Smoking increases chances cancer will not have a good response to chemotherapy

When cancer patients are current smokers, their treatment is likely to be less effective and more expensive than if they quit smoking, a US study suggests.

The added cost largely stems from additional treatments needed after continuing smokers fail to respond to first-line cancer therapies, and totals roughly $11,000 per person, the study team calculates.

While smoking cessation after a cancer diagnosis has been found to improve survival odds, studies to date have not provided a clear picture of how treatment outcomes and costs are affected when smokers don’t quit, researchers note in JAMA Network Open.

“Chemicals from cigarette smoke affect virtually all cells in the body, including cancer cells,” said lead study author Dr. Graham Warren of the Medical University of South Carolina in Charleston.

“Smoking increases the chances that cancer will not have a good response to chemotherapy or radiotherapy, and increases the chance that cancer will have spread to a more advanced stage,” Warren said by email. “This increases the risk that standard cancer treatments will not be as effective, thus leading to an increased risk of recurrence.”

About one in five cancer patients are current smokers, the researchers estimate based on data from a 2014 U.S. Surgeon General report. Building on this report, they created a model to calculate the added cost of treating smokers.

They assumed 30 percent of nonsmokers fail to respond to initial treatment and that 20 percent of cancer patients are current smokers. Based on past research, they also assumed that smokers are 60 percent more likely than nonsmokers to fail to respond to initial treatment.

In addition, researchers assumed an average added cost of $100,000 for treating every patient who fails to respond to initial treatments.

With this model, the study team calculated that the additional incremental cost of treating every 1,000 patients would be $2.1 million, reflecting an extra cost of $10,678 for every smoking patient.

Across 1.6 million patients diagnosed with cancer in the U.S. each year, this would add up to potential added annual costs of $3.4 billion, the study team concludes.

One limitation of the analysis is the lack of specific cost estimates for so-called second-line treatments, which are the options that doctors try when patients don’t respond to initial treatment regimens, the study authors note.

Cost estimates in the analysis also don’t include many expenses related to smoking, including mortality from other causes, toxic effects of cancer treatment and the risk of developing multiple types of cancer, the researchers also point out.

The researchers also didn’t calculate how costs might be affected if smoking cessation therapy was a standard part of care for smokers diagnosed with cancer.

Still, the results should give smokers with cancer yet another reason to quit, said Cara Petrucci, co-author of an accompanying editorial and a researcher at the Roswell Park Comprehensive Cancer Center in Buffalo, New York.

“Something as simple as helping cancer patients quit smoking can result in better clinical outcomes for the patient but also save billions of dollars in healthcare costs,” Petrucci said by email. “Every cancer care facility should be screening every patient for tobacco use and offering every available means to help those patients quit smoking as soon as possible.”