A population-based analysis of outcomes after radiotherapy in intensive care unit patients with lung cancer.

Background: As the value of radiotherapy (RT) in intensive care unit (ICU) patients with lung cancer is of uncertain efficacy, we evaluated characteristics, outcomes and RT utilization for such patients in Ontario, Canada.

Methods: Multiple administrative databases were linked deterministically using unique encoded identifiers to identify eligible patients between April 1, 2007, and March 31, 2014. Differences in patient, treatment, institution and tumor characteristics between RT and non-RT groups at the level of episode of care were compared. Overall survival (OS) was evaluated using the Kaplan-Meier method, with differences compared using the log-rank test. Univariable and multivariable Cox proportional hazard modeling were performed to assess the effect of RT on survival.

Results: RT was delivered in 133 episodes of care to 1.0% (n=131) of the 13,739 unique patients with lung cancer. RT delivery was associated with younger age (median 65 68, P<0.001), ventilation (79.8% 38.2%, P<0.001) and longer ventilation duration (median 6 0 days, P<0.001). Pre-ICU disposition via transfer (35.3% 9.7%) or the emergency room (ER) (28.6% 21.9%) was more likely in the RT group (P<0.001). RT delivery varied, with half of the regions treating ≤5 patients each. ICU discharge was common in both RT (n=75, 56.4%) and non-RT (n=10,405, 71.4%) cohorts. One-year OS was poor in both groups, but most notably in the RT group (11.3% 42.4%). RT was associated with inferior 1-year OS on unadjusted modeling (HR =1.99, P<0.001), with ventilation and pre-ICU disposition adjusting this finding towards the null on multivariable modeling (HR =1.17, P=0.095).

Conclusions: Major geographic disparities exist in the rare use of RT for lung cancer in the ICU. A significant proportion of patients receiving RT achieve discharge and a minority achieve prolonged survival, suggesting that RT use may not be futile.