Top Takeaways from ASCO: Lung cancer

Issue: December 10, 2015

CHICAGO — Physical activity may reduce lung cancer incidence among postmenopausal women, according to study results presented at the ASCO Annual Meeting.

It also may reduce lung cancer-related mortality among those who are diagnosed with the disease, results showed.

“Our study suggests an association between physical activity and reduced lung cancer incidence and mortality,” Ange Wang, study investigator and MD candidate at Stanford University School of Medicine, told Healio.com. “Together with past studies, this suggests that physical activity may be protective in these instances and is unlikely to be harmful.”

Wang and Heather Wakelee, MD, a medical oncologist and associate professor of medicine (oncology) at Stanford University Medical Center who also served as a study investigator, discussed the findings and potential impact of the results with Healio.com.

Heather Wakelee

Lung cancer incidence, mortality

Wang and colleagues assessed the relationship between physical activity and lung cancer in a prospective cohort of 134,058 postmenopausal women. Data were collected from the Women’s Health Initiative (WHI) observational study and clinical trial. The WHI study enrolled women aged 50-79 years at 40 U.S. clinical centers between 1993 and 1998.

Cox proportional hazard models were used to assess the link between lung cancer incidence and mortality and physical activity at baseline, as well as sedentary behavior (sitting time per day). Activity levels among participants were classified as inactive (< 100 metabolic equivalent of task [MET] minutes/week), which served as the reference point; low (100 to < 500 MET minutes/week); medium (500 to < 1,200 MET minutes/week); or high (≥ 1,200 MET minutes/week). MET minutes per week takes into account both the duration and intensity of exercise, Wang said.

Ange Wang

During the mean follow-up period of 11.8 years, 2,229 cases of incident lung cancer and 1,427 deaths from lung cancer were identified. Higher total levels of physical activity at baseline correlated with reductions in both lung cancer incidence [P = .004; physical activity levels: low (HR = 0.86; 95% CI, 0.77-0.96), medium (HR = 0.81; 95% CI, 0.72-0.91), high (HR = 0.89; 95% CI, 0.78-1.01)] and mortality [P < .0001; physical activity levels: low (HR = 0.8; 95% CI, 0.7-0.92), medium (HR = 0.68; 95% CI, 0.58-0.79), high (HR = 0.77; 95% CI, 0.65-0.91)].

The researchers also examined the impact of BMI and smoking status. BMI was determined to be an effect modifier of the link between total physical activity and lung cancer incidence (P = .008); reduced HRs were found for rising activity levels in patients with a BMI greater than 30. Smoking status was not found to be an effect modifier, but former smokers (> 10 pack-years) and current smokers were estimated to have lower lung cancer incidence and mortality HRs for increasing physical activity levels compared with inactive women of the same smoking status.

Wang and colleagues also performed a subtype analysis, which demonstrated that reduced lung cancer mortality correlated with heightened total physical activity levels for both overall non–small cell lung cancer and adenocarcinoma.

Need for further research

Wang and Wakelee both note that additional studies are needed to determine the causal link between incidence and mortality rates of lung cancer and physical activity.

“Overall, this suggests that increased physical activity levels are associated with decreases in incidence and mortality from lung cancer, but as a prospective cohort study, we cannot say anything about the causality. Women who have better lung health prior to diagnosis may be more likely to participate in physical activity, which may be a confounder,” Wang told Healio.com. “The results warrant further investigation in [a randomized controlled trial] format.”

Further research will also help to determine if recommending physical activity prior to or after physical activity “is truly protective,” according to Wang.

According to Wakelee, patients with lung cancer are encouraged to maintain physical activity after their diagnosis, and their study “provides further support for that recommendation.” – by Julia Ernst, MS

Reference:

Wang A, et al. Abstract 1519. Presented at: ASCO Annual Meeting; May 29-June 2, 2015; Chicago.

Disclosure: Wang reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.