Quotations by Jason Fung

According to USPSTF guidelines, men younger than fifty-five or older than seventy should not be tested for PSA. Between ages fifty-five and sixty-nine, it is an individual choice. They note that “Screening offers a small potential benefit of reducing the chance of death from prostate cancer in some men. However, many men will experience potential harms of screening.” [2020] - Jason Fung

Most of the thyroid cancers detected in screening do not require treatment. Finding and treating early disease is not useful. Only reducing the incidence of late-stage disease is useful, and these are not necessarily the same thing due to the occurrence of early metastasis. By some estimates, as many as one third of all adults have evidence of thyroid cancer, but the vast majority of these cancers do not produce symptoms or cause health problems. Finding and treating cancers that don’t need to be treated is not a useful strategy. [2020] - Jason Fung

When cancers progress in an orderly manner from precancerous stage to small tumor to large tumor to metastasis, screening succeeds. Screening to remove early cancers prevents the development of late cancers, and this saves lives. But if removal of early-stage cancer does not reduce late-stage cancer, screening is unsuccessful, and overdiagnosis becomes a problem. Not every early-stage cancer needs to be destroyed, as many small cancers are contained by the immune system and will never pose a serious health threat. With toxic treatments such as surgery, radiation, and chemotherapy, the treatment may be worse than the disease. [2020] - Jason Fung

Virtually any form of cellular or DNA damage may cause cancer, including chemicals, radiation, and viruses, but only under extremely specific conditions. The damage induced must be both sublethal and chronic. To cause cancer, cell damage cannot be too much or too little. An overwhelming injury will simply kill all the cells, leaving no chance for cancer to develop. Too little cellular damage, however, is simply repaired by the normal DNA-repair mechanisms. Chronicity is the second key attribute of carcinogens. A single large dose of radiation is far less carcinogenic than chronic low-level radiation. [2020] - Jason Fung

Autopsy studies find unsuspected prostate cancer in 30 percent of men over the age of fifty; 50 percent by age seventy; and an astounding 80 percent by age ninety. If he lives long enough, every man can expect to develop prostate cancer. An estimated 11.2 percent of the adult population harbors thyroid cancer. Despite this high incidence, thyroid cancer only very rarely causes death. Colonoscopy screening studies find adenomas (a precancerous lesion) in almost half of the general population by age eighty. [2020] - Jason Fung

Intermittent fasting is a promising nutritional approach for cancer prevention, as it protects against many of the risk factors such as obesity, type 2 diabetes, and inflammation. Low-carbohydrate diets reduce glucose and insulin, but not the other nutrient sensors, mTOR and AMPK. Fasting simultaneously reduces all the human nutrient sensors and most of the growth pathways, such as PI3K, mTOR, and IGF-1, and also increases autophagy and mitophagy. One recent study found that women who fast for fewer than thirteen hours per night, despite having a lower BMI than other women in the study who fasted for that duration, had a 36 percent higher risk of recurrent breast cancer. [2020] - Jason Fung

The term cancer chemoprevention was introduced by the NIH in 1976 to denote foods, supplements, or drugs that may block progression of cancer. One of the most promising chemopreventive drugs is the old diabetes drug metformin. Studies have demonstrated that in type 2 diabetics, metformin may potentially reduce the risk of cancer by as much as 21 percent to 57 percent. Specifically, long-term metformin use in women with type 2 diabetes was associated with a more than 50 percent reduction in breast cancer risk. Metformin works by reducing glucose to the growing cancer without the pro-growth effects of the insulin/IGF-1/PI3K pathway. It also activates AMPK, an important nutrient sensor and growth pathway, which rapidly inhibits cellular protein synthesis and growth. Some research has indicated that this beneficial anticancer effect might extend to nondiabetics as well. [2020] - Jason Fung

In 2000, researchers in Japan found that high consumption of green tea delayed the average age of cancer onset by 7.3 years and reduced breast cancer recurrence. Green tea extract supplements were shown to reduce the incidence of colorectal adenomas by over 50 percent in small pilot studies. In prostate cancer, green tea extracts block the progression of high-grade precancerous lesions. These studies are promising but highly preliminary, but green tea is one of the few chemopreventive tools that is a low-cost, natural food with no negative side effects. [2020] - Jason Fung

Immunotherapy has several inherent advantages over conventional treatments. First, the boosted immune system is a dynamic system that can better keep pace with cancer’s moves. Second, the immune system has a memory, so it may prevent recurrence. Third, immunotherapy has fewer side effects than standard chemotherapies. Fourth, immunotherapy is a systemic treatment, which is crucial because cancer is a systemic disease. Affordability, though, is not one of the advantages of immunotherapy. Given the exorbitant price tag of these treatments, many providers question the feasibility of using these advanced drugs. [2020] - Jason Fung