Published Case Studies and a Clinical Trial Showing Cannabis Produces Anticancer Effects in Humans
Over the past decade, most cases of cannabis fighting cancer in humans have been reported by patients themselves on social media or featured in stories from conventional media outlets. While these stories are powerful, they are understandably considered a lower form of evidence due to their self-reported nature. However, there are now several case studies or case series published in formal medical journals which associate phytocannabinoid intake with anticancer effects in humans.
Spontaneous Regression of Septum Pellucidum/Forniceal Pilocytic Astrocytomas — Possible Role of Cannabis Inhalation
A 2011 article published by doctors with the Division of Pediatric Neurosurgery at BC Children’s Hospital in Canada was the first to link some form of cannabis intake with tumor regression. Two children with astrocytoma tumors underwent surgery to remove the tumors, although a small amount of residual tumor tissue was left in each case. After the first three years of follow-up, one tumor remained the same while the other slightly increased in size. During the second three-year surveillance period, both tumors regressed, despite the absence of conventional treatment. As the authors stated, “The tumors regressed over the same period of time that cannabis was consumed via inhalation, raising the possibility that the cannabis played a role in the tumor regression.”
Cannabis Extract Treatment for Terminal Acute Lymphoblastic Leukemia with a Philadelphia Chromosome Mutation
This 2013 case study was apparently the first to examine the impact of tetrahydrocannabinol (THC)-rich cannabis oil on cancer. A 14-year-old female patient with an aggressive form of leukemia initially received chemotherapy and radiation treatments for nearly three years; however, these measures failed to stop the cancer and the patient was placed in palliative home care. Cannabis oil was used as a last resort. The first dose was given on February 21, 2009. Prior to this, from February 4th to the 20th, the patient’s leukemic blast cell count rose from 51,490 to 194,000. Even after beginning the oil, the count continued to rise, peaking at 374,000 on February 25th. However, there was subsequently a sharp decrease in blast count, which correlated with an increase in the cannabis doses. By Day 39, the blast count had dropped to 300. The total treatment lasted 78 days, at which point the leukemic blast cells were almost completely gone. Unfortunately, the patient passed away from a bowel perforation that was reportedly caused by side effects from the high doses of previously administered chemotherapy. The doctors concluded:
“These results cannot be explained by any other therapies, as the child was under palliative care and was solely on cannabinoid treatment when the response was documented by the SickKids Hospital. The toxicology reports ruled out chemotherapeutic agents, and only showed her to be positive for THC when she had ‘a recent massive decrease of WBC from 350,000 to 0.3′ inducing tumor lysis syndrome, as reported by the primary hematologist/oncologist at the SickKids Hospital.” Tumor lysis syndrome can result from the toxins released when cancer cells are killed.
*Note: Hemp oil refers to THC-rich cannabis oil in this context, not hemp-derived CBD-rich oil
Interestingly, a report in 2016 from German doctors at the University Hospital Tübingen further supported the potential of THC to fight leukemia. They stated, “We have anecdotal evidence that THC may have contributed to disease control in a patient with acute undifferentiated leukemia.” The nature of this evidence was quite indirect though, as the doctors extracted blood plasma from an elderly patient treated with dronabinol (synthetic THC) and then cultured leukemia cells in the plasma. The patient received no other anticancer treatment. Doctors found there was an inhibitory effect of the plasma on the cells, and stated, “This observation argues for an antileukemic activity of dronabinol in vivo [in this case, in vivo refers to a human, not animals]. Indeed, one concern about using cannabis to treat cancer is that effective anticancer doses are not possible to obtain. This study offers evidence alleviating that concern. However, it was not entirely clear if a control experiment was conducted (testing dronabinol-free plasma on Jurkat leukemia cells). In any case, it was concluded that the study supported THC as a potential low-toxic therapy option for a subset of acute leukemia patients.
Medical Cannabis in the Palliation of Malignant Wounds – A Case Report
A case report describing a patient with recurrent squamous cell carcinoma who used vaporized cannabis and topically-applied cannabis oil was published in 2017 by a physician with the University of Toronto (full text here). Although the patient was mainly seeking pain relief, there was indication of an antitumor effect. Vaporization of 0.5g to 1.0g of dried cannabis (7.25% THC/8.21% CBD) allowed him to discontinue some pain medications and tremendously reduce others. He switched to topical use of a cannabis-infused sunflower oil (5.24% THC/8.02% CBD) after vaporization became impractical. As the chart below shows, the tumor size was increasing rapidly until it reversed course once topical treatment commenced.
