CBD for cancer

What potential mechanisms of action of CBD are relevant for the inhibition of tumor growth?

CBD primarily affects tumor cells through the following approaches, which can inhibit tumor growth:

• Increase of reactive oxygen species (ROS): This imbalance often leads to DNA damage and apoptosis. Due to the increased formation of these "free radicals," the genetic material and other vital structures in tumor cells are damaged. As a result of such damage, the affected cells often initiate a self-destruction program (apoptosis).
• Induction of ER stress: Misfolded proteins trigger the so-called UPR (unfolded protein response), which under certain conditions leads to cell death. The endoplasmic reticulum (ER) is responsible for the proper folding of proteins. If too many faulty proteins accumulate there, a stress reaction (UPR) occurs, which – if it becomes excessive – leads to cell death. CBD can enhance this overload in tumor cells.
• Immunomodulation: CBD can alter the tumor environment so that tumor cells are more easily attacked by immune cells (e.g., via ICAM-1). CBD can affect the tissue around the tumor ("tumor microenvironment") so that defense cells (e.g., certain lymphocytes) act more effectively against the cancer cells. One example is the upregulation of the molecule ICAM-1, which makes tumor cells more "visible" to attacking cells.
• Influence on signaling pathways: By binding to receptors (CB1, CB2, TRPV1/2, PPARγ), growth-promoting pathways (e.g., AKT/mTOR, MAPK) are inhibited. Cancer cells often "overdrive" their signaling mechanisms to multiply rapidly. CBD can bind to specific receptors (e.g., CB1/CB2, TRPV1/2, PPARγ) and thereby throttle the overactive metabolic pathways – such as AKT/mTOR or MAPK. This slows down growth.
• Inhibition of migration and invasion: Among other things, metastasis is inhibited by the upregulation of TIMP-1 and blockade of proteolytic enzymes. To spread to other body regions, tumor cells use enzymes and mechanisms that break down surrounding tissue. CBD increases TIMP-1, an inhibitor of such enzymes. This makes cell migration and invasion more difficult and inhibits metastasis formation.

How does CBD differ in its effects from other cannabinoids like THC in the context of cancer therapy?

Compared to THC, which acts mainly via the CB1 receptor and can trigger psychotropic effects, CBD exerts its anti-cancer effects without causing an intoxication-like state. THC focuses more on CB1/CB2 and is limited by its psychoactive component at higher doses. CBD, on the other hand, has a comparatively low affinity for CB1/CB2 and can influence various tumor cell mechanisms (e.g., ROS formation, ER stress) without causing the same side effects. Thus, CBD is generally better tolerated in cancer therapy and causes fewer central nervous system effects than THC.

CBD differs from THC mainly in the way it acts on the receptors of the endocannabinoid system and the resulting effects:

Psychoactivity

• THC binds with high affinity to the CB1 receptor, which can lead to psychotropic effects (intoxication). This psychoactive component limits its therapeutic use at higher doses.
• CBD on the other hand, has only a low affinity for CB1/CB2 and does not cause intoxication. This often makes higher dosing better tolerated.

Mechanistic diversity

• CBD acts on multiple target structures (e.g., TRPV1/2, PPARγ) and thus influences central processes of the tumor cell such as increased cellular stress (ROS, ER stress) or migratory ability (e.g., through TIMP-1 upregulation).
• THC acts mainly through the classical cannabinoid receptors CB1 and CB2. Although THC also shows anti-cancer activity, the dose limitation due to its psychotropic effects comes more into focus.

Therapeutic implications

• CBD is often described as better tolerated because it has fewer central nervous system side effects. It can also support the effect of conventional therapies (e.g., chemotherapeutics) without patients having to expect the typical intoxication effects. 
• THC can also promote anti-tumor processes at lower doses, such as inhibiting tumor growth. However, the simultaneous psychoactive effect requires more precise dose adjustment.

CBD is considered a non-intoxicating component of the cannabis plant that triggers multiple mechanisms against tumor cells while minimizing the side effects that occur with THCcan occur with preparations containing - in higher doses.

What study results are currently available that indicate a direct anti-cancer effect of CBD?

