annual screening with LDCT in 12 months	0.3%	78.2%
		Part-solid nodule (mGGN): • <6 mm
		Non-solid nodule (pGGN): • <6 mm
2	Mid risk	Solid nodule: • ≥6 to <10 mm	Six-month CT	3.2%	17.4%
		Part-solid nodule (mGGN): • ≥6 mm total mean diameter with solid component <6 mm
		Non-solid nodule (pGGN): • ≥6 to <20 mm
3	High risk	Solid nodule: • ≥10 to <18 mm	Three-month CTa	6.2%	2.6%
		Part-solid nodule (mGGN): • ≥6 mm total mean diameter with solid component ≥6 to <10 mm
		Non-solid nodule (pGGN): • ≥20 mm
4	Extremely high risk	Solid nodule: • ≥18 mm	Immediate clinical assessmentb	24.3%	1.8%
		Part-solid nodule (mGGN): • Solid component ≥10 mm
		Category 2 or 3 nodules with a multidimensional model-predicted malignant probability ≥0.5

^aFor label 3 nodules, high-resolution CT or PET/CT may be considered.

^bFor label 4 nodules, a comprehensive clinical assessment is warranted, which may include a diagnostic chest CT with or without contrast enhancement, PET/CT scanning particularly when there is a solid nodule or solid component measuring 8 mm or larger, tissue sampling such as biopsies, and/or referral for additional clinical evaluation. The decision to proceed with these assessments should be based on a careful clinical evaluation, taking into account the patient’s preferences and the estimated likelihood of malignancy.