Cancer is the unregulated growth of cells and can occur in any location or organ system in the body. Overall, cancer is the second-leading cause of death in the United States , with an estimated 1,600+ deaths daily . It is also a significant cause of morbidity for patients, as they experiences the consequences of not only the cancer, but the therapies designed treat it. Common causes of increased morbidity include:
- Pain: cancer itself is often a significant source of pain. As a tumor expands, it can compress nerves and normal structures and lead to intractable pain that can be difficult to management. Surgery can improve these symptoms, but the surgeries themselves can sometimes leave patients with debilitating pain. Also, radiation therapy and many of the chemotherapy agents can damage normal tissue and nerves and lead to significant pain
- Nausea and vomiting: many cancer therapies are associated with nausea and vomiting. Even moderate symptoms can impact food intake, ability to maintain weight, and quality of life.
- Weight loss: cancers consume a tremendous amount of energy as they grow and the body uses vast resources to try to fight it off. The immune system also releases chemicals to cause inflammation in a body with cancer, decreasing the hunger drive. Cancer therapies often cause increased production of these inflammatory chemicals during treatment, worsening symptoms.
- Fatigue: both cancers and therapies can cause debilitating weakness and even as they recover, patients are often left bed-bound or unable to perform the normal functions of living.
- Psychiatric disorders: patients with cancer often experience depression during times of their disease and treatment, even when successful. Even when cured, patients often experience anxiety of a relapse.
STANDARD THERAPIES FOR CANCER
The standard therapies for cancer include one, or often multiple, of the following:
- Surgery: procedures to remove tumor can be curative if the cancer has not spread. Surgery is often combined with other treatments to improve outcomes.
- Chemotherapy: there are many chemotherapy agents, but many of them work essentially through the same mechanism – by inhibiting the ability of cells to proliferate. Unfortunately, these tend not to be targeted therapies to the goal is to kill the cancer cells faster than the normal cells and hope for a good outcome.
- Hormonal therapy: cancers sometimes have receptors for hormones. When these receptors are modulated, growth can often be affected and influenced to improve outcomes.
- Immunotherapy: newer therapies are starting to harness the body’s natural ability to fight cancer and amplify it.
As mentioned above, all of the above therapies can have significant side effects and in some people, can be more dangerous than the cancer itself. Multi-discipline teams are often charged to consider a patient as an individual and provide the best, and most appropriate, medical therapy.
CANCER AND MEDICAL CANNABIS
Though cannabis remains illegal under federal law, various states have been legalizing it for serious health conditions—which they refer to as the “qualifying conditions.” Cancer is one of those conditions. . Medical cannabis has the potential to positively impact multiple facets of the lives of patients with cancer, however the greatest benefit is currently seen in chemotherapy-associated nausea and vomiting.
As mentioned above, nausea and vomiting are common side effects of numerous chemotherapeutic agents. Two large reviews found that cannabinoid therapies are not only more effective than placebo, but that they even outpace some traditional therapies [4-5]. One such study demonstrated that dronabinol, a cannabis-derived product, was associated with greater improvements in nausea intensity and episodes of vomiting/retching than ondansetron (Zofran).  Additionally, multiple studies have found that patients prefer cannabis-derived products for treatment of nausea and vomiting over other, more traditional, medications. Currently available products that are FDA approved for this condition include Dronabinol and Nabilone.
Neuropathic pain is another side effect of many chemotherapy agents. Although the data is not as strong as it is for nausea and vomiting, cannabis products have demonstrated benefits for the control of neuropathic pain. Although more studies need to be performed in specific patient populations, it would not be unreasonable to trial a cannabis therapy in a patient with neuropathic pain, especially those resistant to opioid and other traditional medications. 
For all medications, it is just as important to avoid harm as it is to provide benefit. A concern with cannabis has been that given it may be an inhaled or orally administered product, does it increase the risk of oral, throat, and lung cancer in the same way that tobacco products do? Fortunately, research to date suggests that cannabis-derived products do not result in increased rates of oral, throat, or lung cancers. 
