Cancer patients who kept smoking had a nearly doubled risk of either of those emergencies, as well as death from cardiovascular disease, new research showed.
“A cancer diagnosis is an extremely stressful life event, which often leads to significant changes in a person's lifestyle. Smoking, in particular, is a health-related behavior that can be heavily influenced by mental distress,” said study author Dr. Hyeok-Hee Lee, of Yonsei University College of Medicine in Seoul, South Korea.
For the study, published May 30 in the European Heart Journal, researchers analyzed data from a Korean national health claims database for more than 309,000 cancer survivors who had never had a heart attack or stroke. Participants had each answered questions about smoking and had health exams.
The research team split participants into groups based on their change in smoking habits after receiving a cancer diagnosis. Groups were sustained nonsmokers, quitters, initiators/relapsers and continuing smokers.
About 250,000 (80.9%) were sustained nonsmokers; just over 10% quit smoking; 1.5% initiated or relapsed to smoking, and 7.5% continued smoking after their cancer diagnosis.
Then the researchers assessed the risk of cardiovascular events for each group during a median of 5.5 years, adjusting for other characteristics that could influence these risks.
Compared with sustained nonsmoking, the risk of having a heart attack, stroke or cardiovascular-related death during follow-up was 86% among continuing smokers. It was 51% higher among initiators/relapsers and 20% higher among quitters. These findings were consistent for women and men.
Quitting smoking was associated with a 36% reduction in the risk of cardiovascular events compared with continued smoking, the study showed.
About 20% of patients who kept smoking cut back by at least 50% after being diagnosed with cancer. Still, they had the same risk of cardiovascular events as those who continued smoking with no reduction.
“Some individuals may find solace in successfully reducing their smoking without completely quitting,” Lee said in a journal news release. “However, our results imply that smoking less should not be the ultimate goal and that smokers should quit altogether to gain the benefits of kicking the habit entirely."
About 2% of nonsmokers started or resumed smoking after finding out they had cancer. This was associated with a 51% elevation in the risk of cardiovascular disease compared with sustained nonsmoking.
“Although our study does not provide conclusive evidence for the underlying causes of smoking initiation or relapse, some cancer survivors may lose motivation to have a healthy lifestyle after recovering, while others could turn to cigarettes as a way to cope with the stress of their diagnosis,” Lee said.
Further research is needed to determine why this happens, Lee said.
“Our results reinforce the existing evidence on the well-known cardiovascular risks of tobacco smoking and emphasize the benefits of smoking cessation, even for cancer survivors," Lee said. "Additionally, the finding that over 40% of patients who had been smoking before their cancer diagnosis continued to smoke afterwards highlights the need for more robust efforts to promote smoking cessation among cancer survivors, who already have an elevated risk of cardiovascular disease compared to their peers."
The American Heart Association has more on heart disease.
SOURCE: European Heart Journal, news release, May 30, 2023