Evidence base

Preclinical evidence (cell culture and animal models)

• Broad spectrum of tumor types (glioblastoma, breast, lung, prostate cancer, colon carcinoma, leukemias) were investigated. In all cases, it was found in vitro a significant inhibition of cell proliferation, induction of apoptosis, and partly reduction of metastasis (e.g., via upregulation of ICAM-1, TIMP-1).
• Synergies with chemotherapeutics: Particularly emphasized are the positive combination effects of CBD with gemcitabine (pancreatic carcinoma), doxorubicin (including breast and liver cancer cells), cisplatin (e.g., head/neck tumors, lung cancer), oxaliplatin (colon cancer), and temozolomide (glioblastoma). In animal models, such CBD+chemo combinations often improved therapy response and reduced resistance.
• Mechanisms: The antitumor effects are mainly explained by increased ROS generation, endoplasmic reticulum stress, inhibition of growth-promoting signaling pathways (AKT/mTOR, MAPK), and immunomodulation (e.g., better recognition of tumor cells by defense cells).

Small clinical studies and case reports

• Glioblastoma: A pilot study (CBD/THC spray in addition to temozolomide) showed possible survival benefits, although the final publications are still pending. Individual case observations also suggest that high-grade brain tumors may progress more slowly or remain stable under CBD administration.
• Pancreatic and breast cancer: Experience reports and animal experiments suggest sensitization to standard therapies, but larger clinical studies are lacking here.
• Lung carcinoma: A case report describes tumor regression with exclusive intake of CBD oil. Whether this is causally attributable to CBD can only be assessed to a limited extent; nevertheless, it shows that initial clinical indications are present.

Overall assessment

The majority of results come from in vitro‑ or in vivo-studies with solid methodology but still limited transferability to humans.
Clinical data are – apart from a few small studies and case series – not yet extensive enough to make a definitive recommendation for CBD as a sole cancer therapy. However, the existing evidence is promising: They support the idea that CBD not only has tumor-inhibiting properties but can often achieve higher efficacy or lower resistance in combination with classical therapies (chemotherapy, radiation). All the studies discussed here provide clear preclinical evidence for the direct anticancer activity of CBD. Initial small studies and case reports also suggest that it could have positive effects in humans. However, broad clinical application still requires large-scale, controlled studies to clearly determine dosage, efficacy, and long-term tolerability.

To what extent can CBD, as a supportive measure, enhance or complement the effectiveness of conventional cancer therapies (e.g., chemotherapy, radiation)?

Improved response rate and reduced resistance formation

• Glioblastoma: In in vitro- and in vivoIn models (e.g., U87MG, T98G), CBD combined with temozolomide (TMZ) significantly enhanced growth inhibition compared to TMZ alone. An initial pilot study on oromucosal CBD/THC spray + TMZ suggests prolonged survival times.
• Pancreatic Carcinoma: In mice, gemcitabine combined with CBD showed significantly better results (longer survival); CBD appears to reduce resistance and increases the sensitivity of cancer cells.
• Colorectal Cancer: CBD can enhance oxaliplatin and 5-FU (FOLFOX), among other things by increasing oxidative stress and blocking resistance mechanisms.

Reduction of Side Effects

• Pain and Neuropathies: Some studies show that CBD can alleviate therapy-induced nerve damage (e.g., from paclitaxel) without diminishing the antitumor effect of the cytostatic drug.
• Nausea and Vomiting: Similar to THC, CBD can reduce chemo-induced nausea, but without psychoactive side effects.

Possible Organ and Neuroprotection

• Heart & Kidneys: Tier models suggest that CBD may protect against doxorubicin-induced cardiotoxicity or cisplatin-related kidney damage.
• Nervous system: CBD can exert neuroprotective properties, which could mitigate some side effects of chemo- and radiotherapies (e.g., cognitive impairments).

Mechanisms of synergy

• Increase of oxidative stress: By enhancing ROS, CBD makes tumor cells more susceptible to DNA damage; chemotherapeutics or radiation then encounter already "pre-stressed" cells.
• Blockade of growth-promoting signaling pathways: CBD inhibits, among others, AKT/mTOR, NF-κB, and MAPK, which gives conventional therapies more "punch."
• Promotion of the immune response: A changed tumor microenvironment can increase the effectiveness of certain therapies (e.g., radiotherapy) because CBD upregulates ICAM-1 and keeps immune cells active.

