Chronic pain affects 20% of the general population and over 50% of cancer patients. Uncontrolled chronic pain impairs quality of life, exacerbates pre-existing comorbidities, and may lead to depression and anxiety [5, 6]. Opioids remain one of the mainstay treatments for chronic cancer-related pain. Developing opioid tolerance due to chronic use, significant adverse effects, and potential for addiction are deterrent factors that may lead to pain undertreatment in cancer patients [7, 8]. Furthermore, patients with severe chronic pain are at risk of accidental opioid overdose, especially when used concomitantly with benzodiazepines and/or alcohol [9].

Accumulating evidence suggests the safety and efficacy of MM in the treatment of both chronic non-cancerous pain and cancer-related pain. A systematic review with thirty-six trials assessed the efficacy of different MM formulations (sprays, oral, and smoked) to treat non-cancer neuropathic and non-neuropathic pain. In the sixteen evaluable trials, prolonged cannabinoid treatment (two to eight weeks), as opposed to placebo, was associated with a significantly greater reduction in pain (weighted mean difference on a pain visual analog scale was −0.68, 95% confidence interval −0.96 to −0.40, I2 = 8%, P <0.00001) [1]. In patients with advanced cancer with moderate chronic pain, Lichtman et al. observed that administration of nabiximols spray was associated with a median 15.5% improvement in average pain score as opposed to 6.3% with placebo (P=0.0378) [3]. In an observational study, different formulations of THC and CBD (oil, capsules, and cigarettes) were provided to 3,619 patients with severe cancer-related pain (median baseline pain score of 8/10) [2]. In participants who remained on cannabis at six-month follow-up (N=1997, 55%), only 4.6% reported ongoing severe pain. Concomitant opioid use was decreased and stopped respectively in 10 and 36% of patients.

MM showed a positive safety profile in these studies. Treatment-related adverse events were reportedly mild to moderate, and the most common effects were somnolence, dry mouth, increased appetite, dizziness [1–3, 10]. Of significant note, fatal overdose secondary to marijuana use is uncommon as opposed to opioids which caused more than 46,000 deaths per year [11]. However, the majority of patients diagnosed with E-cigarette or vaping product use associated lung injury (EVALI) have reported use of THC-containing smokeless products [12, 13] and, albeit rare, deaths have been reported [14]. Moreover, there is lacking evidence on long-term effects of cannabinoids.

The United States is experiencing progressive legalization of marijuana for recreational and medicinal purposes. Notwithstanding, limited evidence points to low levels of education on medical cannabis amongst healthcare professionals. In a survey distributed to pharmacy students from six colleges in Ohio, students endorsed low medical marijuana knowledge and felt more education is needed in pharmacy schools [15]. In the same study, medical marijuana education was provided in less than two-thirds of 79 colleges located in MM legal states. In another single-center Spanish study, surveyed nursing students were unaware of indications of medical marijuana. Less than one percent received some type of education regarding cannabis, while more than 85% felt the need to incorporate cannabis education to their curriculum [16]. In another study by Philpot et al., 62 primary healthcare providers in a large healthcare system in Minnesota were surveyed about their attitudes and beliefs about MM. Similar to our findings, their survey concluded that a significant proportion of providers were not comfortable answering patients’ questions about MM, though were willing to receive more related education [4].

To the best of our knowledge, this is the first study to observe a critical lack of knowledge in MM in in-training IM residents. Hence, it is worth implementing a curriculum for resident physicians that includes indications, medication interactions, and side effects of MM use. Questions related to substance use disorder comprised less than two percent in the American Board of Internal Medicine (ABIM) certification exam [17]. Medical Knowledge Self-Assessment Program (MKSAP) offered by the American College of Physicians (ACP), a popular study material for ABIM certification exam used by internal medicine residents, does not include any detailed section regarding the indications, contraindications, or adverse effects of cannabinoids [18]. This might lead to a lack of preparedness of residents as frontline providers. Indeed, cannabis use is augmenting due to the increasing number of legalizing states, expansion of its off-label uses, and generalization of recreational uses. Physicians should be familiarized with its use, as well as with the management of MM-related toxicities. At the same time, qualifying conditions for MM use vary depending on the state of practice. Local graduate medical education offices should incorporate pertinent curriculum while keeping up pace with federal and state policy changes.

Our survey results were based on a single-institution experience from an academic center located in New York. A significant percentage of surveyed trainees obtained their medical degrees from outside countries. Nevertheless, the present study emphasizes the lack of formal education on medical cannabis during IM residency training and not before it. Albeit the survey participation was limited, we believe the results were relevant as they show a general trend towards a lack of knowledge on medical cannabis and point to the necessity of a formal educational curriculum.