Prognostic significance of histologic classification and tumor disappearance rate by computed tomography in lung cancer.

BACKGROUND

We investigated the prognostic value of the International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) classification and assessed the relationship between pathologic invasiveness and tumor disappearance rate (TDR) in lung adenocarcinoma with ground-glass opacity (GGO).

METHODS

We reviewed data from 202 consecutive patients operated on between 2000 and 2009 for clinical T1-2N0 lung adenocarcinoma with GGO and reclassified their histologic subtypes according to the IASLC/ATS/ERS classification. Thirty-nine patients had adenocarcinoma in situ (AIS), 29 minimally invasive adenocarcinoma (MIA), 75 lepidic predominant invasive adenocarcinoma (LPA), and 59 non-lepidic predominant invasive adenocarcinoma (NLPA). Survival outcomes were compared according to histologic subtype and TDR.

RESULTS

The mean age was 58 years and 101 patients (50%) were male. Lobectomy was performed in 161 patients (79.7%), wedge resection in 34 (16.8%), and segmentectomy in 7 (3.5%). Patients with AIS, MIA, and LPA had significantly smaller tumor sizes, earlier pathologic T stages, and lower incidences of lymphatic/pleural invasion than those with NLPA. The 5-year recurrence-free survival (RFS) rates were 95.1%, 94.5%, and 87.6% in the AIS + MIA, LPA, and NLPA groups, respectively (P=0.029). Tumors with a TDR>75% were associated with lepidic predominant histologic subtype and less pathologic invasiveness. The 5-year RFS rates were 97.4% in tumors with a TDR >75% and 87.8% in tumors with a TDR ≤75% (P=0.0009).

CONCLUSIONS

Histologic subtype according to the IASLC/ATS/ERS classification and TDR both correlated with pathologic invasiveness and predicted survival in patients with lung adenocarcinoma with GGO.