Lung cancer diagnosis rates (LCDR) in lung cancer screening (LCS) and incidental pulmonary nodule (IPN) cohorts in the Mississippi Delta.

Abstract

8002 Background: The LCDR in the CT screened cohort in the National Lung Screening Trial (NLST) was 1.1% over a median of 6.5 years follow up. We evaluated the LCDR in a regional US community. Methods: Prospective cohort study of patients in LCS and IPN programs in 22 facilities across a 125 county service area population. We compared LCDR over 3 years in LCS stratified by Lung-RADS (L-R) score (1 to 4X), IPN by nodule size (≤6, >6-15, >15-20, >20-30 mm) on initial CT scans. Comparisons used Chi-square tests, Wilcoxon tests, and Cox regression models with Hazard Ratios (HR) for lung cancer diagnosis adjusted for age, sex, race, and insurance. Results: From 2015 to 2023, 7121 persons were enrolled in LCS – 5447 (76%) L-R 1/2, 823 (12%) L-R 3, 452 (6%) L-R 4A, 205(3%) L-R 4B, and 114(2%) L-R 4X; and 22,455 in IPN - 8141 (36%) ≤6mm, 11177 (50%) >6-15 mm, 1596 (7%) >15-20 mm, 1535 (7%) >20-30 mm. Over this period, 334 (4.7%) and 1016 (4.5%) were diagnosed with lung cancer in LCS and IPN cohorts, respectively, including 91 (2%), 40 (5%), 60 (13%), 68 (33%), and 66 (58%) L-R 1-4X and 69 (1%), 421 (4%), 224 (14%) and 302 (20%) of IPN cohort in ascending order of nodule size. The cumulative LCDR at 36 months were: 5% (95% CI 4.4 – 5.6) in LCS- 1.9% (1.5-2.4), 5.0% (3.4-7.0), 14%(10-18), 33%(27-40), and 60% (49-68) for L-R 1 to 4X, respectively; and 4.4% (4.1 – 4.7)- 0.66% (0.49-0.88), 3.5% (3.2-3.9), 14% (12-16) and 20% (18-22) for the respective IPN cohorts. With L-R 1/2 as reference, aHR for lung cancer diagnosis was 2.9 (2.0 - 4.1, p<0.0001), 7.6 (5.4 - 10.6, p<0.0001), 24.1 (17.4 - 33.4, p<0.0001), and 66.3 (47.7 - 92.3, p<0.0001) for L-R 3, 4A, 4B & 4X in LCS cohort. With nodule >6-15 as reference, aHR was 0.2 (0.2 - 0.3, p<0.0001), 4.2(3.6 - 4.9, p<0.0001) and 5.7 (4.9 - 6.7, p<0.0001) in IPN cohort. Conclusions: LCDR of this Mississippi Delta LCS and IPN cohort was greater than 4-fold the NLST. The NLST significantly underestimates the potential impact of LCS in this population. LCS IPN 1-2 3 4A 4B 4X P 0-6mm 6-15 15-20 20-30 P N = 5447 N = 823 N = 452 N = 205 N = 114 N = 8147 N = 11177 N = 1596 N = 1535 Lung Cancer* 91 (2) 40 (5) 60 (13) 68 (33) 66 (58) <0.0001 69(1) 421(4) 224 (14) 302(20) <0.0001 Age Median (Q1 - Q3) 65 (60-70) 65 (60-70) 67 (61-71) 67 (63-73) 67 (63-72) <0.0001 62 (51-72) 64 (52-74) 66 (53-75) 68 (57-77) <0.0001 Female* 2795 (51) 400 (49) 218 (48) 107 (52) 57 (50) 0.4709 4777(59) 6191 (55) 884 (55) 788 (51) 0.0005 Black* 1005 (19) 157 (19) 87 (19) 37 (18) 25 (22) 0.972 2376(29) 3126 (28) 479 (30) 443 (29) 0.0713 Commercial insurance* 2168 (40) 297 (36) 142 (31) 58 (28) 30 (26) 0.0005 3612(44) 4544 (41) 596 (37) 515 (34) 0.0005 Never smoked* 13 (0.2) 3 (0.4) 0 0 0 0.4628 3662(45) 4537 (41) 549 (34) 474 (31) 0.0005 Adenocarcinoma** 31 (34) 15 (38) 29 (48) 31 (46) 44 (67) 0.075 24(35) 222 (53) 130 (58) 164 (54) 0.0235 Clinical stage I/II** 58 (64) 26 (65) 48 (80) 49 (72) 40 (61) 0.3168 29(42) 255 (61) 141 (63) 183 (61) 0.14 *N (%). **Denominator is # of lung cancer patients.