The report’s author stated, “Before the use of topical MC oil, the patient’s wound was growing rapidly. Yet, after a few weeks, a modest regression of his malignant wound was observed while the patient used topical MC. This secondary outcome suggests that topical MC may promote antineoplastic activity as per the findings of Casanova et al. [referring to a study showing cannabinoid receptor activation reduces skin tumor growth].” Unfortunately, the patient still passed away from apparent metastasis of the cancer. This is not surprising; the oil used here was substantially weaker than oils reportedly used by other skin cancer patients – 13% vs. 50-80% in more concentrated extracts. Furthermore, the patient ingested very little cannabis internally. This action would have been needed to potentially fight metastasis. Nonetheless, the charted growth of the tumor strongly suggests an antitumor effect of cannabis.
Case Report: Clinical Outcome and Image Response of Two Patients With Secondary High-Grade Glioma Treated With Chemoradiation, PCV, and Cannabidiol
A pair of case reports published in January 2019 by Brazilian doctors examined the use of CBD along with surgery, chemotherapy, and radiation for high-grade gliomas. Patient 1, a 38-year-old male, was diagnosed with Grade II astrocytoma in August 2010 after a partial surgical resection. Subsequent chemotherapy with temozolomide from 2011-2013 prevented regrowth until 2015, leading to recontinuation of a lower dose of temozolomide in March 2015. Proving ineffective, the dose was increased in June 2015, yet the tumor continued to grow. The temozolomide was discontinued in January 2016 and another surgery was planned, followed by radiation and a new combination of chemotherapy known as PCV (procarbazine, lomustine, and vincristine) which lasted six cycles (administered for 5 days every 28 days). After the second surgery, the diagnosis had progressed to Grade IV glioblastoma. At this time CBD was also administered at a dose of 300-450mg/day. The patient experienced few symptoms of nausea or fatigue and was still able to practice sports.
One month after the end of the chemotherapy and radiation, a phenomenon known as pseudoprogression occurred (increased swelling and inflammation), which resolved after a short period. As the authors state, pseudoprogression “does not represent a progression of the disease, and is often a marker of longer survival, presumably because it represents a robust response to treatment… The anti-inflammatory and neuroprotective actions of CBD may be related to the absence of side effects associated with PSD, such as headache, or changes relevant to tumor location.” The CBD used during the study, which lasted around 2 years, was from a full-spectrum hemp-derived CBD oil containing less than .3% THC. During their first year of treatment, patients also vaporized THC-rich cannabis flower.
Patient 2, also a 38-year-old male, was diagnosed with Grade II oligodendroglioma in April 2014 after surgical biopsy, with MRI showing an expansive, infiltrative lesion. He received temozolomide from September 2014 to July 2015, with no growth until an MRI revealed increased dimensions in February 2016. At this time the patient received a partial surgical resection, radiation, and six cycles of the PCV combination therapy. After this surgery, the glioma had progressed to Grade III. CBD was administered alongside the PCV at doses of 100-200mg/day. Like Patient 1, this patient was able to still practice sports and had few symptoms of nausea and fatigue.
The authors concluded, “Although this study only had two cases, it is interesting to note the good clinical and radiological evolution that might be related to this therapeutic association. Future randomized placebo-controlled trials with a larger number of patients are needed to confirm the study findings.”
Report of Objective Clinical Responses of Cancer Patients to Pharmaceutical-grade Synthetic Cannabidiol
A 2018 case series analyzed 119 cancer patients over a four-year period who used a synthetic form of CBD. One of the researchers involved was Dr. Wai Liu, whose preclinical work showing how CBD and other nonpsychotropic cannabinoids (cannabigerol, cannabigevarin, and their respective acid forms) fight leukemia has attracted some significant media attention. Clinical responses were observed in 92% of the patients, based on reductions in circulating tumor cells or reduction in tumor size. Most patients used between 20-60mg CBD per day. Several particularly notable cases were highlighted by the authors. For example, brain scans were included from a five-year-old with anaplastic ependymoma who underwent surgery, chemotherapy, and radiation. These treatments exerted no substantial effects as of January 2016. He began taking 20mg CBD per day in February 2016. A scan in April showed tumor progression, but subsequent September and December 2016 scans revealed substantial regression (60% volume decrease between February and December).
