Cannabis inhalation is associated with spontaneous brain tumor regression in two subjects, according to a pair of case reports to be published in Child’s Nervous System, the official journal of the International Society for Pediatric Neurosurgery.

Investigators at the British Columbia Children’s Hospital in Vancouver documented the mitigation of residual tumors in two adolescent subjects who regularly inhaled cannabis. Authors determined that both subjects experienced a “clear regression” of their residual brain tumors over a three-year-period.

“Neither patient received any conventional adjuvant treatment” during this time period, investigators wrote. “The tumors regressed over the same period of time that cannabis was consumed via inhalation, raising the possibility that cannabis played a role in tumor regression.”

Researchers concluded, “Further research may be appropriate to elucidate the increasingly recognized effect of cannabis/cannabinoids on gliomas (brain cancers).”

A 2006 pilot study published in the British Journal of Cancer previously reported that the intratumoral administration of the cannabinoid THC was associated with reduced tumor cell proliferation in two of nine human subjects with brain cancer.

Separate preclinical studies assessing the anticancer activity of cannabinoids and endocannabinoids indicate that the substances can inhibit the proliferation of various types of cancerous cells, including breast carcinoma, prostate carcinoma, and lung cancer.

Commenting on the two new case reports, researcher Jahan Marcu — who has previously documented the inhibitory effects of cannabinoids on human glioblastoma cell proliferation and survival — wrote in the blog Freedom Is Green: “Can marijuana contribute to the regression or remission of certain cancers? Given the slow progress of clinical trials for whole plant Cannabis, it can be frustrating waiting for years, even decades, trying to answer these vital questions. But for the two young women with brain cancer in (this) report, a shift to a cannabis lifestyle may have made a difference.”

The administration of THC reduces the tumor growth of metastatic breast cancer and “might constitute a new therapeutic tool for the treatment” of cancerous tumors, according to preclinical data published online in the journal Molecular Cancer.

Investigators from Complutense University in Madrid assessed the anti-tumor potential of THC and JWH-133, a non-psychotropic CB2 receptor-selective agonist, in the treatment of ErbB2-positive breast tumors – a highly aggressive form of breast cancer that is typically unresponsive to standard therapies.

Researchers reported, “[B]oth Delta-9-tetrahydrocannabinol … and JWH-133 …reduce tumor growth [and] tumor number [in mice]. … [T]hese results provide a strong preclinical evidence for the use of cannabinoid-based therapies for the management of ErbB2-positive breast cancer.”

In 2007, investigators at the California Pacific Medical Center Research Institute reported that the administration of the nonpsychoactive cannabinoid CBD limited breast cancer metastasis in a manner that was superior to comparable synthesized agents.

Previous preclinical studies assessing the anticancer properties of cannabinoids have shown that they inhibit the proliferation of a wide range of cancers, including brain cancer, prostate cancer, oral cancers, lung cancer, skin cancer, pancreatic cancer, biliary tract cancers, and lymphoma.

Full text of the study, “Cannabinoids reduce ErbB2-driven breast cancer progression through Akt inhibition,” is available online here.

A just published scientific review by Sao Paulo University (Brazil) researcher Antonio Zuardi reports that there’s been an “explosive increase” of interest in CBD over the past five years. It’s apparent why.

“Studies have suggested a wide range of possible therapeutic effects of cannabidiol on several conditions, including Parkinson’s disease, Alzheimer’s disease, cerebral ischemia, diabetes, rheumatoid arthritis, other inflammatory diseases, nausea and cancer,” Zuardi writes. Let’s look at a few of these in detail, shall we?

1. Antiepileptic action
“In 1973, a Brazilian group reported that CBD was active in … blocking convulsions produced in experimental animals.”

2. Sedative action
“In humans with insomnia, high doses of CBD increased sleep duration compared to placebo.”

3. Anxiolytic action
“CBD induce[s] a clear anxiolytic effect and a pattern of cerebral activity compatible with an anxiolytic activity.”

4. Antipsychcotic action
“[C]linical studies suggest that CBD is an effective, safe and well-tolerated alternative treatment for schizophrenic patients.”

5. Antidystonic action
“CBD … had antidystonic effects in humans when administered along with standard medication to five patients with dystonia, in an open study.”

6. Antioxidative action
“[I]t was demonstrated that CBD can reduce hydroperoxide-induced oxidative damage as well as or better than other antioxidants. CBD was more protective against glutamate neurotoxicity than either ascorbate or a-tocopherol, indicating that this drug is a potent antioxidant.”

7. Neuroprotective action
“A marked reduction in the cell survival was observed following exposure of cultured rat pheochromocytoma PC12 cells to beta-A peptide. Treatment of the cells with CBD prior to beta-A exposure significantly elevated the cell survival.”

8. Antiinflammatory action
“CBD, administered i.p. or orally, has blocked the progression of arthritis.”

9. Cardioprotective action
“CBD induces a substantial cardioprotective effect.”

10. Action on diabetes
“CBD treatment of NOD (non-obese diabetic) mice before the development of the disease reduced its incidence from 86% in the non-treated control mice to 30% in CBD-treated mice. … It was also observed that administration of CBD to 11-14 week old female NOD mice, which were either in a latent diabetes stage or had initial symptoms of diabetes, ameliorated the manifestations of the disease.”

11. Antiemetic action
“The expression of this conditioned retching reaction was completely suppressed by CBD and delta9-THC, but not by ondansetron, [an] antagonist that interferes with acute vomiting.”

12. Anticancer action
“A study of the effect of different cannabinoids on eight tumor cell lines, in vitro, has clearly indicated that, of the five natural compounds tested, CBD was the most potent inhibitor of cancer cell growth.”

In sum, the past 45 years of scientific study on CBD has revealed the compound to be non-toxic, non-psychoactive, and to possess a multitude of therapeutic properties. Yet, to this day it remains illegal to possess or use (and nearly impossible to study in US clinical trials) simply because it is associated with marijuana.

What possible advancements in medical treatment may have been achieved over the past decades had US government officials chosen to advance — rather than inhibit — clinical research into CBD (which, under federal law, remains a Schedule I drug defined as having “no currently accepted medical use”)? Perhaps it’s time someone asks John Walters or the DEA?