Low diffusion capacity predicts poor prognosis in extensive stage small cell lung cancer: a single-center analysis of 10 years

Background Poor pulmonary function and chronic obstructive pulmonary disease (COPD) are associated with poorer overall survival (OS) in non-small-cell lung cancer (NSCLC) patients.

Few studies have investigated the association between pulmonary function and OS in small-cell lung cancer (SCLC) patients.

We compared the clinical characteristics of extensive disease SCLC (ED-SCLC) with or without moderately impaired diffusion capacity for carbon monoxide (DLco) and investigated the factors associated with survival in ED-SCLC patients.

Methods This retrospective single-center study was performed between January 2011 and December 2020.

Of the 307 SCLC patients who received cancer therapy during the study, 142 with ED-SCLC were analyzed.

The patients were divided into DLco < 60% group and DLco ≥ 60% groups.

OS and predictors of poor OS were analyzed.

Results The median OS of the 142 ED-SCLC patients was 9.3 months and the median age was 68 years.

In total, 129 (90.8%) patients had a history of smoking, and 60 (42.3%) had COPD.

Thirty-five (24.6%) patients were assigned to the DLco < 60% group.

Multivariate analysis revealed that DLco < 60% (odds ratio [OR], 1.609; 95% confidence interval [CI], 1.062–2.437; P = 0.025), number of metastases (OR, 1.488; 95% CI, 1.262–1.756; P < 0.001), and < 4 cycles of first-line chemotherapy (OR, 3.793; 95% CI, 2.530–5.686; P < 0.001) were associated with poor OS.

Forty (28.2%) patients received < 4 cycles of first-line chemotherapy; the most common reason for this was death (n = 22, 55%) from grade 4 febrile neutropenia (n = 15), infection (n = 5), or massive hemoptysis (n = 2).

The DLco < 60% group had a shorter median OS than the DLco ≥ 60% group (10.6 ± 0.8 vs. 4.9 ± 0.9 months, P = 0.003).

Conclusions In this study, approximately one quarter of the ED-SCLC patients had DLco < 60%.

Low DLco (but not forced expiratory volume in 1 s or forced vital capacity), a large number of metastases, and < 4 cycles of first-line chemotherapy were independent risk factors for poor survival outcomes in patients with ED-SCLC.