Other notable cases are quoted below.
“72/male – Prostate Cancer – Patient has had cancer immunotherapy, sono and photodynamic therapy (14) which was successful. On resumption of testosterone injections his prostate specific antigen (PSA) levels increased to 16. We started him on CBD early in 2015 at a dose of 10 drops twice a day (10mg), three days on and three days off. There was a reduction in circulating tumor cells (CTCs) with CBD alone from an initial 8.1 cells/7.5mL to 5.9 cells/7.5mL, then steady reduction over the course of 12 months of 4.8, 4.2, then 3.2 cells/7.5mL. He is still under treatment.”
“68/female – Breast cancer with bone metastases – Patient was diagnosed in March 2014 with progressive disease. She started local radiotherapy. We started her on CBD in January 2015, all subsequent scans showed stable disease. She has had no treatment other than CBD following radiotherapy.”
“65/female – Oesophageal cancer – Patient was diagnosed in May 2016. She had a stent put on place at that time and was given an expected survival of three months. Since then, she has been on CBD as the only treatment, and she has continued to refuse all standard treatments and investigations. We last saw her in November 2016, when she was looking well and had in fact regained weight. She died in January 2018.”
“65/female – Breast cancer – Patient was diagnosed in November 2009, and refused all conventional treatments and investigations. On examination she had a large fungating lesion 15cm in diameter in the left breast, and also palpable left axillary nodes. She began treatment with CBD in October 2014. We persuaded her to have radiotherapy in November 2014. She only agreed to have half the recommended treatment course. She has continued on CBD alone and on her last appointment the tumour in her left breast was 2cm in diameter, with no palpable axillary nodes.”
“62/female – Breast cancer – We first saw this patient in May 2014 and she has been on CBD, as the only treatment, since October 2014. We carried out various CTC tests in October 2014 which showed 10.6 cells per 7.5mL. Subsequent tests in July and October 2015, November 2016 and October 2017 showed CTCs to be 7.3, 6.8, 5.0 and 3.9 cells/7.5mL, respectively. Patient is currently stable with no symptoms.”
“67/female – Lobular breast cancer – Patient was diagnosed in November 2012. We first saw her in March 2014, we gave her CBD in October 2014, which is the only method of treatment. Initial CTCs in October 2014 was 9.3 cells per 7.5mL. Follow-up measurements in September 2015, March 2016 and March 2017 have been 7.5, 6.8, and 3.0 cells/7.5mL, respectively. All standard clinical investigations and scans have been normal since the beginning of 2015.”
Concomitant Treatment of Malignant Brain Tumours With CBD – A Case Series and Review of the Literature
Doctors affiliated with a hospital in Austria published a case series in the journal Anticancer Research in 2019 which documented the experiences of nine patients with brain tumors who used CBD as a component of their treatment. The doctors concluded, “By the time of the submission of this article, all but one patient are still alive with a mean survival time of 22.3 months (range=7-47 months). This is longer than what would have been expected.” The longer survival time is most logically indicative of a direct anticancer effect. Survival was also extended in the double-blind, placebo-controlled trial discussed at the end of this article.
Striking Lung Cancer Response to Self-Administration of Cannabidiol: A Case Report and Literature Review
Doctors with the Royal Stoke University Hospital in England published a case report in 2019 about a man who used CBD and subsequently experienced shrinking of his lung tumor. He was diagnosed with lung cancer in autumn 2016 and his oncologist gave him 6-12 months to live without treatment. Given the patient’s age of 83, he declined the treatment to maintain his quality of life. He did nothing until a friend suggested he try CBD oil, so he began using a legal version purchased from a health store in September 2017, starting with 2 drops (1.32mg CBD) twice daily for a week and then 9 drops (6mg CBD) twice daily until the end of September. It is unclear if this dosing continued into October. Before using CBD, his cancer measured between 30-40mm, which was apparently the primary tumor. In November 2017, a CT scan revealed near total resolution of the apparent primary tumor and showed most lymph nodes were normal size.
