For Cancer, Cannabis Has Many Virtues, Says Large Study

Nick Mulcahy

March 19, 2018

Cannabis, or marijuana, may improve a variety of cancer-related symptoms, including nausea and vomiting, sleep disorders, pain, anxiety, and depression, conclude the authors of a 2960-patient observational study from Israel.

The study was published online March 5 in the European Journal of Internal Medicine.

It provides a large-scale portrait of who used medical cannabis for what cancers, and what benefits they derived during a 6-month period.

The study population consisted mostly of patients with advanced-stage cancers (51.2%, stage 4). At 6 months, about 25% of the study population had died.

Of the 1742 patients who survived to 6 months and who finished the study protocol, 60% achieved "treatment success," report Victor Novack, MD, PhD, director of the Cannabis Clinical Research Center and Research Authority, Soroka University Medical Center, Beersheba, Israel, and colleagues

The study's primary efficacy outcome was treatment success, which was defined as moderate or significant improvement in patients' overall condition at 6 months, as well as not quitting treatment and not having serious side effects.

Notably, factors associated with success were previous experience with cannabis, high levels of pain, young age, and lack of concerns regarding possible negative effects of cannabis treatment.

With its effect on multiple symptoms, cannabis is a "desirable therapeutic option" for cancer patients, who often have multiple complaints, conclude the authors.

This is an "interesting and important study" in the field, said Mark S. Wallace, MD, professor of clinical anesthesiology at the University of California, San Diego, who was asked for comment.

Wallace highlighted the large number of patients as a study strength. He also believes in the drug's efficacy. "I use cannabis a lot in my cancer population, with very positive results," he said.

Palliation of Cancer Symptoms

Israel has a relatively lengthy experience with medical cannabis. The Ministry of Health in Israel approved its use in 2007. The primary use is palliation of cancer symptoms.

However, until now, there have been limited data on the epidemiology of Israeli cancer patients who use the drug and on the adverse effect and efficacy profile of their cannabis treatment.

"We feel that it is absolutely imperative to accelerate the development of the scientific research program [of cannabis] within the paradigm of evidence-based medicine," Novack told Medscape Medical News in an email.

The new study was carried out by Novack in collaboration with other Israeli academics and with employees of Tikun-Olam ("repair the world" in Hebrew), a private Israeli company that grows medical cannabis, operates clinics, and conducts research on medical cannabis.

For the study, the team reviewed data from questionnaires at baseline, at 1 month, and at 6 months on nearly 3000 cancer patients who were prescribed medical cannabis between 2015 and 2017.

The mean age of the patients was 59.5 years; about half (43.1%) were older than 65 years. Most patients were either retired (31.8%) or did not work (46.9%). During the 6-month period before commencing cannabis treatment, 53.9% were hospitalized (median number of days, 10). There were slightly more women (54.6%) than men in the study.

About one quarter (26.7%) of patients had previous experience with cannabis.

The main types of malignancy included those of the breast (20.7%), lung (13.6%), pancreas (8.1%), and colon (7.9%), as well as lymphoma (4.9%). The median time from cancer diagnosis was 6 months.

The patients predominantly used four different cannabis strains that differed in Δ9-THC/CBD concentration. Cannabis was consumed as oil or through inflorescence ingestion via capsules, cigarettes, and flowers. "Unfortunately, 45% of our patients chose smoking as a delivery method. The rest were treated with oil, evaporator, or capsules," commented Novack.

The study design included a protocol for the starting dose and subsequent titration. Establishing an appropriate dose is important for patients outside of clinical trials, suggested Wallace. "Many of the cancer patients I see for the first time are using cannabis with mixed results but are not receiving guidance on dosing. Once we provide this to them, many of them get better results," he told Medscape Medical News.

At baseline, patients reported an average of 11.1 symptoms. The problems most commonly reported were sleep troubles, pain (with median intensity of 8 of 10 on a well-established scale), weakness, and fatigue.

The investigators report that the symptoms that improved the most among the patients were nausea and vomiting (91.0%), sleep disorders (87.5%), restlessness (87.5%), anxiety and depression (84.2%), pruritus (82.1%), and headaches (81.4%).

The team acknowledges that, owing to the observational nature of the study, "no causality between cannabis therapy and symptom improvement can be established."

Tally of Success

A total of 3619 patients initiated cannabis treatment; at 1-month follow-up, some had either died (6.7%) or had stopped treatment (10.8%).

At 6 months' follow-up, 2968 patients had continued since month 1. Additional deaths occurred, and additional patients either left the study or failed to respond to the final questionnaire. The investigators report that 1046 (60%) of 1742 patients had treatment success at 6 months.

Table. Factors Associated With Treatment Success

  Odds Ratio 95% Confidence Interval P Value
Age 0.98 0.98 - 0.99 <.001
Pain scale 1.06 1.03 - 1.09 <.001
Concerns with cannabis treatment 0.57 0.44 - 0.73 <.001
Previous experience with cannabis 1.32 1.05 - 1.66 <.05


Treatment success rates for the different cancers (17 in total) varied. At the high end, 69.2% of renal cancer and Hodgkin lymphoma patients achieved treatment success. Other cancers for which there were high rates of treatment success included brain/central nervous system tumors in adults (67.8%), multiple myeloma (67%), and cervical cancer (66.6%). The lowest success rates were seen in patients with prostate cancer (53.4%) and melanoma (31.2%).

A Focus on Pain

According to the study authors, previous research indicates that most patients (all conditions) who use cannabis medically do so for pain. In the current study in cancer patients, 52.9% of patients reported their pain to be "very high" (scores of 8 to 10 on a 10-point visual analogue scale) prior to treatment initiation. Only 4.6% reported having pain of this intensity after 6 months of treatment (P < .001).

Cannabis also helped the study patients reduce use of a variety of drugs for pain relief and related cancer conditions, Novack and colleagues report.

During the study period, 35.1% of participants reported a decrease in drug consumption. These decreases were reported for drugs in the following categories: other analgesics and antipyretics, hypnotics and sedatives, corticosteroids, and opioids.

Opioids were the most prevalent drugs used by participants at the study's start (344 patients). Notably, at 6 months, 36% of those patients had stopped taking opioids, and 9.9% had decreased the dose; 51.1% continued to take the same dose, and 1.1% increased the dose. An additional 32 patients started treatment with opioids during the 6 months of follow-up.

These findings are consonant with Wallace's experience. "I have consistently seen a reduction in opioid use with administration of medical cannabis," he told Medscape Medical News.

The most common side effects of medicinal cannabis reported by these cancer patients at 6 months were dizziness (8.0%), dry mouth (7.3%), increased appetite (3.6%), sleepiness (3.3%), and psychoactive effect (2.8%).

The most common reported reasons for treatment discontinuation were lack of an ongoing need (28.9%), no therapeutic effect (22.5%), and side effects (19.3%).

The study was funded by Tikun Olam. Dr Novack is a paid member of the Tikun Olam Scientific Advisory Board. Dr Wallace has consulting relationships with Insys and Zynerba.

Eur J Int Med. Published online March 8, 2018. Full text

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