17.4 Complementary, Alternative & Integrative Therapies in Oncology
Key Takeaways
- Up to 30-50% of patients with cancer use complementary approaches, usually without disclosing them; nonjudgmental supplement histories are a mandatory part of oncology medication reconciliation.
- St. John's Wort potently induces CYP3A4 and P-glycoprotein, cutting exposure to oral oncolytics (imatinib, venetoclax, CDK4/6 inhibitors, irinotecan) and must be stopped with a washout before therapy; grapefruit inhibits CYP3A4 and raises TKI toxicity risk.
- High-dose antioxidant supplements (vitamins C, E, beta-carotene) are discouraged during radiation and ROS-dependent chemotherapy because ROS scavenging can antagonize treatment; SELECT and CARET linked vitamin E and beta-carotene supplements to increased cancer risk.
- ASCO-SIO integrative oncology guidelines support acupuncture/acupressure, mindfulness, massage, and music therapy as adjuncts for CINV, pain, anxiety, and fatigue; ginger, cannabinoids, and acetyl-L-carnitine must not replace guideline-directed antiemetic or neuropathy care.
- Substituting alternative therapy for curative treatment approximately doubles cancer mortality; pharmacists counsel with authoritative resources (NCI PDQ, MSKCC About Herbs, NCCIH) and document every supplement decision.
1. Definitions, Prevalence & the Disclosure Gap
Blueprint task 2B7 (Complementary and Alternative Therapies) expects the oncology pharmacist to manage patients who use non-conventional therapies safely and without judgment. Complementary therapies are used alongside conventional treatment (e.g., acupuncture for nausea); alternative therapies are used instead of it; integrative oncology coordinates evidence-informed complementary modalities with conventional care. Surveys consistently show 30-50% of patients with cancer use some form of complementary approach, and the majority do not spontaneously disclose it to their oncology team — often because they fear disapproval. Every oncology medication reconciliation must therefore explicitly probe for vitamins, minerals, herbs, teas, and "natural" products.
2. Pharmacokinetic & Pharmacodynamic Interactions (High-Yield Table)
| Product | Mechanism | Clinical Consequence | Action |
|---|---|---|---|
| St. John's Wort | Potent CYP3A4 / CYP2C19 / P-glycoprotein inducer | Slashes exposure to imatinib, venetoclax, CDK4/6 inhibitors, irinotecan (SN-38 AUC down ~40%), docetaxel -> subtherapeutic treatment failure | Discontinue (allow ~2-week washout) before oral oncolytics |
| Grapefruit / Seville orange / pomelo | Intestinal CYP3A4 inhibition | Raises exposure to many TKIs and oral agents -> toxicity | Avoid during therapy with narrow-index CYP3A4 substrates |
| Green tea extract (EGCG) | Catechin binds the boronic acid of bortezomib (in vitro) | May antagonize proteasome inhibitor activity | Discourage concentrated extracts during bortezomib; dietary tea in moderation is acceptable |
| High-dose biotin | Interferes with streptavidin-biotin immunoassays | Falsely LOW troponin/PSA/beta-hCG; falsely high free T4 -> misinterpreted monitoring and emergencies | Hold >=48-72 hours before laboratory draws |
| Garlic, ginkgo, high-dose fish oil, curcumin | Antiplatelet / anticoagulant potentiation | Bleeding risk with surgery, thrombocytopenia, or anticoagulation | Stop before procedures and during severe thrombocytopenia |
| Milk thistle (silymarin) | Weak CYP2C9/3A4 modulation | Minor interaction potential; generally tolerated | Monitor; document |
| Echinacea / "immune boosters" | Immunostimulation | Theoretical antagonism of immunosuppression; caution around checkpoint-inhibitor irAE management | Counsel on uncertainty; document |
| Kava, comfrey | Direct hepatotoxicity | Additive liver injury with hepatotoxic regimens | Avoid |
3. Antioxidants, Phytoestrogens & Treatment-Antagonism Controversies
- High-dose antioxidant supplements (vitamins C and E, beta-carotene, N-acetylcysteine) are discouraged during radiation therapy and ROS-dependent cytotoxic regimens (anthracyclines, platinums, alkylators) because reactive-oxygen-species scavenging may blunt treatment mechanisms; the SELECT trial linked vitamin E supplementation to increased prostate cancer risk, and CARET linked beta-carotene to increased lung cancer in smokers.
