Trials don't ask cancer subjects about tobacco use
Tobacco can hamper cancer treatments
Despite evidence suggesting that tobacco use can hamper cancer treatments, patients with cancer who enter clinical trials are rarely asked about their use of tobacco, according to a recent study.
The study, published in the Journal of Clinical Oncology1, looked at more than 150 national cooperative-group trials that were actively enrolling participants. Investigators found that less than a third of the trials assessed any form of tobacco use when subjects enrolled, and less than 5% asked about tobacco use during follow-up visits. None of the trials provided cessation support for participants who wanted to quit using tobacco.
Graham Warren, MD, PhD, assistant professor in the department of radiation medicine at Roswell Park Cancer Institute in Buffalo, NY, says these findings are significant because of research that shows tobacco use can erode the effectiveness of cancer treatments, decrease survival, increase risk of recurrence and increase the risk of mortality from heart disease, stroke and pulmonary disease.
"If tobacco decreases the effectiveness of chemotherapy, biologic therapy, radiation therapy or if it increases the risk of recurrence after surgery, then tobacco can alter the treatment outcomes used in clinical trials," Warren says.
Measuring the magnitude
Warren says that while many people understand that tobacco use can increase the risk of developing cancer, its role in decreasing the effectiveness of cancer treatment is less well known.
Failing to assess tobacco use in subjects means that clinical trials will be unable to measure the magnitude of these effects, Warren says. At the same time, it poses potential risks to the subjects themselves.
"If you're looking at risk from toxicity of treatment, there are several studies that show that toxicity of treatment is elevated by tobacco," he says. "If you're looking at risk of recurrence, then yes, the risk of recurrence is increased with the use of tobacco. If you're interested in the risk of heart disease or pulmonary problems or wound infections or pneumonia, tobacco use increases the risk for those as well.
"I think the biggest conclusion is yes, these are all risks," Warren says. "In reality, many of these things probably occur and are amplified by tobacco, but unfortunately right now, we have no randomized data that has looked at it well."
He says the first step toward changing that is for researchers to agree on guidelines to measure tobacco use — past use, current use and any use of tobacco cessation products. Asking those questions of participants would provide important data about how tobacco use can affect outcomes.
"I think that assessment not only at diagnosis but also during follow-up is an important parameter to try and include in clinical trials design," Warren says.
Warren says there is interest in developing these questions and in providing a formal structure for assessing tobacco use in clinical trials.
In the meantime, Warren says, IRBs should consider this issue when reviewing cancer treatment protocols, asking whether a past or current use of tobacco has been considered in the design of the trial.
"We know that about 30% of cancer patients use tobacco at time of diagnosis," he says. "That means there is a reasonably substantial portion of the population who is at risk for tobacco use and could therefore be at risk for having changes in treatment response, diagnosis and outcomes that most clinical trials look at."
He believes that informed consent documents should also address this issue.
"I believe that there should be an awareness of the fact that tobacco can increase the risk of treatment failure, toxicity, as well as decreased overall health," Warren says. "It should be something that patients should be made aware of because there is a good likelihood that continued tobacco use will substantially alter their long-term outcomes whether they're related to the clinical trial or not."
And Warren says IRBs should ask investigators in clinical trials whether they plan to offer tobacco cessation programs for participants who currently use tobacco. He believes that cancer patients — including trial participants — should be offered tobacco cessation support as a standard of care.
"A lot of times, clinical trials may or may not benefit the patient, but this is one area where tobacco cessation would benefit the patient directly," Warren says. "It's not a theoretical benefit — it would be something that would improve the health of the patient."
- Peters EN, Torres E, Toll BA, Warren GW et al. Tobacco assessment in actively accruing national cancer institute cooperative group program clinical trials. J Clin Oncol 2012 Aug 10;30(23):2869-75.