Radiological and pathological analysis of LDCT screen detected and surgically resected sub-centimetre lung nodules in 44 asymptomatic patients.

PURPOSE: Once lung cancer is detected due to clinical symptoms or by being visible on chest X-ray, it is usually high stage and non-operable. In order to improve mortality rates in lung cancer, low-dose CT (LDCT) screening of "high risk" individuals is gaining popularity. However, the rate of malignancy in LDCT detected sub-centimetre lung nodules is not clear. We aimed to analyze surgically resected specimens in this patient group to explore cost effectiveness and recommendations for clinical management of these nodules.

MATERIAL & METHODS: Our hospital pathology database was searched for sub-centimeter lung nodules detected by LDCT screening which were resected. The patient demographics were collected and the radiologic and pathologic characteristics of those nodules were analyzed.

RESULTS: From the records, 44 patients with 46 resected subcentimetre nodules were identified. Patients were selected for surgery based on an irregular shape, growth in size during follow up, family history of lung cancer or personal history of cancer of other sites, previous lung disease, smoking and personal anxiety. Of the 44 patients, 33 were women and the ages ranged from 43 to 76 years (56.75 ± 8.44). All nodules were equal to, or less than 10 mm with a mean diameter of 7.81 ± 1.80 mm (SD). Out of 46 nodules, the pathological diagnoses were: invasive adenocarcinoma (ACa) in 4 (8.7%); adenocarcinoma in situ (AIS) or atypical adenomatous hyperplasia (AAH) in 29 (63%); benign fibrosis/fibrotic scar with inflammation or calcification in 12 (26.1%); an intrapulmonary benign lymph node in 1 (2.2%). Of the ACa, AIS and AAH groups (a total of 31 patients), 77% were women (24 vs. 7). The cancer or pre-cancer nodules (ACa, AIS and AAH) tended to be larger than benign fibrotic scars (P = 0.039). Amongst all characteristics, significant statistical differences were found when the following radiological features were considered: reconstructed nodule shape (P = 0.011), margin (P = 0.003) and ground glass pattern (P = 0.000). The patient's age, the axial morphology of the lesion, relationship to major vessels or visceral pleura and location within the lung parenchyma were not predictive of the pathologic diagnosis. Only one of the 31 patients with a cancer or pre-cancer nodule was a smoker.

CONCLUSION: ACa, AIS and AAH nodules detected on LDCT included more women (77%) than men in our cohort. Smoking as inclusive criteria for LDCT screening of lung cancer needs to be further evaluated in the Chinese population. The reconstructed nodule shape, density and margin may help radiologists to identify small cancer and pre-cancer nodules from benign conditions.