- Soy/phytoestrogens in ER-positive breast cancer: moderate dietary intake appears safe and possibly beneficial; concentrated isoflavone supplements should be discouraged pending better data.
- Laetrile ("vitamin B17") is ineffective and causes cyanide toxicity; high-dose IV vitamin C has no proven survival benefit and risks oxalate nephropathy and G6PD hemolysis; mistletoe extracts lack rigorous efficacy evidence and interact unpredictably.
- "Alternative instead of curative" harm: observational data show patients who substitute alternative medicine for conventional curative cancer treatment have roughly double the risk of death; the pharmacist's role is respectful redirection, never ridicule.
A 61-year-old patient with chronic-phase CML achieving a deep molecular response on imatinib 400 mg daily reports starting St. John's Wort 300 mg three times daily last month for low mood. Quantitative BCR::ABL1 transcripts have risen from 0.02% to 0.9% (IS). What is the most likely pharmacologic explanation and appropriate action?
4. Evidence-Supported Integrative Modalities (ASCO-SIO Guidelines)
The joint ASCO-Society for Integrative Oncology guidelines distinguish helpful adjuncts from unsupported substitutes:
- Recommended adjuncts: acupuncture and acupressure (chemotherapy-induced nausea/vomiting adjunct, cancer pain, hot flashes, xerostomia), mindfulness/yoga (anxiety, depression, fatigue), massage therapy (anxiety, pain — gentle technique, avoid tumor sites and lymphedema limbs), music therapy, hypnosis (procedural pain and anxiety).
- Insufficient or negative evidence: ginger is not a substitute for guideline antiemetic prophylaxis (5-HT3 + NK1 + dexamethasone +/- olanzapine); acetyl-L-carnitine should be avoided for chemotherapy-induced peripheral neuropathy (worsened neuropathy in a randomized trial); oral glutamine evidence is inconsistent.
5. Cannabis & Cannabinoids
- Dronabinol and nabilone are FDA-approved for refractory chemotherapy-induced nausea and vomiting — they are rescue agents, not replacements for first-line prophylaxis.
- Cannabidiol (CBD) is metabolized by and inhibits CYP2C19 and CYP3A4 (drug interactions with TKIs and other narrow-index agents), causes transaminase elevations (especially with valproate and hepatotoxic drugs), and product content varies widely because supplements are not FDA pre-approved.
- There is no evidence that cannabis or concentrated cannabinoid oils treat cancer; counsel patients away from substituting them for systemic therapy.
6. Pharmacist Counseling Framework & Resources
- Ask without judgment — a structured supplement history belongs in every medication reconciliation, including teas, tinctures, and family remedies.
- Check the interaction first against the specific antineoplastic regimen (CYP3A4 substrates, QTc-prolonging agents, hepatotoxins, narrow-therapeutic-index oral oncolytics).
- Use authoritative references: NCI PDQ Integrative, Alternative, and Complementary Therapies summaries; Memorial Sloan Kettering "About Herbs" database/app; NIH National Center for Complementary and Integrative Health (NCCIH).
- Respect the regulatory reality: under DSHEA (1994), dietary supplements are not FDA pre-approved for safety or efficacy; recommend third-party-verified products (USP or NSF seals) when a patient elects to continue one.
- Document and coordinate — record the product, dose, and decision in the chart and loop in the prescriber; escalate any plan to replace curative therapy to the full care team immediately.
A patient receiving highly emetogenic cisplatin-based chemotherapy asks to replace the prescribed antiemetic regimen with "natural remedies" and asks which complementary approach has guideline-level evidence as an adjunct for chemotherapy-induced nausea. Which response is correct?
A 54-year-old patient starting definitive cisplatin plus radiation for locally advanced head and neck cancer asks about continuing her daily high-dose supplement regimen (vitamin C 2,000 mg, vitamin E 400 IU, beta-carotene 25,000 IU) "to protect my healthy cells." What should the oncology pharmacist advise?
A 67-year-old patient with metastatic prostate cancer takes a "hair and nail" supplement containing biotin 10 mg daily. His medical team notes a puzzlingly normal PSA despite radiographic progression, and a recent troponin drawn for chest pain was unexpectedly negative. What is the best pharmacist intervention?
You've completed this section
Continue exploring other exams