Abstract

Background

Lower treatment rates in older lung cancer patients does not necessarily imply under-treatment due to contraindications from higher levels of advanced disease, comorbidities, and frailty.

Aim: This study aims to quantify how much of the lower survival in older patients in Northern Ireland is mediated through lower treatment rates, adjusting for clinical and demographic factors.

Method

For lung cancer patients diagnosed between 2012-2015, hospital episode, multidisciplinary team meeting, and Northern Ireland Cancer Registry (NICR) information was linked. Age was categorised into young (<74) and old (≥75), and treatment was defined as surgery, chemotherapy, radiotherapy or no treatment. A mediation methodology using the g-computation formula¹ was used to estimate 1) the natural indirect effect (NIE) of age on 2-year observed survival mediated through treatment and 2) the natural direct effect (NDE) of age on survival not mediated through treatment. The analysis accounted for stage, comorbidities, performance status (ECOG) and lung function (FEV1/FVC ratio).

Results

A total of 4,233 patients were included in the analysis (1,755 were 75 and over); elderly patients were approximately 80%, 42% and 86% (p<0.001) less likely to undergo surgery, radiotherapy and chemotherapy, respectively. The Total Causal Effect (TCE) of older age (i.e. NIE + NDE) on survival was 14.6% (95% confidence interval [CI], 0.11—0.18, P<0.001) reduction, split between the NIE (6.4%; 95% CI 0.03—0.13, P<0.001), and the NDE (8.2%; 95% CI 0.03—0.10, P=0.001).

Conclusion

Roughly 43% of the survival difference between younger and older lung cancer patients may be due to older cancer patients experiencing lower treatment rates for the same levels of disease stage, comorbidity, pulmonary function, and performance status. This study highlights the potential of offering more treatment to older lung cancer patients, and the need for comprehensive geriatric assessment in these patients with diverse health issues and outcomes.