Although anecdotal evidence suggests that cannabis may be able to stimulate appetite and support weight gain in patients with cancer, current research is equivocal as to whether this is the case. More details studies are needed to understand this relationship better. 
More interesting though, it the potentially impact cannabis may have on the growth and development of cancer itself. There is evidence that cannabis-based products can slow or halt the growth of multiple types of cancer. The most clinically relevant data shows that cannabinoids can impact the growth of gliomas, a type of brain tumor.  Positive effects have been found in experiments in other cancer types, including: breast cancer , gastrointestinal cancer , and prostate cancer . Cannabinoid receptor expression has also been shown to correlate with prognosis in hepatocellular carcinoma (a type of liver cancer). 
This information is not meant to suggest that patients use cannabis products as a substitute for traditional therapies. Rather, it is meant to provide hope that future research can harness the natural cannabinoid system of the body to provide positive impacts for cancer patients and improve survival.
Cannabinoid receptors are found in every organ system throughout the body and are involved in numerous function. The greatest benefit cannabis-based products can currently provide to patients with cancer is by improving symptoms of nausea and vomiting associated with cancer and its treatments. However, it is hopeful that future research will show that more advanced cannabinoid products can provide other benefits, and potentially even be used to treat the cancer itself.
- Bridgeman MB, Abazia DT. Medicinal Cannabis: History, Pharmacology, And Implications for the Acute Care Setting. Pharmacy and Therapeutics. 2017;42(3):180-188.
- Whiting PF, et al. Cannabinoids for Medical Use: A Systematic Review and Meta-analysis. Jama. 2015. 313(24): 2456-2473.
- Smith LA, Azariah F, Lavender VT, Stoner NS, Bettiol S. Cannabinoids for nausea and vomiting in adults with cancer receiving chemotherapy. Cochrance Database Syst Rev. 2015. 11: 1465-1858
- Meiri E, Jhangiani H, Vredenburgh JJ, Barbato LM, Carer FJ, Yang HM, Baranowski V. Efficacy of dronabinol alone and in combination with ondansetron versus ondansetron alone for delayed chemotherapy-induced nausea and vomiting. Curr Med Res Opin. 2007. 23(3): 533-43.
- Mucke M, Phillips T, Radbrucnh L, Petzke F, Hauser W. Cannabis-based medicines for chronic neuropathic pain in adults. Cochrance Database Syst Rev. 2018.
- Strasser F, et al. Comparison of Orally Administered Cannabis Extract and Delta-9-Tetrahydrocannabinol in Treating Patients With Cancer-Related Anorexia-Cachexia Syndrome: A Multicenter, Phase III, Randomized, Double-Blind, Placebo-Controlled Clinical Trial From the Cannabis-In- Cachexia-Study-Group. Journal of Clinical Oncology. 24(21): 3394-3400.
- Tashkin DP. Effects of Marijuana Smoking on the Lung. Ann Am Thorac. 10(3): 239-247.
- Rocha FC, Dos Santos Junior JG, Stefano FC, da Silveria DX. Systematic review of the literature on clinical and experimental trials on the antitumor effects of cannabinoids in gliomas. J Neuroocol. 2014. 116(1): 11-24.
- Grimaldi C, et al. Anandamide inhibits adhesion and migration of breast cancer cells. Experimental Cell Research. 2006. 312: 363-373.
- Izzo AA, Camilleri M. Cannabinoids in intestinal inflammation and cancer. Pharmacological Resarch. 2009. 60:117-125.
- Sarfaraz S, et al. Cannabinoid Receptor as a Novel Target for the Treatment of Prostate Cancer. Cancer Res. 2005. 65(5): 1635-1641.
- Xu X, et al. Overexpression of cannabinoid receptors CB1 and CB2 correlates with improved prognosis of patients with hepatocellular carcinoma. Cancer Genetics and Cytogenetics. 2006. 171: 31-38.