Side effects—thought to be dose- or patient age- related—can be both physiologic (hypotension with reflex tachycardia, gastroparesis, ataxia, somnolence, dry mouth), and psychologic (euphoria, poor concentration), and, at high doses, anxiety, delusions, and hallucinations.
Based on anecdotal reports, tolerance for many of these effects develops over 1 to 2 weeks.9
Although many cellular and molecular studies provide strong evidence that inhaled marijuana is carcinogenic, the epidemiologic evidence of a link between marijuana use and cancer is still inconclusive.3
It’s not surprising, then, that significant concerns remain about recommending cannabis among practitioners:
“My biggest concerns with medical marijuana is that because of the lack of studies, we do not know if there are significant contraindications that might influence oncology treatment and potential drug-drug interactions that should be considered,” according to Arlene Cramer FNP, AHPCN, from UC San Diego’s Doris A Howell Palliative Care Service.
In addition, she continued, “Medical marijuana is expensive. Obtaining the prescription and medical marijuana care are out-of-pocket expenses, as is the actual purchase of the marijuana. Cost is a major obstacle to our poorer clients, and I fear that they may resort to illegal and less safe sources to purchase these products.”
Managing Side Effects With Marijuana
What is known at this point is that cancer-related cannabinoids are used with some effectiveness as an adjuvant pain management strategy, as an antinausea/vomiting agent for patients undergoing chemotherapy, and as an appetite stimulant to offset cancer-related weight loss. In addition, providers see anecdotal benefits when patients use cannabis as a sleep aid and to reduce anxiety.3,5,10
In 2015, the Journal of the American Medical Association published a meta-analysis of 79 randomized trials covering more than 6400 participants, finding moderate-quality evidence to support the use of cannabinoids for treating chronic pain. Additional analyses concluded that some low-quality evidence exists suggesting that cannabinoids could impact nausea and vomiting due to chemotherapy, weight gain in HIV infection, sleep disorders, and Tourette syndrome.11
It is suggested that cannabinoids may act synergistically with opioid analgesics in managing cancer-related pain. In the treatment of HIV-related peripheral neuropathy, data show that cannabinoids may be effective in the treatment of neuropathic symptoms that patients experience due to disease, chemotherapies, and diabetes-associated comorbidities.8,12
As an antiemetic cannabinoid agent, dronabinol and nabilone are FDA-approved for the treatment of nausea and vomiting associated with cancer chemotherapy in patients who have failed to respond to conventional antiemetics. The FDA approved a new oral solution formulation of dronabinol (Syndros) in July for the treatment of chemotherapy-induced nausea and vomiting (CINV) in patients who have not responded to conventional antiemetic therapies.
However, cannabinoids for this use may prompt potent side effects (ie, anxiety, paranoia, agitation) and may only be effective for a short time.4,13
And for most patients, 5-HT3 receptor antagonists and NK-1 receptor antagonist agents—now prescribed as standard therapies—have been shown to be effective and well tolerated to treat CINV, thus lessening the urgency to study cannabinoid as an antiemetic agent.2
|TS, a 50-year-old female patient, is receiving ongoing care from medical oncology and palliative care teams for metastatic colorectal cancer (pT4zN1bM1 with positive margins). The patient was first diagnosed in January 2014 and presented with abdominal pain. Treatment included colostomy, 4 cycles of FOLFOX, liver resection, and bilateral ureteral stent placement. The patient currently has stable disease and is being treated with FOLFIRI every 2 weeks. Most recent issues:
• Urinary tract infection, treated with macrobid, pyridium
• Cancer-related pain/neuropathic pain, radiating from abdomen to back, treated with fentanyl patch (100 mcg/hour, changed every 72 hours), hydromorphone (8-12 mg/day), and acetaminophen (as needed).
• Refractory nausea: better symptom control now, treated with olanzapine and cannabis (edible).
TS reports that cannabis has reduced her nausea related to chemotherapy and increased her appetite so that she “feels better” since starting cannabis 2 months ago, and her weight gain = 2 lbs: “I was reluctant to use (cannabis) at first...probably because of the way I was raised. But it has been a positive experience.” The patient takes cannabis daily (dosing recommended via Rick Simpson Oil method; http://bit.ly/2c55yG2). She prefers oil or chocolate (edibles) and orders her cannabis online for home delivery from an approved medical dispensary.
As an appetite stimulant, dronabinol is FDA approved for the treatment of anorexia-associated with weight loss in patients with HIV/AIDS; however, it is not clear whether this effect may stimulate calorie intake or enables fat/water accumulation rather than add lean body mass.2
Once again, enough evidence supporting the use of cannabinoids for cancer-associated anorexia has not been allowed to build,2
despite the fact that some patients report advantages (Case Study)