A survey carried out at the Seattle Cancer Care Alliance discovered that 21 percent of their patients use cannabis to help deal with symptoms of cancer. And a quarter of those users believe it helps treat the cancer itself – despite lack of scientific evidence. Steven Pargam, Principal Investigator at Fred Hutchinson Cancer Research Center, tells us about the motivation for the survey, and how it might impact patients (and healthcare practitioners) in the future.

What inspired you to study cannabis use?

We were motivated to conduct this research by our patients. Increasing numbers of patients were using cannabis, and we were being asked about the safety of various forms. When we looked at prior research it was very limited – there were only a few small studies that assessed the prevalence of cannabis use among cancer patients, and there was not much data on safety and efficacy. To answer many of our patients’ questions and to help provide guidance to our colleagues, we felt we needed to first understand the frequency, methods and reasons for cannabis use during treatment.

Were you surprised by the results?

We expected that cancer patients would report using cannabis for nausea or as an appetite stimulant, as these symptoms are where it is most frequently purported to provide benefits. So it was interesting that patients reported using cannabis for symptoms such as dealing with stress, coping with their illness and depression. And despite a lack of scientific evidence, more than a quarter of cannabis-using patients actually thought it was helping to treat their cancer. We were also surprised that patients, regardless of whether they had used cannabis or not, were interested in learning more. Add to this that only about 15 percent of survey respondents got information about cannabis from their cancer team, and we see a real need to better educate both patients and providers.

What analytical methods did you use to validate your survey?

We performed urinalysis using an enzyme multiplied immunoassay to detect THC – commonly used in clinical practice as a screening test for cannabis use. Samples were considered positive if they had THC concentrations ≥50 ng/mL. Samples that were positive but didn’t meet the level of detection of the assay (<50 ng/ml), were sent to an outside reference laboratory for confirmatory testing using GC-MS, which has greater sensitivity.

Tell us about your research team…

A number of colleagues and experts have lent their expertise. Our team is multi-disciplinary, and members range from substance abuse experts and epidemiologists, to infectious diseases, oncology and pulmonary specialists. Cancer care providers, patients and caregivers helped us modify the survey. No doubt with the diversity of ideas and areas of study, the work we can accomplish will have more impact.

How would you like to build on this initial research?

We would like to complete additional surveys at other centers or have others attempt to replicate our findings, because we don’t know if these data reflect national trends or a snapshot in a community where recreational cannabis is more readily available. I am particularly interested in looking at specific sub-groups of patients in more detail. Future studies that focus on cancer providers perceptions of cannabis use among their patients are also important. Eventually, we hope to see more rigorous clinical trials aimed at addressing the potential risks and benefits of cannabis in cancer care. The more data we have the better we will be able to educate and protect our patients.