The doctors concluded, “In summary, the data presented here indicate that CBD may have had a role in the striking response in a patient with histologically proven adenocarcinoma of the lung as a result of self-administration of CBD oil for a month and in the absence of any other identifiable lifestyle, drug or dietary changes.” Another scan from January 2018 showed further stability; although this scan was not shown, the original diagnostic scan and post-CBD November 2017 scan were included and shown below.
Pre-CBD October 2016
Post-CBD November 2017
Dramatic Response to Laetrile and Cannabidiol (CBD) Oil in a Patient with Metastatic Low Grade Serous Ovarian Carcinoma
Another case study in 2019 by doctors with the UC San Diego Moores Cancer Center and UC San Diego School of Medicine reported on an 81-year-old patient with metastatic low grade serous ovarian carcinoma (LGSOC). In April 2017, the patient underwent surgery to have some cancerous tissue removed, and a May 2017 CT scan revealed several more soft tissue masses. The cancer was officially diagnosed as LGSOC, being positive for both estrogen and progesterone receptors.
Doctors recommended chemotherapy, but the patient declined due to concerns about quality of life. She instead pursued treatment with Laetrile tablets (500mg orally four times per day) and CBD oil (1 drop sublingually each evening) starting in May 2017. Her CA-125 level was measured to ascertain the status of the cancer, and immediately began to decline after the dual therapy started, as shown by the chart below. The potential contribution of each therapy is discussed later.
Another CT scan in July 2017 showed a decrease in the size of several masses. In November 2017, a further scan showed “dramatic reduction” in disease burden, as all identified lesions were almost completely resolved. The final assessment noted in this article occurred in December 2018 and revealed continued response to treatment.
This case is complicated by the combined use of Laetrile and an apparently very low dose of CBD that was not fully characterized. However, the authors noted that Laetrile, a semi-synthetic version of amygdaline (a naturally-occurring compound in some plants), has not been shown to be effective against cancer in any clinical trials. It is also a dangerous compound that is not recommended due to the risk of cyanide poisoning. Given this evidence, it is unlikely that Laetrile exerted any anticancer effect. However, there has seemingly never been a report of such a low dose of CBD exerting an anticancer effect before, raising the possibility this case may have been a spontaneous remission. Nonetheless, the previously discussed lung cancer case also involved low-dose CBD ingestion, so it’s possible that in some cases, especially among elderly patients, even low doses of CBD may produce an anticancer effect.
Cannabidiol Possibly Improves Survival of Patients with Pancreatic Cancer: A Case Series
The same team that published the peer-reviewed paper “Concomitant Treatment of Malignant Brain Tumours With CBD – A Case Series and Review of the Literature”, discussed earlier, also published a case series in 2020 featuring patients with pancreatic cancer who used CBD. While this paper has apparently not undergone the full peer-review process yet, the results come from a team with a previously published peer-reviewed article on similar subject matter. Nine patients were followed; all used chemotherapy along with CBD except for two who only used CBD. The daily dose was usually 400mg CBD, and the average overall survival was 11.5 months. As with the previous case series, survival was significantly extended with this protocol. The doctors concluded that overall survival was about two times longer than reported in a recent population-based study of pancreatic cancer patients.
The Effect of Cannabis in the Treatment of Hodgkin’s Lymphoma in a Pregnant Patient – Extensive Case Report and Literature Review
In 2021, a case report of a Romanian woman who used cannabis to treat Hodgkin’s lymphoma during pregnancy was published in the Journal of the Balkan Union of Oncology by doctors with the University of Oradea. The full PDF is found here. The patient was diagnosed with Stage IIB Hodgkin’s lymphoma (HL) in 2009 and treated with chemotherapy and radiation, which led to incomplete remission as a persistent 2cm tumor remained in the thorax. The cancer was largely dormant until 2014 after the patient became pregnant, when an MRI scan and biopsy revealed an apparently new tumor in the thorax, which was again confirmed to be HL and apparently measured 15 x 13cm. The patient refused the recommended chemotherapy and the child was eventually born by C-section.
