As a first-line treatment for cancer, chemotherapy saves the lives of countless patients who wouldn’t otherwise survive their illnesses. At the same time, it is one of the most feared treatments in medicine due to its destructive and wide-ranging side effects. Indeed, despite substantial advancements in chemotherapeutic regimes, chemotherapy overwhelmingly remains difficult for patients to tolerate.
Nearly all patients who receive chemotherapy experience side effects whether or not they derive a large therapeutic benefit. These side effects and their intensity may differ slightly depending on the chemotherapeutic agent, but typically include:
- Hair loss
- Neuropathic pain
- Cognitive dysfunction
- Immune suppression
Such effects often begin with the administration of chemotherapy and slowly taper with its cessation, but some patients struggle with the side effects of chemotherapy for years after the therapy has concluded. Unfortunately, the medications typically prescribed to address these effects may not provide adequate relief and can carry a broad spectrum of side effects on their own.
Due to the disruptive and even dangerous nature of chemotherapy, patients would greatly benefit from a well-tolerated adjunct therapy that will make them more comfortable and help them to recover. Ideally, this therapy could be administered immediately after a dose of chemotherapy without interfering with the therapeutic effects while also being suitable for long-term use by those who struggle with persistent effects after completion of treatment. A growing body of literature now suggests that cannabidiol (CBD) may be that therapy. By using CBD after chemotherapy, patients may finally have access to the chemotherapy adjunct they need.
Reducing Pain and Potentiating Chemotherapy
Neuropathic pain is one of the primary and most troubling effects of chemotherapy, affecting up to 75% of patients. This pain results from chemotherapy’s infliction of systemic cellular damage that causes nerve cells to die or experience dysfunction. Patients with neuropathic pain may be treated with a broad range of drugs, including anti-epileptics, such as gabapentin and pregabalin, and antidepressants, specifically tricyclic antidepressants (TCAs) and selective serotonin norepinephrine inhibitors (SNRIs). However, these can cause significant side effects in some patients and may be of limited efficacy. Meanwhile, those with more severe pain often rely on opioid painkillers to ease discomfort. Unfortunately, opioids carry a number of serious risks, potentially impairing cognitive and gastrointestinal function, causing mood changes, and presenting risk of addiction and overdose, particularly if taken long-term. Opioids may at times be augmented by the use of NSAIDs, but NSAIDs on their own have not been shown to be effective for neuropathic pain and may cause renal, cardiovascular, and gastrointestinal damage, particularly with extended use.
In light the limitations of conventional treatments for chemotherapy-induced neuropathic pain, many are now looking to CBD to complement or serve as an alternative to other forms of pain relief. Unlike standard treatments, CBD is not only known for its efficacy, but for its mild side-effect profile and suitability for both short and long-term use. Because CBD can safely be used alone or in concert with other pain relievers, patients may achieve more complete pain relief, decrease dosage and/or frequency of other analgesics, or eliminate use of other analgesics altogether. Additionally, research suggests that CBD may work synergistically with chemotherapy drugs themselves.
A 2014 study using mouse models found that CBD could reduce neuropathic pain while simultaneously potentiating chemotherapy drugs when co-administered. In the study, healthy mice were given a placebo or a round of chemotherapy three times a week for ten weeks. Of the mice who were given chemotherapy, half were also given CBD at the same time. The chemotherapy reliably caused the mice to become sensitive to otherwise mild stimuli and react as though they were in pain to normal-intensity stimuli. The CBD treatment group, however, exhibited a significantly different pain threshold; they responded as though they were in pain only when exposed to a mechanical pressure of 1.5 grams. This was a massive improvement over the mice who did not receive CBD, who exhibited pain after a pressure of 0.5 grams. In comparison, mice that didn’t get the chemotherapy treatment or CBD exhibited pain after slightly over a gram of pressure, meaning that CBD is capable of reducing pain beyond healthy baseline levels of sensation. These effects persisted in between doses of CBD but at lower intensities. This indicates that taking CBD after chemotherapy might be nearly as effective to minimize side effects as administration at the time of treatment. Excitingly, researchers also found that far smaller doses of the chemotherapy drug were needed in the mice that were dosed with CBD; simultaneous administration of CBD potentiated the chemotherapy agent, allowing the treatment to maintain the same level of efficacy even when the dose was reduced by 50%.
CBD’s analgesic effects after chemotherapy have also been confirmed in a placebo-controlled clinical trial of 303 patients with treatment-resistant post-chemotherapy pain. In the trial, 30% of patients responded to a nasal spray therapeutic containing CBD. While 30% may seem underwhelming, it’s important to note that the patients in the study were only eligible for inclusion if both first and second-line analgesics like NSAIDs and opioids had failed to curb their pain, which may or may not have been neuropathic in origin. The patients who responded to CBD experienced a 0.99 point reduction in their pain according to the 10-point Pain Numerical Rating Scale (NRS) used in the study. In contrast, patients who received placebo reported a 1.78-point increase in pain, indicating that CBD had a large impact. For responders, pain relief started promptly after administration of the CBD nasal spray and continued for the duration of the study’s 15-week period. Significantly, CBD treatment also helped the patients find relief from pain-associated symptoms like insomnia and malaise; the patients who responded to CBD reported subjective improvements in their quality of sleep which they directly attributed to CBD rather than other factors like time spent in recovery from chemo. No patients exhibited accumulating tolerance to the CBD therapy, nor did any patients exhibit signs of dependence or subsequent withdrawal.
