Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment

Anything that raises the chance of developing a cancer: smoking, alcohol, obesity, sunlight, certain infections, inherited genes, age. Having a risk factor does not mean getting cancer, and many cancers occur without any known one.

Excess body fat is an established cause of at least thirteen cancers, including womb, oesophagus, kidney, liver, bowel, pancreas and postmenopausal breast cancer. It is the second largest preventable cause of cancer after smoking in many countries.

Alcohol causes at least seven cancers and there is no safe threshold. Price, availability and cancer warning labels are the tools that work; most people still do not know alcohol causes cancer.

Processed meat (bacon, ham, sausages) definitely causes bowel cancer; red meat probably does. The risk per person is modest, but because so many people eat it, the population impact is large.

Diets high in industrially processed foods and sugary drinks are linked with more cancer, mainly through obesity but perhaps also through additives and packaging chemicals. Sugar itself does not 'feed' a tumour in the way social media claims.

Metabolic syndrome is a cluster of central obesity, high blood pressure, high blood sugar and abnormal blood fats. It raises the risk of several cancers and worsens outcomes after diagnosis, largely through high insulin levels.

IARC is the WHO's cancer agency, responsible for global cancer statistics (GLOBOCAN), carcinogen classification, and prevention research.

Scores that grade a whole diet against a healthy pattern instead of counting single foods. They predict cancer risk and survival better than any individual nutrient.

Three thousand breast cancer survivors were coached for years to eat far more vegetables, fruit and fibre. They did, and it made no difference to recurrence or survival.

The definitive test of whether vitamin D or fish-oil pills prevent cancer or heart disease in healthy adults. They did not.

The largest trial of vitamin D and fish-oil pills found they did not prevent cancer. A possible reduction in cancer deaths, and hints of benefit after a digestive cancer diagnosis, keep the question alive.

Fish oil rich in EPA was expected to slow cancer-related muscle wasting by damping inflammation. Randomised trials and a Cochrane review found no convincing effect on weight or survival, though fish oil is safe and sits comfortably inside general nutritional support.

Vitamin C tablets do not treat cancer: two randomised trials at the Mayo Clinic settled that in the 1980s. Intravenous doses reach blood levels high enough to generate hydrogen peroxide in tumours, and small trials alongside chemotherapy are under way, but no adequately sized trial has yet shown benefit.

Most people on cancer treatment take supplements, often without telling their team. Antioxidants, St John's wort, high-dose vitamins and some herbs can blunt chemotherapy or radiotherapy or interact with targeted drugs.

Diets marketed as cancer cures or preventives with no supporting evidence: alkaline diets, juice cleanses, Gerson therapy, apricot kernels and the like. Some are merely useless; several have caused harm or led people to delay effective treatment.

Because cancer cells burn a lot of glucose, many people conclude that cutting sugar starves tumours. The biology is real; the conclusion is not. Blood glucose is tightly regulated and no trial shows sugar restriction improves cancer outcomes.

The first randomised trial to show that a coached exercise programme after cancer treatment reduces recurrence and death, in colon cancer.

Canada's national academic trials group, which ran the CHALLENGE exercise trial and co-led the SABR-COMET oligometastasis trial.

Structured exercise during and after treatment, which the CHALLENGE trial showed improves survival in colon cancer.

A supervised, coached exercise programme for three years after bowel cancer treatment cut recurrence and death in a large randomised trial. It is the first lifestyle intervention proven to work like an adjuvant drug.

Moderate exercise while on chemotherapy is safe and reduces fatigue, helps people finish their planned doses, and may protect the heart and nerves.

Prehabilitation is a few weeks of structured exercise, nutrition and psychological preparation between diagnosis and surgery to make patients fitter for the operation and speed recovery.

PREHAB showed that four weeks of supervised training, protein and support before bowel cancer surgery cut severe complications and sped recovery, in an international randomised trial of 251 patients.

Instead of starving patients before and after an operation, modern surgical pathways feed them early, give carbohydrate drinks the night before, and get them walking the next day. Complications and hospital stays fall.

