Breast Cancer and Cannabis Treatment


One of the earliest and most widely adopted avenues for the medical community accepting cannabis treatment has come in the area of symptom treatment for cancer patients. Chemotherapy and radiation both force patients through a harrowing process with many of its own side effects. Although chemotherapy has made advances to make treatment more bearable in recent years, cannabis has proven itself surprisingly effective in treating symptoms.

Between helping to stimulate appetite, relieving chronic pain and dizziness, and helping anxiety, tens of thousand of patients have benefitted from symptom relief via cannabis use as a natural medicine. However, many studies have shown independently that beyond symptoms, cannabis may actually be capable of treating some forms of cancer. In this article, we’ll dig into the evidence pertaining to breast cancer, a very common and aggressive form.

Breast cancer, as with all forms of cancer, occurs when cells are duplicating too aggressively. Although there are around 20 variations, most result in tumors forming in the breast tissue which can then spread to other areas of the body and begin to shut down normal operation. Likelihood for developing cancer depends on both genetic variables and lifestyle, but specific risk factors include age, obesity, and high levels of certain hormones. Abnormally high amounts of hormones not only increase the likelihood of developing cancer, but they also increase the rate that the cancer progresses at. As such, breast cancer patients and survivors are often encouraged not to take additional hormones when considering birth control or menopause options. At this point in time, we have not fully mapped the hormonal effects of cannabis. For instance, it is completely unclear whether cannabis increases, decreases, or has no effect on release of estrogen. Some studies claim that estrogen is lowered, as cannabinoids compete for receptor sites, blocking active estrogen. However, we also know that cannabis can produce estrogen-like effects and has an extensive interaction with the endocrine system. THC has been shown to signal estrogen pathways and cannabis extracts also sometimes contain estrogen-like contaminants. From the current literature, it is therefore impossible to surmise the total effect on estrogen and other hormones that can increase cancer.

However, what we have confirmed is that cannabis and specifically cannabidiol has anti-cancer properties, especially in regard to breast cancer and more aggressive types. Numerous studies both in vivo and in vitro have confirmed that cannabis might have the potential to cure some forms of the disease. The first evidence came in the form of cell tests, with researchers administering CBD to cancerous cell colonies and observing proliferation or decline. Researchers have found in numerous cases and with many cancer cell lines, that adding CBD limits growth of cells. This evidence has been duplicated often and is what allows the medical community to confidently term cannabis as “anti-cancer”. Taking it further, several groups began to “infect” rodents with cancer (one specifically with breast cancer) both through grafts and other means. Afterwards, these groups directly injected CBD into the site of the tumor and observed effects. In these tests, tumor growth initially halted metastasis (spread of cancer), but the primary tumors acquired resistance to the inhibitory properties of CBD within one month. In other words, cancer shows an adaptive response to CBD treatment in at least some cases. As researchers trim down the search for which pathways are causing these anti-tumor effects, one group has found that down-regulating a specific DNA binding inhibitor (Id-1) via cannabis has been shown to cause tumor cells to self-destruct. This seems to be the most promising pathway of using cannabis to eradicate tumors (via indirect biochemical pathways). Tumor cells also tend to have more of a particular cannabinoid receptor than normal cells, which further underscores that there is at least a possible physiological basis for treatment.

Unfortunately, all of this evidence is terribly misleading for numerous reasons. First, cell culture experiments are next to value-less for anything other than preliminary inquiries. One cannabis study noted “it was presumed the anti-proliferative effect at the high concentration of extract was due to cell toxicity”. In other words, researchers added so much cannabis extract to the cell culture, that it made environmental conditions inhospitable for growth. Excessive water in a culture would do the same! Another issue is that limiting growth of cancer cells does not equate to eradicating cancer. It is very possible that cannabis could be preventative or help slow the rate of development, but no studies are reliably showing total eradication of tumors. On top of that, even the experiments routinely performed on mice often fail when translated to humans. History provides countless examples of cancer chemicals that work reliably in rodents but due to the increased complexity of the human body or differences in administration, do not work at all in humans. For instance, the type of cancer cell graft used on mice does not always interact in the same way with a rodent body that a non-graft, “naturally” occurring cancer would. Unfortunately, in the case of cancer research, selecting a range of same age, same growth condition mice that happen to have cancer at the same time and stage would be infeasible. Rodent evidence therefore in regards to cancer is “mockup” evidence at best. To date, only one clinical trial (involving real people) has been published; it involved merely nine subjects, meaning that from a statistical standpoint, the conclusions hold almost no weight. Science aside, common sense observations bear consideration. If mere presence of CBD in fatty body tissues prevents or limits cancer growth, why do we not see even a noticeable difference in cancer rates between cannabis users and non-users?

Realistically, an educated guess would be that in time, cannabinoid compounds or their synthetic analogues will be involved directly in chemotherapy and provide ways of modulating cell behavior in conjunction with other substances. It’s tempting to jump on the “cannabis cures cancer” bandwagon, and in fact, many of the proponents of cannabis employ such careless statements in their literature. However, genuine progress in cannabis treatment depends on resisting the same type of propaganda that shrouds traditional pharmacology. At this point in time, based on what we have seen, it seems overly optimistic to believe that cannabis will cure cancer alone.



Amy Alexander, Paul Smith & Rhonda Rosengren (2009) Cannabinoids in the treatment of cancer, Cancer Letters 285 (2009), 6-12.

Kazuhito Watanabe, Erina Motoya, Naoki Matsuzawa, Tatsuya Funahashi, et al. (2005) Marijuana extracts possess the effects like the endocrine disrupting chemicals, Toxicology 206 (2005), 471-478.

Sean D. McAllister, Ryuichi Murase, Rigel T. Christian, Darryl Lau, et al. (2011) Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastatis, Breast Cancer Res Treat (2011), 129:37-47. DOI 10.1007/s10549-010-1177-4