Cancer Prevention: The Functional Medicine Blueprint

The Prevention Imperative

The World Health Organization estimates that 30-50% of all cancers are preventable through modifiable lifestyle and environmental factors. That is not a marginal number. It means that for every ten people who will develop cancer, three to five of them could have avoided it entirely — not through luck, not through genetics they cannot control, but through daily decisions within their reach.

Functional medicine is, at its core, a prevention discipline. It asks what upstream conditions create disease decades before a diagnosis. In cancer prevention, this upstream thinking is everything. The tumor that appears at 55 was seeded by the terrain at 35 — the insulin resistance, the chronic inflammation, the toxin accumulation, the sleep deprivation, the unmanaged stress.

This is not about fear. It is about agency.

The Insulin-Cancer Connection

If there is a single metabolic thread connecting obesity, diabetes, and cancer, it is insulin. Hyperinsulinemia — chronically elevated insulin — is one of the most potent and underappreciated cancer promoters in modern medicine.

Insulin acts as a growth factor. It activates the IGF-1 (insulin-like growth factor 1) receptor, which signals cells to grow and divide. It activates the PI3K/Akt/mTOR pathway — the same pathway that many targeted cancer drugs attempt to block. Elevated insulin suppresses IGFBP (binding proteins that sequester IGF-1), freeing more IGF-1 to stimulate growth.

The International Agency for Research on Cancer (IARC) has identified 13 cancer types linked to obesity: esophageal adenocarcinoma, gastric cardia, colorectal, liver, gallbladder, pancreatic, post-menopausal breast, endometrial, ovarian, renal cell, meningioma, thyroid, and multiple myeloma. The mechanism for most of these runs directly through insulin and IGF-1, compounded by adipose-tissue inflammation and estrogen production from aromatase in fat cells.

Testing: fasting insulin (optimal <5 mIU/L), fasting glucose (<90 mg/dL), HOMA-IR (<1.5), HbA1c (<5.3%). These are functional ranges — tighter than standard lab reference ranges — because prevention operates at a different threshold than disease diagnosis.

Diet: The Foundation of Cancer Prevention

Mediterranean Diet

The PREDIMED trial (Toledo 2015) delivered one of the most striking dietary findings in cancer prevention: women randomized to a Mediterranean diet supplemented with extra virgin olive oil had a 62% lower incidence of breast cancer compared to the control group. The magnitude of this effect rivals pharmaceutical interventions.

The Mediterranean pattern works through multiple mechanisms: anti-inflammatory polyphenols from olive oil, omega-3 fatty acids from fish, fiber supporting a healthy microbiome, low glycemic load reducing insulin signaling, and phytochemicals from abundant vegetables.

Cruciferous Vegetables

Broccoli, cauliflower, Brussels sprouts, kale, cabbage, and arugula contain sulforaphane — a potent inducer of Phase 2 liver detoxification enzymes. Hecht’s 2000 research demonstrated that cruciferous vegetable consumption enhanced urinary excretion of carcinogen metabolites. Sulforaphane also inhibits histone deacetylase (HDAC), an epigenetic mechanism that silences tumor suppressor genes.

Practical target: 1-2 servings daily. For maximum sulforaphane yield, chop broccoli and let it sit for 40 minutes before cooking (allows myrosinase enzyme activation), or add mustard seed powder to cooked cruciferous vegetables.

Fiber

Every 10-gram increase in daily fiber intake is associated with a 10% reduction in colorectal cancer risk. Fiber feeds butyrate-producing bacteria in the colon — butyrate is a short-chain fatty acid that directly inhibits colorectal cancer cell growth, promotes apoptosis, and maintains intestinal barrier integrity. Target: 35-50 grams daily from whole food sources.

What to Limit

• Processed meat: IARC Group 1 carcinogen (same classification level as tobacco and asbestos). Each 50g daily serving increases colorectal cancer risk by 18%. This includes bacon, sausage, hot dogs, deli meats, jerky.
• Red meat: IARC Group 2A (probably carcinogenic). Limit to 1-2 servings per week maximum. Mechanisms include heme iron (generates N-nitroso compounds), heterocyclic amines from high-temperature cooking, and Neu5Gc inflammatory response.
• Sugar and refined carbohydrates: Drive hyperinsulinemia, the growth factor pathway described above. Not classified as carcinogens per se, but their metabolic effects clearly promote the cancer terrain.

