Many people with colon cancer or lung cancer continue to smoke after being diagnosed, researchers say. They emphasize the need for cancer specialists to recommend that people quit and give them help to do so.

The findings of the study in Monday's issue of the journal Cancer describe how some people with cancer might need more help to quit smoking after their diagnosis.

Delivering smoking cessation treatment soon after a cancer diagnosis seems to increase the likelihood of staying smoke-free. (iStock)

That's important because continuing to smoke can harm a patients' response to treatment and potentially even survival, said study leader Elyse Park of the Massachusetts General Hospital and Harvard Medical School in Boston.

"These findings can help cancer clinicians identify patients who are at risk for smoking and guide tobacco counseling" for cancer patients, said Park.

Park and her co-authors reviewed smoking rates of 5,338 lung and colorectal cancer patients in the U.S.

At diagnosis, 39 per cent of lung cancer patients and 14 per cent of colorectal cancer patients were smoking.

After five months, 14 per cent of lung cancer patients and 9 per cent of colorectal cancer patients were still smoking.

The participants reported whether they smoked or not themselves, which probably means it was underestimated, the researchers said.

Preventing relapse

"Our findings emphasize the importance of following …recommendations and starting smoking-cessation and relapse prevention conversations when a cancer patient presents with a suspected malignancy, regardless of whether or not it is an established smoking-related cancer," the study's authors said.

"This is a critical time to address tobacco treatment, because research indicates that the closer to the time of diagnosis smoking cessation treatment is delivered, the greater the likelihood of continued abstinence post-treatment."

Those with lung and colorectal cancer who continued to smoke after diagnosis had certain characteristics. For example, they tended to smoke more cigarettes a day and did not have surgery.

"Oncologists should be able to routinely advise their patients to quit and not relapse — with personalization of the message," Dr. Carolyn Dresler said in a journal editorial accompanying the study.

The findings emphasize that it is never too late to quit, Dresler said.

"We know enough now to implement effective cessation programs to identify and help cancer patients quit at the time of diagnosis and support them to prevent relapse. By doing so, we maximize patients' response to therapy, their quality of life, and their longevity," she concluded.