Impact of Clinical Trial Participation on Survival of Patients with Metastatic Non-Small Cell Lung Cancer

The impact of clinical trial participation on overall survival is unclear. We hypothesized that enrollment in a therapeutic drug clinical trial is associated with longer overall survival in patients with metastatic non-small cell lung cancer (NSCLC).

We linked electronic medical record and Washington State cancer registry data to identify patients with metastatic NSCLC diagnosed between January 1, 2007, and December 31, 2015 who received treatment at a National Cancer Institute-designated cancer center. The exposure was trial enrollment. The primary outcome was overall survival, defined as the date of second-line treatment initiation to date of death or last follow-up. We used a conditional landmark analysis starting at the date of second-line treatment initiation and propensity scores with inverse probability of treatment weighting to estimate the association between trial enrollment and survival.

Of 215 patients, 40 (19%) participated in a second-line trial. Trial participants were more likely to be never smokers (45% vs 27%), have a good performance status (88% vs 77%) and have EGFR (48% vs 14%) and ALK mutations (8% vs 5%) than nonparticipants. Trial participants had similar overall survival to nonparticipants (HR 1.05; 95% CI, 0.72, 1.53; p = 0.81) after adjusting for sociodemographic and disease characteristics.

Accounting for the immortal time bias and selection bias, trial participation does not appear detrimental to survival. This finding may be reassuring to patients and supports programs and policies to improve clinical trial access.