Smoking Linked With Worse Pancreatic Cancer Survival

Cigarette smoking was associated with a nearly 40% reduction in survival among patients with pancreatic cancer, according to the results of a recent study. Current smokers had an increased risk for death compared with never smokers, the study showed.

“Reduced survival was also observed for patients with high levels of plasma cotinine, the major circulating metabolite of nicotine,” wrote Brian M. Wolpin, MD, MPH, of the Dana-Farber Cancer Institute in Boston, and colleagues in the Journal of Clinical Oncology. “In contrast, no reduction in survival was identified for former smokers, suggesting a potential benefit to smoking cessation and an opportunity to improve survival for patients with pancreatic cancer.”

Previous research has established cigarette smoking as a risk factor for pancreatic cancer, and it is estimated that it may contribute to one in five cases of the disease. With this study, Wolpin and colleagues wanted to prospectively evaluate the association of smoking with pancreatic cancer survival.

They analyzed data on smoking status from 1,037 patients from two large US prospective cohort studies. Patients were diagnosed between 1986 and 2013. They also evaluated survival by prediagnostic circulating levels of cotinine among 485 patients from four prospective US cohorts. On the basis of these prediagnostic cotinine levels, they classified patients as nonsmokers, light smokers, or heavy smokers.

Current smokers had a 37% increased risk for death compared with never smokers according to a multivariable-adjusted analysis (P = .003).

“We considered whether current smoking may predominantly impact survival among patients who undergo surgery because of a potential increase in perioperative mortality,” the researchers wrote. “However, after excluding patients with localized disease, our results were not materially altered.”

In addition, risk for death among current smokers was not significantly altered when the data were adjusted for body mass index, diabetes, or other comorbid illness.

The researchers also observed a negative trend in survival for increasing pack-years of smoking, with a hazard ratio (HR) for death of 1.49 for more than 60 pack-years of smoking compared with never smoking. The median survival for nonsmokers was 5 months, compared with 3 months for current smokers with more than a 60 pack-year smoking history.

The survival analysis showed that survival among former smokers was similar to that of never smokers regardless of the time since quitting.

Heavy smokers, defined as those having cotinine levels of 21 ng/mL or greater, had an HR for death of 1.76 compared with nonsmokers. Among patients with cotinine levels measured within 5 years of diagnosis, heavy smokers had more than twice the risk for death compared with nonsmokers (HR, 2.47).

The researchers acknowledged that one weakness of their study was the use of overall mortality instead of pancreatic cancer–specific mortality. However, they noted that less than “5% of patients with pancreatic cancer are cured of their disease, such that overall mortality is a good surrogate for cancer-specific mortality.”