Medical Marijuana
“ I was surprised by the low number of patients with hematologic malignancies in the study because we see a large number of those patients here , including many transplant patients ,” Dr . Pergam explained . “ But I think because of concerns about infection risk , patients with [ hematologic malignancies ] are either less interested or are talked out of using medical cannabis . Perhaps the messaging from their clinicians is different .”
Clinicians and the Cannabis Conundrum
For physicians , concerns about patients ’ cannabis use boils down to two broad questions : What are the health risks associated with cannabis use , including potential adverse effects ? Are patients using the agent without their health-care team ’ s knowledge , and , if so , why ?
“ There really are some benefits to medical marijuana ,” Dr . Casarett said in a 2016 TEDMed Talk . “ Those benefits may not be as huge or as stunning as some of the most avid proponents of medical marijuana would have us believe , but they are real .” 18 However , “ medical marijuana does have some risks . Those risks may not be as huge and as scary as some of the opponents of medical marijuana would have us believe , but they are real risks , nonetheless .”
In addition to the rare occurrences of aspergillosis respiratory infections , the risks associated with the inhalation include more frequent chronic bronchitis episodes , higher forced vital capacity , asthma development or exacerbation , and chronic pulmonary obstructive disease . 11
“ We need to talk about this with patients . ... The risks and benefits of cannabis use can be very different according to the patient ’ s situation .”
— STEVEN PERGAM , MD , MPH
In a meta-analysis of oral cannabinoids for antiemesis , AEs associated with the therapy included paranoid delusions , hallucinations , dysphoria , and depression . 7 The AEs were enough to convince some patients to leave studies , the authors noted .
The connections between cannabis and other AEs are more tenuous . There is limited or insufficient evidence to link the use of cannabis to a higher risk for the development of solid tumors or hematologic malignancies , such as AML and acute lymphocytic leukemia , or to an increased risk for cardiovascular disease or type 2 diabetes . 11
Dr . Pergam emphasized that he would not recommend cannabis use for patients who are immunocompromised or have neutropenia . Also , obviously , “ if someone has respiratory health issues , I wouldn ’ t recommend that they smoke it ,” he noted .
Dr . Abrams pointed out that , to date , no studies have shown botanical-pharmaceutical interaction between cannabis and prescription medications in patients ’ plasma concentrations . A pharmacokinetic study of 21 patients with chronic pain who were taking sustained-release opioids for pain management showed that , when patients also used vaporized cannabis , there was no significant effect on plasma levels of the opioid . 19 There was also a suggestion of enhanced analgesia , meaning that combining the two drugs could allow for opioid dose reductions .
Findings from ongoing studies also should alleviate some concerns that cannabis use could reduce the effectiveness of established chemotherapy agents . In in vitro and animal models , pairing cannabis extracts with chemotherapy agents led to a synergism in reducing cell numbers , with no negative effect on anti-cancer function . Cell cultures from different solid tumors have been investigated with several antineoplastic agents – gemcitabine , paclitaxel , 5-fluorouracil , among others – and synergism in inducing cancer cell death was a common finding . 20
Some Pot in Every Kitchen ?
Although clinicians may want further evidence that cannabis does more good than harm , patients are generally on board with using cannabis for symptom management . In the cross-sectional , anonymous survey by Dr . Pergam ’ s group , 66 percent of the respondents said they had used cannabis at some point in their lives , and almost one-fourth considered themselves to be active cannabis users .
Most respondents also expressed a strong interest in learning about cannabis during treatment ; 74 percent wanted information from their cancer-care providers , but less than 15 percent reported that they received such information . 17
That is problematic , according to the experts . Even for physicians who practice in a state where marijuana has not been legalized , conversations about use , or interest , in cannabis is important . “ We need to talk about this with patients . If we ’ re not asking questions about cannabis use , then we ’ re doing a disservice to them ,” Dr . Pergam said . “ Even though we don ’ t always know the best answer , having that discussion allows it to be a shared decision . The risks and benefits of cannabis use can be very different according to the patient ’ s situation .”