The results of these studies indicate that CBD is a potent adjuvant to chemotherapy for the purposes of patient comfort, ultimately improving overall quality of life in multiple ways. CBD also has few side effects of its own and is not known to interfere with other cancer-related treatments, allowing patients to easily integrate CBD within a comprehensive treatment plan. Although CBD hasn’t been directly linked to improved rates of survival or cancer remission, few clinicians would dispute the idea that more rested and less distressed patients tend to experience faster recovery. Indeed, with the help of their doctors and CBD, patients may be able to increase the potency of their chemotherapy treatment and subsequently use lower doses of chemotherapy, potentially diminishing incidence and severity of chemo-associated pain, cognitive dysfunction, and other side effects.
CBD After Chemotherapy Can Address Hair Loss and Inflammation
Controlling pain is a major care priority for chemotherapy patients, but typically other side effects are problematic as well. The systemic inflammation and gastrointestinal malfunctions associated with chemotherapy can produce physiological discomfort as well as adding a significant burden to psychological health. Among the many chemotherapy side effects which tend to fray the mental health of patients, hair loss is perhaps the most common.
Hair loss is one of the most stereotypical symptoms of chemotherapy, affecting 65% of patients. At present, CBD may be the only therapeutic which has been confirmed to help patients to recover their hair. In mice given a course of chemotherapy, researchers found that without any aid, the mice lost hair for 10 days at the start of chemotherapy, then slowly started to regrow their hair after 21 days had elapsed from the last dose. A subset of these mice were given a compound containing CBD and thyroid hormones two days after a round of chemotherapy. The CBD-treated mice still lost their hair as a result of chemotherapy, but hair regrowth started immediately after chemotherapy ceased rather than experiencing a delay. The net result was that the mice given the compound containing CBD reached normal levels of hair nearly a month faster than the other mice. This means that CBD can potentially reduce the psychological damage of chemotherapy-induced hair loss by helping patients recover from it much faster.
Faster hair regrowth doesn’t occur in a vacuum, however. CBD has no independent ability to cause hair to grow in healthy subjects. Instead, CBD can reduce post-chemo inflammation that often harangues patients, a factor which may contribute toward both its analgesic properties and its ability to help superficial tissues like the scalp return to their normal functioning. By curbing inflammation, CBD can thus counteract the destruction that chemotherapy tends to cause to superficial tissues and mucosal surfaces, meaning that patients who take CBD may experience faster nail, skin, and bowel tissue regrowth as well.
Of course, the consequences of post-chemo inflammation are not confined to superficial tissues and mucosal surfaces. Rather, this systemic inflammation likely contributes to the severity of nearly all chemotherapy side effects by prevention normal tissue function. As a result, the corresponding organs can’t perform as effectively as they would when free of inflammation. Processes ranging from blood detoxification to contraction of cardiac muscle start to fall behind, an effect which can often cascade to problems elsewhere in the body. In heart tissue, chemotherapy’s inflammation can be especially dangerous.
Most chemotherapeutic agents are overtly cardiotoxic. However, CBD can attenuate the cardiotoxic effects of some chemotherapy agents by reducing inflammation and inducing protective chemical signaling molecules like survivin in cardiac tissue; while supporting cardiac cell survival, CBD also helps cells clear toxins and prevents inflammation as well as cell death. While the impact on patients’ quality of life in the wake of CBD’s cardioprotective effects is unclear, patients may find that they are much more comfortable as a result of the anti-inflammatory effects of CBD alone.
The Future Of CBD Therapeutics
Research into CBD’s plethora of benefits is ongoing, but there is presently an abundance of evidence that supports the use of CBD after chemotherapy for the purpose of reducing chemo side-effects. Given the life-changing impact that CBD can have on the lives of chemotherapy patients, many are already adopting its use. Patients are perhaps the largest group driving CBD’s popularization, frequently picking up CBD on their own and working on conjunction with their practitioner to find how it can help them the most. While many questions remain to be answered about the best ways to maximize CBD’s therapeutic impact in conjunction with chemotherapy, clinicians and patients can start using CBD immediately with the help of products already on the market. For those are interested in integrating CBD in their treatment plan, a highly palatable supplement which can be consumed directly as a liquid or added into food may be the best choice to enhance treatment.
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Fouad AA, Albuali WH, Al-Mulhim AS, Jresat I. 2013. Cardioprotective effect of cannabidiol in rats exposed to doxorubicin toxicity. Environmental Toxicology Pharmacology. 36(2):347-357. https://www.ncbi.nlm.nih.gov/pubmed/23721741
Katikaneni R, Ponnapakkam T, Seymour A, Sakon J, and Gensure R. 2014. Parathyroid hormone linked to a collagen binding domain (PTH-CBD) promotes hair growth in a mouse model of chemotherapy-induced alopecia in a dose-dependent manner. Anticancer Drugs. 25(7):819-825. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4520809/
Serpell M, Ratcliffe S, Horkova J, Schofield M, Taylor L, et al. 2014. A double-blind, randomized, placebo-controlled, parallel group study of THC/CBD spray in peripheral neuropathic pain treatment. European Journal of Pain. 18(7):999-1012. https://www.ncbi.nlm.nih.gov/pubmed/24420962
Ward SJ, McAllister SD, Kawamura R, Murase R, Neelakantan, et al. 2014. Cannabidiol inhibits paclitaxel-induced neuropathic pain through 5-HT1A receptors without diminishing nervous system function or chemotherapy efficacy. British Journal of Pharmacology. 171(3):636-645. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3969077/