Table 5. Stage and Histologic Type of Lung Cancers in the Two Screening Groups, According to the Result of Screening*.
| Stage and Histologic Type | Low-Dose CT | Chest Radiography | ||||||
|---|---|---|---|---|---|---|---|---|
| Positive Screening Test (N=649) | Negative Screening Test (N = 44)† | No Screening Test (N=367)‡ | Total (N = 1060) | Positive Screening Test (N = 279) | Negative Screening Test (N = 137)† | No Screening Test (N = 525)‡ | Total (N=941) | |
| number/total umber (percent) | ||||||||
| Stage | ||||||||
| IA | 329/635 (51.8) | 5/44 (11.4) | 82/361 (22.7) | 416/1040 (40.0) | 90/275 (32.7) | 16/135 (11.9) | 90/519 (17.3) | 196/929 (21.1) |
| IB | 71/635 (11.2) | 2/44 (4.5) | 31/361 (8.6) | 104/1040 (10.0) | 41/275 (14.9) | 6/135 (4.4) | 46/519 (8.9) | 93/929 (10.0) |
| IIA | 26/635 (4.1) | 2/44 (4.5) | 7/361 (1.9) | 35/1040 (3.4) | 14/275 (5.1) | 2/135 (1.5) | 16/519 (3.1) | 32/929 (3.4) |
| IIB | 20/635 (3.1) | 3/44 (6.8) | 15/361 (4.2) | 38/1040 (3.7) | 11/275 (4.0) | 6/135 (4.4) | 25/519 (4.8) | 42/929 (4.5) |
| IIIA | 59/635 (9.3) | 3/44 (6.8) | 37/361 (10.2) | 99/1040 (9.5) | 35/275 (12.7) | 21/135 (15.6) | 53/519 (10.2) | 109/929 (11.7) |
| IIIB | 49/635 (7.7) | 15/44 (34.1) | 58/361 (16.1) | 122/1040 (11.7) | 27/275 (9.8) | 24/135 (17.8) | 71/519 (13.7) | 122/929 (13.1) |
| IV | 81/635 (12.8) | 14/44 (31.8) | 131/361 (36.3) | 226/1040 (21.7) | 57/275 (20.7) | 60/135 (44.4) | 218/519 (42.0) | 335/929 (36.1) |
| Histologic type | ||||||||
| Bronchioloalveolar carcinoma | 95/646 (14.7) | 1/44 (2.3) | 14/358 (3.9) | 110/1048 (10.5) | 13/276 (4.7) | 1/135 (0.7) | 21/520 (4.0) | 35/931 (3.8) |
| Adenocarcinoma | 258/646 (39.9) | 8/44 (18.2) | 114/358 (31.8) | 380/1048 (36.3) | 112/276 (40.6) | 37/135 (27.4) | 179/520 (34.4) | 328/931 (35.2) |
| Squamous-cell carcinoma | 136/646 (21.1) | 13/44 (29.5) | 94/358 (26.3) | 243/1048 (23.2) | 70/276 (25.4) | 24/135 (17.8) | 112/520 (21.5) | 206/931 (22.1) |
| Large-cell carcinoma | 28/646 (4.3) | 3/44 (6.8) | 10/358 (2.8) | 41/1048 (3.9) | 12/276 (4.3) | 10/135 (7.4) | 21/520 (4.0) | 43/931 (4.6) |
| Non-small-cell carcinoma orother§ | 75/646 (11.6) | 4/44 (9.1) | 52/358 (14.5) | 131/1048 (12.5) | 40/276 (14.5) | 30/135 (22.2) | 88/520 (16.9) | 158/931 (17.0) |
| Small-cell carcinoma | 49/646 (7.6) | 15/44 (34.1) | 73/358 (20.4) | 137/1048 (13.1) | 28/276 (10.1) | 32/135 (23.7) | 99/520 (19.0) | 159/931 (17.1) |
| Carcinoid | 5/646 (0.8) | 0 | 1/358 (0.3) | 6/1048 (0.6) | 1/276 (0.4) | 1/135 (0.7) | 0 | 2/931 (0.2) |
The denominators represent only cancers with a known stage or known histologic type. The stage was not known in the case of 14 cancers after a positive screening test and 6 after no screening in the low-dose CT group and in the case of 4 cancers after a positive screening test, 2 after a negative screening test, and 6 after no screening in the radiography group. The histologic type was not known for 3 cancers after a positive screening test and 9 after no screening in the low-dose CT group and for 3 cancers after a positive screening test, 2 after a negative screening test, and 5 after no screening in the radiography group.
Negative screening tests included tests that revealed either minor or clinically significant abnormalities that were not suspicious for lung cancer.
The 892 lung cancers in participants with no screening test included 35 in participants who were never screened, 802 that were diagnosed during the post-screening period, and 55 in participants who were due for a screening test.
The 289 lung cancers in this category (in the two groups combined) included 28 adenosquamous carcinomas, 6 sarcomatoid carcinomas, 55 unclassified carcinomas, 1 anaplastic-type carcinoma, 1 carcinosarcoma, and 198 coded only as “non-small-cell carcinoma.”