Anti-Cancer Nutrients

Vitamin D

Maintain serum 25(OH)D at 50-80 ng/mL for cancer prevention. Vitamin D regulates over 200 genes involved in cell differentiation, apoptosis, and immune surveillance. Dose: 4,000-10,000 IU/day, adjusted to blood levels. Test every 3-6 months initially.

Selenium

The SELECT trial complicated selenium’s cancer prevention story — high-dose selenium (200 mcg selenomethionine) did not prevent prostate cancer and may have increased diabetes risk in selenium-replete men. The nuance: selenium benefits those who are deficient. Optimal serum selenium is 120-150 ng/mL. Dose: 100-200 mcg/day from selenomethionine or selenium-rich foods (2-3 Brazil nuts daily provide approximately 200 mcg).

Curcumin

1,000-2,000 mg/day of bioavailable curcumin. Inhibits NF-kB (the master inflammatory switch), COX-2, and multiple oncogenic signaling pathways. Population data from India — where turmeric consumption is high — shows lower rates of several cancers.

EGCG (Green Tea)

3-5 cups of green tea daily or 400-800 mg EGCG supplement. Inhibits angiogenesis, promotes apoptosis, modulates estrogen metabolism. Japanese population studies consistently show dose-dependent cancer risk reduction.

Additional Protective Compounds

• Lycopene: 10-30 mg/day. Concentrated in cooked tomatoes. Protective for prostate cancer (Chen 2015 meta-analysis).
• Resveratrol: 250-500 mg/day. Activates SIRT1, inhibits NF-kB, promotes apoptosis. Found in grape skins, red wine (though alcohol itself is a carcinogen — see below).
• Sulforaphane: 30-60 mg/day from broccoli sprout extract if dietary intake is insufficient.
• Modified Citrus Pectin: 5-15g/day. Blocks galectin-3, which promotes metastasis.
• IP6 (Inositol Hexaphosphate): 1-4g/day. Found in whole grains and legumes. Enhances NK cell activity, inhibits cancer cell growth in vitro. Clinical evidence still emerging but mechanism is well-characterized.

Detoxification — Reducing Toxic Burden

We are exposed to more synthetic chemicals than any generation in history. The Environmental Working Group (EWG) has identified over 200 industrial chemicals in umbilical cord blood — we begin life pre-polluted.

Reduce Exposure

Use EWG’s Skin Deep database for personal care products, Dirty Dozen/Clean Fifteen for produce, and avoid storing food in plastic (especially heated). Filter drinking water (activated carbon minimum, reverse osmosis ideal). Choose organic for the Dirty Dozen produce items.

Support Liver Detoxification

• Phase 1 (CYP450 activation): B vitamins, iron, glutathione, flavonoids
• Phase 2 (conjugation): Sulforaphane (cruciferous vegetables), glutathione/NAC, glycine, taurine, methylation support (folate, B12, B6)
• Phase 3 (transport/elimination): Fiber for fecal elimination, hydration for urinary excretion, sweat for dermal elimination

Sweat

Sauna use (infrared or Finnish, 3-7 sessions/week) enhances toxin elimination through perspiration. Sears 2012 demonstrated that sweat contains measurable quantities of heavy metals, BPA, and phthalates. Beyond detoxification, regular sauna use is associated with reduced all-cause mortality (Laukkanen 2015 — Finnish cohort).

Exercise — The Universal Cancer Preventive

150-300 minutes per week of moderate-intensity aerobic exercise reduces risk of breast cancer by 25-30%, colon cancer by 20-25%, and prostate cancer by 10-20%. The mechanisms are comprehensive: reduced insulin and IGF-1, improved immune surveillance (enhanced NK cell activity), reduced chronic inflammation, improved body composition, enhanced detoxification through increased circulation and sweating, and improved hormonal balance.

Resistance training adds metabolic benefits through increased lean mass, improved insulin sensitivity, and growth hormone modulation.