Limitations and open questions

• Immunotherapies: Data are partly contradictory. Individual observations suggest possible interactions that could affect the efficacy of checkpoint inhibitors. Clear recommendations are missing.
• Dosage and interactions: Standardized protocols on how much CBD in which formulation should be given together with which chemotherapy are still lacking.
• Lack of large clinical studies: Although there are initial promising pilot projects and case series, robust RCTs are needed for widespread use.

Overall, numerous preclinical findings and initial clinical indications suggest that CBD can support conventional cancer therapies and mitigate their side effects. The specific benefits (e.g., extended survival time, reduced resistances) are most clearly demonstrated in glioblastoma, pancreatic, and colon cancer models. However, a conclusive evaluation in larger, controlled studies is still pending.

What advantages and risks does the combined use of CBD and traditional cancer medications entail regarding effectiveness and side effects?

Advantages

Better effectiveness (synergy effects)

• Inhibition of resistances: In models for pancreatic cancer (CBD + Gemcitabine) and colon cancer (CBD + Oxaliplatin), CBD was able to reduce resistances and increase the effectiveness of chemotherapy.
• Enhanced tumor cell damage: CBD partly increases oxidative stress (ROS), making tumor cells additionally vulnerable – conventional cytostatics then encounter already weakened cells.
• Improved tolerability: Studies suggest that CBD can reduce neuro- and organ-toxic effects of some cytostatics (e.g., Paclitaxel, Cisplatin, Doxorubicin) without worsening therapy success.

Reduced side effects

• Relief of nausea and vomiting: CBD can combat chemo-induced nausea, similar to THC, but without strong psychotropic effects.
• Pain relief: In chemo- or tumor pain-related neuralgia, CBD-containing preparations can additionally exert an analgesic effect.

Risks

Possible interactions

• Cytochrome P450 inhibition: CBD can inhibit certain enzymes (e.g., CYP2C9, CYP2D6) involved in the breakdown of cancer drugs; this could unexpectedly alter their plasma levels.
• Unclear effects on immunotherapies: Some indications suggest a possible weakening of the immune response (e.g., with checkpoint inhibitors); however, solid studies are missing.

• Dosage uncertainty
  

  • Lack of standardized protocols: Neither the optimal amount of CBD (pure form or full spectrum) nor the timing in relation to chemo-/radiotherapy are reliably established. Too much CBD could, for example, enhance interactions, while too little shows no effect.
    

• Insufficient clinical data
  

  • Large RCTs needed: Although many advantages have been documented preclinically, comprehensive controlled studies on combination therapy are still lacking. This complicates clear therapy recommendations.

The combination of CBD and classical oncological drugs primarily offers the potential for better efficacy and fewer side effects but carries the risk of pharmacokinetic interactions and still unresolved interactions. The results of previous studies are promising, but a definitive assessment requires further large-scale clinical trials.

How does CBD affect the immune system and the tumor-associated inflammation that plays an important role in the development and progression of cancer?

Activities

Alteration of the Tumor Microenvironment

• CBD can increase the expression of certain molecules such as ICAM-1. This cell adhesion molecule facilitates the recognition and destruction of tumor cells by the body's defense cells (e.g., lymphokine-activated killer cells).

Activation or Sensitization of Immune Cells

• Some findings suggest that CBD supports the function of effector immune cells (such as T cells, macrophages) by modifying proinflammatory or immunosuppressive factors in the tumor environment. This strengthens the body's natural cancer defense.

Reduction of Harmful Inflammatory Mechanisms

• Tumor cells use certain inflammatory processes to grow and suppress immune reactions. CBD can act here— for example, by blocking or attenuating signaling pathways such as NF-κB— thereby dampening these processes so that the immune system can more effectively attack the tumor.

Inhibition of Immune Resistance Strategies

• In some types of cancer, an increase in regulatory T cells or myeloid-derived suppressor cells (MDSC) is observed, which block the immune response to the tumor. According to preclinical data, CBD could reduce this effect by modulating signaling pathways that attract or activate these immunosuppressive cells.

