WITH THE LEGALIZATION OF MEDICAL CANNABIS in 36 states and the District of Columbia, people with cancer are asking about taking it to manage side effects of the disease and its treatment. Here are some practical questions you can ask when considering cannabis.

What are the rules in your state?
Cannabis laws vary by state, so patients should see where their state stands. Patients will also need to check on local regulations while traveling, says Prasanna Ananth, a pediatric hematologist-oncologist at Yale School of Medicine in New Haven, Connecticut. She gives the example of a patient who uses medical cannabis and may travel out of state to see a specialist. By crossing state lines, they may find themselves violating a different set of rules.

Where are you getting cannabis?
“You need to make sure you are getting this if you are using it from a dispensary that is licensed, regulated and controlled,” says Brooke Worster, a pain management and palliative medicine physician at Sidney Kimmel Cancer Center–Jefferson Health in Philadelphia. She recommends against acquiring a vaping device from a neighbor or ordering cannabis from an unknown source on the internet.

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But Ananth cautions patients to be aware that just because cannabis is being sold at a state dispensary, it does not mean it has been thoroughly tested for contaminants or quality. She says that some states have more regulations than others, such as requiring dispensaries to be staffed by board-certified pharmacists, but even this does not ensure quality. “While dispensaries may give the impression of greater safety or cleanliness, it’s not a guarantee,” she says.

What form of cannabis will work best for you?
A study published in the June 2021 issue of Cancer Communications found that oncologists tend to prefer oral formulations for their patients. Around 15% of 233 oncologists surveyed said they did not support medical cannabis use in patients. Of the remaining doctors who were open to cannabis use, around 50% said they supported oral cannabis, 18% supported vaping and 10% supported smoking.

“I suspect that health care professionals are more comfortable recommending an oral route of use because that is how the vast majority of pharmaceuticals are administered,” says Ilana Braun, a psychiatrist and chief of the Division of Adult Psychosocial Oncology at the Dana-Farber Cancer Institute in Boston, who co-authored the study. However, Braun warns that patients using oral cannabis products should know that they will take longer to have a therapeutic effect than inhaled cannabis. “On occasion, this may lead patients to take too much cannabis thinking that it wasn’t working,” she says.

Some oncologists discourage patients from using inhaled products due to concerns about lung health, but others speak more favorably of inhaled cannabis. Donald Abrams, an oncologist at the University of California, San Francisco, Osher Center for Integrative Medicine notes that inhalation gives patients greater control over onset, depth and duration of the effects of cannabis compared to oral ingestion of a product. Tinctures—concentrated herbal extracts, often delivered as oils under the tongue—can offer a middle ground, providing a somewhat faster effect than edible products while allowing for less frequent dosing than inhaled products, he says.

What is your budget?
Getting certified and renewing medical cannabis certifications can cost hundreds of dollars. Cannabis is not covered by health insurance, and costs can add up, says Abigail Johnston, who uses cannabis to treat symptoms of her metastatic breast cancer and its treatment. She estimates that her cannabis oils cost nearly $200 per month. She also notes that she has to pay in cash for her cannabis, since financial institutions often will not do business with the cannabis industry due to the illegality of cannabis according to federal law.

What does your employer think?
Employers will vary in their tolerance for medical cannabis use. Worster recommends that patients have a conversation with human resources or occupational health to determine their employer’s stance.

Will you need to operate vehicles or other potentially dangerous machinery?
Worster tells patients to pay attention to driving and cannabis use, much as they would pay attention to alcohol and driving. “It can impair you. You need to assess how you feel and what you’re using,” she says, adding that driving after using a product with a high concentration of THC can bring risks. She also says that cannabis use can prevent people from getting gun licenses.

Do you have particular risk factors?
Doctors emphasize that people with cancer should always tell their doctor about their cannabis use. The doctor may have information specific to them or be able to spot adverse events. Steven Pergam, an infectious disease specialist at the Fred Hutchinson Cancer Research Center and the Seattle Cancer Care Alliance (SCCA), warns that people with very weakened immune systems, such as transplant recipients or patients with severe leukemia, could be at risk from mold infections from cannabis, particularly from inhaled forms.

Cannabis may also interact with other medications a person is taking by intensifying or blunting a medication’s effects. Data presented at the 2020 Virtual European Society for Molecular Oncology Congress described study results for 102 patients in Israel with advanced cancers taking immune checkpoint inhibitors. The study found an association between cannabis use and reduced survival. However, Abrams notes that the patients using cannabis were more likely to be getting immunotherapy as their second or third treatment as opposed to their first treatment, which could explain their reduced survival.

Components of cannabis are processed by an enzyme in the liver that also processes many medications used by people with cancer, Abrams adds. Using large quantities of cannabis could slow down the liver’s ability to process certain other drugs, such as the blood-thinner warfarin, leading to higher concentrations of the drugs than intended in patients.

What will you do if you are hospitalized?
Many hospitals, particularly federally funded hospitals, do not allow cannabis on the premises, says Ananth. People with cancer using cannabis need to be aware that they may need to switch to other methods of symptom relief if hospitalized.

How flexible are you?
Worster says one of the biggest practical challenges her patients face is maintaining consistent access to a product they like. “The marketplace is just not mature enough, and it’s a plant,” she says. “Someone will say to me, ‘Oh my gosh, I got this. This was the product, and it was really, really helpful. And then I went back to that same dispensary and they didn’t have it.’”

Ananth says another variable is that different people respond differently to the same products. “You can sort of judge, but everyone is different, and that’s where the research really lags,” she says. “Just because one edible has this effect on one individual doesn’t mean it’s going to be the same for someone else.”

Kate Yandell is a writer and editor and was formerly the digital editor of Cancer Today.