Recurring formats from the Institute, built for depth over headlines.
Dr. Johnston reviews a 2024 study of 1.65 million people with type 2 diabetes in which GLP-1 use was associated with lower risk of 10 of 13 obesity-related cancers compared with insulin, a 2025 comparison with bariatric surgery, and a laboratory finding involving natural killer cells. The studies are observational and cannot prove GLP-1 drugs prevent cancer.
Dr. Johnston reviews a 2025 observational study of more than 86,000 matched adults with overweight or obesity, with and without diabetes. Cancer rates were lower among GLP-1 users, including 17% lower relative risk overall. He notes the study cannot prove GLP-1 drugs prevent cancer.
Dr. Johnston describes a 2025 analysis of 21 prospective studies, with over 108,000 cancer cases and 10,000 deaths, linking higher blood lycopene to lower cancer mortality, lung cancer death and breast cancer incidence. He also cites lab findings. The data are observational, so they show association only.
Dr. Johnston looks at a 2000 study comparing 571 melanoma patients with 913 healthy controls, which reported higher odds of melanoma among regular sunscreen users, and a 2023 meta-analysis of vitamin D3 and cancer mortality. He notes the sunscreens averaged only SPF 6 and that users may have stayed in the sun longer. Part 1 of 2.
Dr. Johnston looks at a 2026 phase II study in which 40 patients with advanced lung cancer or melanoma received donor gut bacteria in capsules before immunotherapy, and a 2026 analysis of 105 studies on probiotic use during immunotherapy. The phase II study was small, and the larger analysis reports associations rather than proof of cause.
Dr. Johnston follows the research on gut bacteria and cancer immunotherapy from mouse experiments to a small human trial in which 6 of 15 patients with advanced melanoma had a clinical benefit after a microbiome transfer and restarted immunotherapy. He also describes his own clinical experience, which he notes is not a controlled trial.
Dr. Johnston looks at a randomized, double-blind, placebo-controlled trial of sulforaphane in 78 men whose PSA was rising after prostate cancer surgery. The trial measured PSA, a lab marker, over 6 months, and did not measure survival.
Dr. Johnston looks at a 2019 meta-analysis of 15 randomized trials in 1,410 patients with stage III or IV non-small cell lung cancer, comparing chemotherapy alone with chemotherapy plus elemene injections. Elemene was given by injection and is a different compound from curcumin, so the findings do not apply to turmeric or curcumin supplements.
Dr. Johnston looks at laboratory research on the peptide BPC-157 in melanoma cells, and a mouse study of colon tumors and cancer-related weight and muscle loss. These are early laboratory and animal findings and do not establish safety or effectiveness in people with cancer.
Dr. Johnston looks at a 2023 analysis of more than 822,000 cancer patients on positive psychological states and survival, and a meta-analysis of more than 32,000 patients on religion, spirituality and health. These studies show associations, not proof that faith or optimism treats cancer.
Dr. Johnston looks at a 2016 laboratory study of dandelion root extract in human colon cancer cells, and a follow-up test in mice carrying human colon tumors. He notes there are still no adequate human cancer trials of dandelion root extract.
Mebendazole is a decades-old antiparasitic drug now being studied in cancer. Dr. Johnston looks at a 40-patient randomized, placebo-controlled trial that added it to chemotherapy for metastatic colorectal cancer. The trial was small, and larger studies are needed.
A phase II trial gave grape seed extract to 41 men whose prostate cancer had returned after local treatment, shown by a rising PSA. PSA doubling time lengthened, but the trial had no placebo group. This is an early human signal, not proof of benefit.
European mistletoe extract has been studied in cancer patients for decades. Dr. Johnston looks at a randomized trial in advanced pancreatic cancer that reported longer survival and better quality of life.
A Mayo Clinic phase 2 trial of green tea extract (EGCG) in chronic lymphocytic leukemia found measurable biological responses in a majority of patients. The trial had no placebo group.
A randomized, double-blind, placebo-controlled trial found fewer recurrent colorectal adenomas with berberine after polyp removal. This research is about polyp prevention, not cancer treatment.
Huaier is a medicinal mushroom with a long history of use in China. Dr. Johnston looks at a randomized study of 1,044 patients after surgery for hepatocellular carcinoma.
Astragalus has been used in traditional Chinese medicine for centuries. Dr. Johnston looks at analyses of randomized trials that added astragalus-based herbal medicine to chemotherapy in advanced lung cancer.
L-methylfolate is the active form of folate that skips the MTHFR step. Dr. Johnston explains how it differs from folic acid and points to a small glioma trial.
A 14-patient phase I trial of L-methylfolate in recurrent glioma found higher DNA methylation in tumors at autopsy, but showed no survival benefit over standard therapy.
Methylene blue affects how cancer cells make energy. The study cited used cell cultures and never tested red light, so this is early lab research, not proof in people.
A large analysis of observational studies linked statins to lower cancer mortality. Such studies cannot prove cause, and a bias-corrected analysis found no difference.
The ALASCCA trial found low-dose aspirin lowered 3-year colorectal cancer recurrence in tumors with PIK3CA changes (7.7% vs 14.1%). Aspirin also carries bleeding risks.
PSK, a Turkey Tail extract used in Japan, was tested in randomized trials alongside older chemotherapy. The survival signal is modest, and mushroom tea is not PSK.
A 2012 meta-analysis of 8 small trials found melatonin added to cancer treatment was linked to about twice the tumor response. The trials were small and mostly unblinded.
Dr. Johnston explains why Verity reviews published research on supplements and repurposed medications in cancer, and how every review states its evidence level.
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