Synergies and Open Questions

• Initial indications show that CBD, in combination with radiotherapy or chemotherapy, can further support the local immune system and thus enhance the antitumor effect.
• At the same time, there is uncertainty about how CBD interacts with newer immunotherapies (e.g., checkpoint inhibitors), as it can also downregulate inflammatory processes. Currently, there is a lack of reliable clinical data in this area.

CBD can activate the immune system against tumor cells and influence tumor-associated inflammation in such a way that the tumor is less able to "escape immune detection." This immunomodulatory effect may complement conventional oncological therapies but remains the subject of intensive research.

Which dosage and administration forms of CBD have proven to be particularly effective or safe in current studies?

From the studies and case reports discussed here, it emerges that so far no uniformly recommended standard dosage for CBD. Nevertheless, some trends and practical approaches can be identified:

Dosage Range

• Studies on Glioblastoma and Breast Cancer: Doses between 100 and 400 mg/day (oral) were observed in some patients, leading to clinically relevant effects. Oral doses up to 600 mg/day have been documented in case reports, though with considerable individual variation. Pilot studies with oromucosal sprays (e.g., CBD/THC 1:1) indicate that even relatively low CBD amounts (a few mg per spray over the day) can show effects, especially in combination with other cannabinoids.

Dosage forms

• Oils/tinctures (Sublingual/Oral): Widely used and most frequently documented in case reports. Patients dose in milliliter increments, with the exact CBD content varying from product to product.
• Capsules/tablets: Allow for more consistent dosing but are less frequently found in studies and are not uniformly standardized.
• Oromucosal sprays: Used especially in combination with THC (e.g., in glioblastoma pilot studies). Advantage: relatively consistent drug uptake and better dose control.
• Full-spectrum vs. isolate products: Preclinical studies especially suggest that full-spectrum CBD ("entourage effect") might have partially better efficacy than pure isolate. However, clinical evidence is largely lacking.

Tolerability and safety

• Generally well tolerated: Most patients show only mild side effects (e.g., fatigue, dry mouth, occasional nausea).
• Interactions: High doses can inhibit cytochrome P450 enzymes, which alters plasma levels of other medications. This is especially important to consider in patients undergoing chemotherapy.

Although case series and smaller studies suggest a a wide range from 50 mg up to several hundred milligrams There is no fixed scheme for all cancer types, although daily references exist. The choice of dosage and form of administration is usually an individual decision, depending on tolerability, product availability, and accompanying therapies. Larger, standardized studies would be necessary to clearly define optimal amounts and forms of administration.

How can CANNEFF CBD suppositories alleviate the side effects of cancer therapy?

In many cancer therapies – especially chemotherapy and radiation – not only tumor cells but also healthy cells, such as those of the mucous membranes, are attacked. Since these mucosal cells have a high rate of division, they are particularly susceptible to the toxic effects of the treatment. Damage to the mucous membranes leads to inflammation, pain, dryness, and impaired wound healing, which is observed, for example, in oral or vaginal mucositis symptoms. These side effects can significantly affect the well-being of patients and represent an important therapeutic aspect that supportive measures like CANNEFF VAG SUP are specifically intended to address.

CANNEFF VAG SUP Vaginal Suppositories combine 100 mg cannabidiol (CBD) and sodium hyaluronate in a patented emulsion matrix. This innovative formulation ensures rapid and complete delivery of both active ingredients, optimizing local absorption and minimizing systemic effects. CANNEFF unfolds its antioxidant and anti-inflammatory properties, contributing to the neutralization of reactive oxygen species (ROS) and stabilization of the redox balance. At the same time, hyaluronic acid supports the moisture supply of the vaginal mucosa, promotes tissue regeneration, and alleviates symptoms such as vaginal dryness, pain during intercourse, vaginal inflammations, as well as complaints that may occur during chemotherapy and hormonal treatment. The targeted local application via suppositories leads to a rapid effect (within about 60 minutes) and thus enables effective relief of therapy-related side effects, making CANNEFF VAG SUP a promising component of an integrative oncological care concept.

Sources

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