The CHALLENGE trial showed a supervised exercise programme improves survival in colon cancer. Extend it to breast, prostate, and lung cancer with the same rigour.

A large trial showed a structured exercise programme improved survival after bowel cancer. Almost no health system pays for it, so almost no patient gets it.

Getting fitter and better nourished before an operation reduces complications and speeds recovery. It is cheap, but only a few hospitals do it.

Screening for malnutrition, dietitian-led counselling, supplements and tube or intravenous feeding where indicated, plus treatment of cancer cachexia, the muscle-wasting syndrome that affects up to 80% of advanced patients.

Nutrition screening means weighing every patient, asking a few screening questions, and referring those at risk to a dietitian. It is simple, guideline-endorsed, and still not done routinely.

Quick questionnaires that flag who is at risk of malnutrition: recent weight loss, low BMI, poor appetite, illness severity. Anyone flagged should see a dietitian.

Nutrition support means tube feeding into the gut, or nutrition into a vein when the gut cannot be used. It is life-saving in the right patient, harmful or futile in the wrong one.

Drinks enriched with arginine, omega-3 fats and nucleotides for a week before a big operation seem to reduce infections afterwards, though the trials are old and mostly industry-funded.

Diets built around vegetables, wholegrains, legumes, nuts, fish and olive oil, with little red or processed meat, are linked with lower cancer risk and better survival after diagnosis. The evidence is strong for the pattern, weak for any single food.

Being overweight after breast cancer is linked with more recurrence, so a 3,000-woman trial tested a two-year telephone weight-loss programme. Women lost weight, but the trial did not clearly show fewer recurrences.

BWEL is a trial of more than 3,000 women testing whether losing weight after breast cancer treatment reduces recurrence. The programme achieved weight loss; the effect on recurrence was not clearly shown at the first analysis.

The European clinical nutrition society whose guidelines on nutrition in cancer patients define screening for malnutrition and the treatment of cachexia in oncology.

Sarcopenia is loss of muscle mass and strength. In cancer it predicts worse chemotherapy side-effects, more surgical complications and shorter survival, and it can hide in people who look a normal weight or overweight.

Patients who eat plenty of fibre and avoid probiotic pills seem to respond better to immunotherapy for melanoma, probably because fibre feeds the right gut bacteria. A proper trial is under way.

Transplanting gut bacteria from patients who responded to immunotherapy into those who did not. In small studies a minority of resistant melanomas started responding. Randomised trials are running.

Fifteen melanoma patients whose immunotherapy had failed received a stool transplant from someone whose immunotherapy had worked, then restarted the drug. Six of them benefited, including three with lasting responses.

Twenty melanoma patients took stool capsules from healthy donors before starting immunotherapy. Thirteen responded, more than usually expected, and the transplant was safe.

Antibiotics in the weeks before immunotherapy are linked with worse outcomes, and shop-bought probiotics may not help and might hurt. Avoiding both where possible is a low-cost precaution.

Changing the gut bacteria of a patient whose immunotherapy stopped working, in the hope of restarting the response.

How many different kinds of bacteria live in the gut and which ones dominate. Higher diversity and certain species are linked with better immunotherapy response; antibiotics and poor diet reduce both.

MaaT Pharma makes gut microbiome treatments for people with blood cancer. Its lead product restores gut bacteria to treat a severe complication of stem cell transplants when standard drugs fail.

GLP-1 agonists, the new weight-loss injections, lower weight by 15-20%. Early observational data suggest fewer obesity-related cancers in people who take them, but no trial has yet tested cancer as an outcome.

People with severe obesity who have weight-loss surgery develop about a third fewer cancers over the following decade, especially womb and other hormone-related cancers, than similar people who do not.

Obesity raises the risk of 13 cancers. Weight-loss drugs are now widely used; a large trial should test whether they actually prevent cancer, not just diabetes and heart disease.

Womb precancer in women with obesity is usually treated with a hormone coil or hysterectomy. Weight-loss drugs might reverse it and protect fertility.

Eating very little for a few days around each chemotherapy dose might protect normal cells and sensitise the tumour. Early trials are intriguing but small, and it is not something to try without a dietitian.