For example , Dr . Pergam said he would not recommend cannabis use for a patient about to undergo a bone marrow transplant , but it may be suitable for a patient with late-stage cancer who is looking for palliative relief . Again , he emphasized that if patients don ’ t ask their physicians about cannabis , they ’ ll get information elsewhere . “ I ’ m a little more skeptical of where the other data come from ,” he said .
Dr . Abrams agreed that he would hesitate to suggest cannabis use for certain patient populations , such as older patients with certain comorbidities , including cardiovascular disease . “ Cannabis could raise or lower blood pressure , increase pulse , and put a strain on the heart ,” he explained . “ Or if it causes orthostatic hypertension , it could lead to falls , and that ’ s not good in older people . I ’ m also a bit more cautious recommending it for people who have had a prior negative experience with [ recreational ] cannabis .”
As public opinion about medical cannabis shifts , and as more legislative bodies accept cannabis for medicinal use , physicians can no longer hide behind the excuse of too-little evidence-based medicine to avoid the topic with their patients – or to advise patients against cannabis use altogether , Dr . Abrams said .
“ As an integrative oncologist , I notice that the default mechanism for conventional oncologists is to tell patients to stop using all botanicals and supplements when their liver function tests are elevated ,” he said . “ More often than not , though , the chemotherapy is elevating liver function . But people have blinders on and are willing to blame everything on the botanicals .”
A more open discussion about cannabis use will also allow scientists to pinpoint possible drug interactions and more effectively manage patients ’ treatment , Dr . Casarett stressed . “ Potential interactions with other drugs is the most important reason why health-care providers need to be proactive in engaging their patients in discussions ,” he wrote . “ We can ’ t provide guidance and counseling if we don ’ t know whether – and why – our patients are using medical cannabis .”— By Shalmali Pal ●
REFERENCES
1 . U . S . Drug Enforcement Administration . “ DEA Drug Fact Sheet : Marijuana .” Accessed November 2 , 2017 , from https :// www . dea . gov / druginfo / drug _ data _ sheets / Marijuana . pdf .
2 . U . S . Drug Enforcement Administration . “ DEA Announces Actions Related to Marijuana and Industrial Hemp , August 11 , 2016 .” Accessed November 2 , 2017 , from https :// www . dea . gov / divisions / hq / 2016 / hq081116 . shtml .
3 . U . S . Food and Drug Administration . “ Marinol prescribing information .” Accessed November 2 , 2017 , from https :// www . accessdata . fda . gov / drugsatfda _ docs / label / 2016 / 205525s000lbl . pdf .
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6 . American Cancer Society . “ Marijuana and Cancer .” Accessed November 2 , 2017 , from https :// www . cancer . org / treatment / treatments-and-side-effects / complementaryand-alternative-medicine / marijuana-and-cancer . html .
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11 . National Academies of Science , Engineering , and Medicine . “ The Health Effects of Cannabis and Cannabinoids : The Current State of Evidence and Recommendations for Research 2017 .” Accessed November 2 , 2017 , from https :// www . nap . edu / catalog / 24625 / the-health-effects-of-cannabis-and-cannabinoids-the-current-state .
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13 . Mukherjee S , Fu AZ , Mansour M , et al . Cigarette smoking significantly increases the risk of invasive fungal disease ( IFD ) in acute myeloid leukemia ( AML ) patients undergoing induction chemotherapy . Abstract # 3595 . Presented at the 2011 ASH Annual Meeting , December 12 , 2011 ; San Diego , CA .
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17 . Pergam SA , Woodfield MC , Lee CM , et al . Cannabis use among patients at a comprehensive cancer center in a state with legalized medicinal and recreational use . Cancer . 2017 September 25 . [ Epub ahead of print ]
18 . Casarett D . “ A Doctor ’ s Case for Medical Marijuana - TEDMed 2016 .” Accessed November 2 , 2017 , from https :// www . ted . com / talks / david _ casarett _ a _ doctor _ s _ case _ for _ medical _ marijuana .
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20 . Ward SJ , McAllister SD , Kawamura R , et al . Cannabidiol inhibits paclitaxel-induced neuropathic pain through 5-HT1A receptors without diminishing nervous system function or chemotherapy efficacy . Br J Pharmacol . 2014 ; 171:636-45 .
112 ASH Clinical News December 2017