The single most impactful exercise recommendation for cancer prevention: move daily. Walk after meals. Take the stairs. Garden. Dance. The body was built to move, and stillness is a cancer risk factor in its own right.

Stress and Cancer

Chronic psychological stress does not merely “weaken the immune system” in some vague way. The mechanisms are specific and documented.

Thaker’s 2006 research demonstrated that norepinephrine and epinephrine — the stress catecholamines — directly promote angiogenesis (tumor blood supply) and metastasis through beta-adrenergic receptor signaling on tumor cells. Chronic stress suppresses NK cell activity — the immune cells most responsible for identifying and destroying circulating tumor cells.

The clinical implication: stress management is not a luxury in cancer prevention. It is a biological intervention. MBSR, yoga, tai chi, time in nature, creative expression, social connection, therapy for unresolved trauma — all of these modulate the neuroendocrine pathways that influence cancer terrain.

Sleep — The Circadian Guardian

IARC classifies shift work involving circadian disruption as a Group 2A probable carcinogen. Nurses who worked rotating night shifts for 20+ years had significantly increased breast cancer risk (Schernhammer 2001, Nurses’ Health Study).

The mechanism centers on melatonin. Melatonin, produced by the pineal gland in darkness, is an oncostatic hormone — it inhibits cancer cell proliferation, promotes apoptosis, and is a powerful antioxidant. Light exposure at night suppresses melatonin production.

Cancer prevention sleep protocol: 7-9 hours in a dark room, consistent sleep/wake times, minimize blue light after sunset, consider low-dose melatonin (0.5-3 mg) if sleep quality is poor.

Screening — Beyond the Standard

Standard cancer screenings (mammography, colonoscopy, PSA, Pap smear) catch cancer once it exists. Functional screening catches the terrain shifts before cancer develops:

• Vitamin D: 25(OH)D, target 50-80 ng/mL
• Fasting insulin: Target <5 mIU/L
• hs-CRP: Target <0.5 mg/L (chronic inflammation marker)
• HbA1c: Target <5.3% (insulin resistance surrogate)
• Fasting glucose: Target <90 mg/dL
• Homocysteine: Target <8 umol/L (methylation marker)
• Omega-3 Index: Target 8-12% (inflammation modulation)

These are not cancer-specific tests. They are terrain-specific tests — metabolic indicators of the soil in which cancer might or might not take root.

Alcohol — The Uncomfortable Truth

Bagnardi’s 2015 meta-analysis confirmed what the evidence has been showing for decades: there is no safe level of alcohol consumption for cancer prevention. Even light drinking (1 drink/day) increases risk of breast, oral, and esophageal cancers. Each 10g of alcohol per day (less than one standard drink) increases breast cancer risk by approximately 7-10%.

Alcohol is metabolized to acetaldehyde — a direct carcinogen that causes DNA damage. It also increases estrogen levels, depletes folate (necessary for DNA repair), and increases intestinal permeability (allowing endotoxin absorption and liver inflammation).

This does not mean that everyone who drinks moderately will develop cancer. It means that any honest cancer prevention protocol must acknowledge alcohol as a modifiable risk factor, not a health food.

The Blueprint in Practice

Cancer prevention is not a single dramatic intervention. It is the accumulation of daily choices that, over decades, shape the biological terrain:

1. Keep insulin low (whole food, low glycemic, time-restricted eating)
2. Eat abundantly from the plant kingdom (fiber, polyphenols, sulforaphane)
3. Move your body daily (150-300 min/week minimum)
4. Sleep in darkness (7-9 hours, consistent rhythm)
5. Manage stress as if your life depends on it (because it does)
6. Reduce toxic exposure (food, water, air, skin products)
7. Support detoxification (sweat, fiber, liver nutrients)
8. Maintain vitamin D above 50 ng/mL
9. Minimize alcohol
10. Screen for metabolic terrain, not just tumors

None of these require a prescription. All of them require commitment. The question is not whether prevention works — the data is overwhelming that it does. The question is whether we are willing to invest in the terrain today to prevent the crisis tomorrow.

If cancer is partly a disease of the soil, what are you feeding yours?