Does Cardiorespiratory Fitness Affect Lung Cancer Risk Among Male Smokers?

Among former male smokers, higher cardiorespiratory fitness (CRF) is independently linked to a lower risk for lung cancer incidence. Moreover, among current male smokers who have been diagnosed with lung cancer, higher CRF is independently associated with a reduced risk for morality from cancer and a longer survival time. Researchers conducted a prospective follow-up study on the subject among male veterans, with the results published in the American Journal of Preventive Medicine.

The investigators sought to assess the association between CRF and the incidence of lung cancer, as well as between CRF and cancer mortality, among both former and current male smokers. Between 1987 and 2014, researchers evaluated CRF, which they quantified from treadmill exercise testing, in a total of 2979 male veterans, 1602 of whom were former smokers and 1377 of whom were current smokers. The mean participant age was 59.1±17.4 years. The researchers followed the men for a mean 11.6±7 years. The researchers used multivariable Cox hazard models and population-attributable fraction of low CRF (<5 metabolic equivalents [METs]) for cancer outcomes during 2018.

Of 99 case patients who were diagnosed with lung cancer, 79 died of cancer 3.6±4.6 years after diagnosis. Among the former male smokers, both continuous and categoric models demonstrated independent and inverse relationships between CRF and incidence of cancer. Each 1-MET higher CRF was associated with a 13% reduction in the risk for incidence of lung cancer (P =.016). In fact, those participants with moderate and high CRF exhibited 51% and 77% (P_trend =.015) reductions, respectively, in the risk for incidence of lung cancer compared with those participants with low CRF.

In addition, among current smokers who were later diagnosed with lung cancer, higher CRF was associated with a lower risk for mortality from cancer and longer survival time. According to a continuous model, each 1-MET higher CRF was associated with an 18% reduction in the risk for mortality from cancer (P =.008). In a categoric model, moderate and high CRF were linked to 84% and 85% (P_trend <.001) reductions, respectively, in risk for cancer mortality.

Furthermore, the population-attributable fraction for incidence of lung cancer was 10.8% among former male smokers and 22.3% for mortality from cancer among current smokers.

The investigators concluded that according to the findings from this study, screening for low CRF and attaining at least moderate CRF might potentially reduce rates of morbidity and mortality from lung cancer, thus offering a preventive strategy for smokers. Additional prospective studies on this topic are warranted.

Reference

Vainshelboim B, Lima RM, Kokkinos P, Myers J. Cardiorespiratory fitness, lung cancer incidence, and cancer mortality in male smokers. Am J Prev Med. 2019;57(5):659-666.