In 2015, the patient became pregnant again and refused to terminate the pregnancy. The HL continued to progress, and symptoms were managed primarily with analgesic treatments. At 26 weeks of this second pregnancy, the patient began using cannabis oil topically and orally, ingesting between 1mL and 5mL 3 times per day. The potency and constituents of the oil were not reported, and it is unclear whether the oil was dominant in THC or CBD. Nonetheless, the patient’s pain and quality of life improved, and, apparently, the dimensions of the 15 x 13cm thorax tumor reduced to 8.3cm (the description of the reduction in this case is obscure). Sometime after the second baby was delivered by C-section, the patient’s condition progressed to Stage IV HL, and she began using a variety of conventional treatments in 2016 and 2017 including chemotherapy, immunotherapy, and surgery. She apparently did not use any treatments from 2017 to 2019, and resumed chemotherapy in 2019. It was unclear if she was still using cannabis at this time. As of the article’s publishing, it is also unclear what the patient’s status is.
Despite the particular complexity of this case, the fact the patient experienced a reduced tumor burden while taking cannabis oil is notable. The authors stated, “Cannabinoids affect many essential cellular processes and signaling pathways which are crucial for tumor development, as they can induce cell cycle arrest, promote apoptosis, and inhibit proliferation, migration and angiogenesis in tumor cells. In this way we explain the macroscopic tumor reduction in this patient after starting oral medical cannabis.” More information will eventually be included here if able to be obtained.
A Phase 1b Randomised, Placebo-Controlled Trial of Nabiximols Cannabinoid Oromucosal Spray with Temozolomide in Patients with Recurrent Glioblastoma
This trial by the pharmaceutical company GW Pharmaceuticals initially had details revealed in a press release in 2017, and in February 2021 was finally formally published in the British Journal of Cancer. 21 patients were randomized to receive chemotherapy and placebo or chemotherapy and phytocannabinoids in Part 2 of the study (Part 1 was an open-label structure; all patients in Part 2 were different from those participating in Part 1). The phytocannabinoid formulation was nabiximols, also known as Sativex, which is about a 1:1 formulation of THC and CBD containing 2.7mg/spray THC and 2.5mg/spray CBD. Patients started with one spray per day and worked up to a maximum of 12 sprays per day, resulting in a maximum dose of 32.4mg THC and 30mg CBD per day.
The 1-year survival analysis showed that 10 of 12 (83.3%) of patients in the nabiximols group were still alive, compared to 4 of 9 patients (44.4%) in the placebo group. At 2 years, the survival rate was 50% in the nabiximols group and 22% in the placebo group. The median overall survival was estimated to be 21.8 months in the nabiximols group and 12.1 months in the placebo group.
Weaknesses in this trial include the low number of participants and the confounding factor of two patients in the placebo group dying within the first 40 days. However, the results are still impressive and most likely demonstrate an anticancer effect of phytocannabinoids in the treatment of glioblastoma.
Summary
It is clearly remarkable that so many case studies have been published concerning an anticancer effect of phytocannabinoids. Given that both phytocannabinoids and endocannabinoids are consistently shown in preclinical studies to kill or inhibit numerous types of cancer cells through similar mechanisms, it is not surprising that phytocannabinoids appear to be producing responses in humans. Furthermore, since at least 2008, patients have been reporting through various media that high doses of phytocannabinoids have induced full or partial remissions of their cancers. Frankly, it is beyond logical possibility that phytocannabinoids have never, in a single case, produced an anticancer effect in humans. The number of coincidences required for that to be the reality are just too much.
Even though phytocannabinoids can clearly fight cancer in at least some cases, there is still far more to learn about phytocannabinoid therapy for cancer. What are the ideal dose protocols for different patients with different cancers? What types of cannabis should be used? Is there the possibility that cannabis could interfere with some treatments, as has been indicated with immunotherapy? For now, there are no clear answers and it will take a long time to get them. However, one thing is clear. Cancer patients anywhere in the world should be allowed to use cannabis medicine under their doctor’s supervision, and willing terminal cancer patients should be provided free or low-cost cannabis medicine given the very real chance it could save or extend their lives. Many patients do not have time to wait, not even a single day, and the evidence is more than strong enough to justify access to cannabis medicine now.
