A retrospective study of volume doubling time in surgically resected non-small cell lung cancer

Abstract

Background and objective: Volume doubling time (VDT) contributes to the evaluation of the indeterminate pulmonary nodule, an increasingly frequent problem given the rising use of computed tomography (CT). We aimed to correlate patient and tumour characteristics with VDT and growth rates of primary non-small cell lung cancers (NSCLC).

Methods: Surgically treated NSCLC, which underwent two or more CT scans separated by 25 or more days were studied. Tumour volume was measured using semi-automated volumetric software. VDT and growth rate (1/VDT) were correlated with patient and tumour characteristics.

Results: Thirty-six adenocarcinomas (AC), six squamous cell carcinoma (SCC), two large cell and two carcinoids in 46 patients had 109 eligible scans. Median VDT was 191 days (range -9435 to 2256 days); median growth rate was 0.0038 (range -0.0086 to 0.0186). Median growth rate of AC was significantly slower than SCC (0.0034 vs. 0.0103, P = 0.037). Nine AC had VDT >400 days, three of which developed distant metastases. Median growth rate of AC was faster in smokers compared with never-smokers (0.0052 vs. 0.0014, P = 0.02). Growth rate was not related to symptoms at diagnosis (P = 0.16). Less differentiated tumours tended to grow faster than more differentiated (P = 0.0038). Growth curves of 12 multi-imaged tumours conformed best with the exponential model of growth.

Conclusions: NSCLC growth rate appears to be highly variable and related to histological subtype and smoking history, but not the presence of symptoms at diagnosis. Significant growth may be detected in as little as 2 months in NSCLC in smokers. Relatively slow-growing AC can metastasize.

Keywords: adenocarcinoma; lung neoplasm; non-small cell lung cancer; time factor; tomography.