A ketogenic diet is a very-low-carbohydrate, high-fat diet that makes the body run on ketones. The idea is to starve brain tumours of glucose. It is safe and feasible for a few months, but no trial has shown it makes people live longer.

The only randomised trial of a ketogenic diet in brain tumours found no benefit. Patients could follow the diet and their ketone levels rose, but progression came just as quickly.

Time-restricted eating means eating within a window of 8-12 hours a day and fasting overnight. It improves blood sugar and weight a little; whether it changes cancer risk or recurrence is unknown.

Severe loss of weight and muscle in advanced cancer that eating more cannot reverse on its own. It affects up to eight in ten patients with advanced disease and contributes to a fifth of cancer deaths.

Treating the wasting that kills many cancer patients, by blocking the hormone that suppresses appetite.

The first drug to hit the hormone behind cancer wasting: patients on the highest dose gained nearly 3 kg more than placebo in 12 weeks and reported better appetite and more activity.

Cachexia pharmacotherapy covers three drug approaches to cancer wasting: a new antibody that blocks the hormone suppressing appetite, an appetite hormone mimic approved only in Japan, and a very cheap old tablet. None is yet standard everywhere; all beat what came before.

A randomised trial in India of a 2.5 mg dose of a decades-old, very cheap tablet. Six in ten patients gained more than 5% of their weight, against one in ten on placebo.

Lifting weights and eating enough protein is the only treatment shown to build muscle in people with cancer wasting, but most are too unwell to do it alone and the trials are small.

A new antibody blocks the hormone that makes people with cancer lose appetite and weight. Weight regained as muscle, not fat, needs exercise and protein alongside it.

Wasting kills many cancer patients and makes treatment impossible. With the first effective anti-cachexia drug in phase 3, the next question is whether starting it early prevents wasting rather than reversing it.

CHALLENGE proved exercise works in colon cancer but not how much is needed. A trial comparing doses, as we would for a drug, would tell health systems what to fund.

The CHALLENGE trial showed a supervised exercise programme improves survival in colon cancer. Extend it to breast, prostate, and lung cancer with the same rigour.

Half of people with cancer sleep badly, so sleep and body-clock interventions matter. Talking therapy for insomnia works well and is under-used; whether fixing sleep or body-clock disruption changes the cancer itself is unproven.

Insomnia therapy works well for cancer survivors and is barely offered. A trial that fixes sleep and then follows recurrence would test whether restoring the body clock changes the disease as well as the symptom.

Using complementary approaches with real evidence, such as acupuncture for nausea and pain, yoga and mindfulness for anxiety and fatigue, alongside standard treatment, while steering patients away from unproven 'alternative' therapies that can shorten life.

Gentle yoga combining postures, breathing and relaxation reduces fatigue, anxiety and low mood and improves sleep and quality of life, in many randomised trials mostly in women with breast cancer. Guidelines recommend it during treatment for anxiety and fatigue.

Offer the complementary approaches that have evidence (acupuncture for nausea and pain, exercise, mindfulness, yoga) inside the cancer centre, so patients do not seek them, and worse, elsewhere.

Wasting and treatment intolerance stop many patients from receiving the doses that would work. Treating the patient, not just the tumour, lags far behind.

Around four in ten cancers are preventable with tools we already own: vaccines, tobacco control, weight, alcohol, sun and infection control.

Patients are sold unproven treatments and frightened away from proven ones.

Old, cheap drugs with anti-cancer signals never get the trials they need because no one profits from the result.

Money goes to the cancers and questions that are easy or popular, not the ones with the greatest burden or where a dollar would do most.

Most people do not know alcohol causes seven cancers. Ireland is putting cancer warnings on bottles; other countries should follow and measure the effect on drinking.

Scotland's minimum price per unit cut alcohol deaths. Tracking alcohol-related cancer incidence over the next decade would show whether it also prevents cancer.

Stopping smoking after a cancer diagnosis improves survival, reduces treatment complications and second cancers, and is the single most effective supportive intervention that oncology services still routinely fail to deliver.