Cognitive side effects to chemotherapy, often called “chemobrain” or “chemofog”, are a growing concern among cancer survivors. Symptoms such as a decline in memory, concentration and executive functions (such as organization or attention) are often described. Cognitive changes can cause significant distress and prevent a return to the quality of life experienced before treatment.

Recent studies have started to unravel the way chemotherapy agents affect the brain. Imaging of patients after chemotherapy show that treatments produce structural and functional changes in the brain. A number of explanations have been suggested for these changes after chemotherapy. Inflammatory changes in the brain, low hormone levels, or toxic destruction of nerve cells are a few examples.

Currently, there is no recognized treatment for cognitive dysfunction following chemotherapy. A greater understanding of the causes for cognitive decline will be key to finding ways of preventing or treating the effects of chemobrain.

Some studies have focused on the ability of the hippocampal region of the brain to form new nerve cells (called neurogenesis). Several cognitive and mood disorders, such as memory decline, fatigue and depression, have been linked to problems with neurogenesis.

Two recent studies investigating breast cancer patients focused specifically on the hippocampus. In one study, breast cancer survivors showed an average reduction of 8% in hippocampal size compared with healthy controls. Hippocampal shrinkage in this study was associated with the ability to retrieve facts from memory. Similarly, a second study found that the size of the hippocampus on the left side of the brain was reduced by nearly 7% in chemotherapy-exposed patients compared with healthy controls. Left hippocampal size was associated in this study with verbal memory performance (such as remembering words). Additional studies have also linked reduced hippocampus size in chemotherapy-exposed patients with deficits in figural and visual memory.

Only a few studies have reported chemotherapy-related effects on hippocampal function (rather than size). In all of these studies, activation of the hippocampus was less effecient and less functional in patients treated with chemotherapy.

Taken together, an increasing number of studies suggest that cognitive dysfunction following chemotherapy is associated with changes in the hippocampal region of the brain. Impaired hippocampal neurogenesis may be a contributing factor to cognitive decline, and key to preventing or treating chemobrain.

This paper studied the safety and effectiveness of yttrium-90 radioembolization (use of radiation to cut off blood flow) in breast cancer that has spread to the liver.

This study investigated whether baseline levels of the female hormone FSH (follicle stimulating hormone) can predict bone loss.  

The study concluded that among premenopausal women with breast cancer treated with chemotherapy, baseline FSH levels were strongly associated with subsequent bone loss. 

This study looked at men who had their prostate removed after diagnosis of prostate cancer. The study evaluated the time from surgery to biochemical recurrence, and whether this period of time is associated with survival or certain cancer characteristics.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

In an article entitled “The Treatment of Inoperable Cancer”, it was noted that “200 years ago, it was observed that a certain number of malignant growths disappeared after an attack of [a type of strep infection]”—and that was 200 years before 1901, when this was published. A disproportionate number of cases of spontaneous tumor regressions have followed various infections. The thought is that an infection may kind of so rile up the immune system, the cancer may get caught in the cross-fire—a phenomenon that may have inspired healers dating back to the ancient Egyptians, thousands of years ago.

But, you don’t know until you put it to test—though it wasn’t formally studied until the 1800s, when doctors started intentionally infecting cancer patients. The most famous proponent was William Coley, the so-called “Father of Immunotherapy,” at what would eventually become Memorial Sloan Kettering. He “was convinced that having a severe infection could cause cancer to regress.” So, with “a great deal of courage,” he started injecting cancer patients. The problem, of course, is that causing infections is quite dangerous, and “two of his patients died.” However, their tumors did shrink!

If only there was a way we could boost the immune system without killing people. Well, that’s the theory behind therapeutic cancer vaccines—one of which has been in practice for decades: squirting a weakened bovine tuberculosis bacteria into the bladders of patients with bladder cancer, to make the immune system attack; boosting long-term survival up to 36%.

Okay, but is there something we can eat that can boost immune function? In my videos on countering stress-induced immune suppression and preventing common childhood infections, I reviewed evidence about a type of fiber in baker’s, brewer’s, and nutritional yeast, called “beta-glucans…[which] are considered immunomodulatory compounds suggested to enhance the defense against infections” and, potentially, cancer.

Beta-glucans themselves do not appear to have a direct cytotoxic effect in terms of killing cancer cells, but may boost anti-tumor immunity by activating our immune cells. For example, if you take freshly excised tumors of breast cancer patients, and let loose natural killer cells upon them, they can kill off a small percentage of the tumor cells. But, first prime them in vitro with some yeast beta-glucans, and they become five times more effective at killing cancer cells. What if you just eat it, though?

When twenty-three women with metastatic breast cancer were given just a 16th of a teaspoon of nutritional yeast worth of beta-glucans, they experienced a 50% increase in the number of monocyte white blood cells in their bloodstream (which are part of our natural defenses), as well as a significant increase in their activation. But, it was just a two-week study. The clinical significance of this finding is unclear. What we want to know is if they actually live longer.

The only English-language, randomized, double-blind, placebo-controlled trial of breast cancer patients and beta-glucans was more of a wound-healing study, where they found that the women taking beta-glucans healed so much faster after surgery that the tubes could be removed from their chests and armpits—in some cases, days earlier. This was the first clinical study to demonstrate improved wound healing using oral beta-glucans. The other two—showing benefits for pediatric burns and leg ulcers—were performed using topical beta-glucan preparations: putting it on the skin directly, something that did not appear to reverse precancerous skin lesions better than placebo. But, that’s because the placebo cream worked so well, too. “Both groups showed a…significant reduction.” They speculated that “[s]ince each patient…acted as their own control,” putting the beta-glucan cream on one arm, and the placebo cream on the other, that the application of beta-glucans on one arm may have been absorbed into the system, and helped on the other arm, given that systematic effects have been noted following topical administration.

But, what effect might oral beta-glucans have on the progression of internal cancers? Yeah, oral yeast beta-glucans can cause dramatic tumor shrinkage—in mice, but there appears to be only one human study published in English. Twenty patients with advanced cancer on chemo were given a beta-glucan supplement in an open label, uncontrolled trial. “Sixty percent of the patients [supposedly] reported a sense of well-being while taking the [beta]-glucan, and asked to remain on the treatment…after the completion of the study.” But, that just sounds like classic placebo effect. Same thing with reporting being less tired, but this is interesting: “one patient with lymphoma and [enlarged lymph nodes in the neck] who delayed his standard chemotherapy for 4 weeks during the study…noted a marked reduction in the size of the nodes while taking the [supplement] alone.” So, this, you know, one kind of anecdotal case is interesting, especially since there are no side effects, but not exactly revolutionary.

In Japan, there have been more than 20 randomized, controlled trials on the use of beta-glucans as an adjunct cancer treatment, which evidently show an enhancement of chemo or radiation therapy, resulting in “a positive effect on the survival and quality of life…” For example, there was evidently a study on taking a yeast beta-glucan supplement to help “cancer relapse after surgery. There were no relapses in the treated group compared to [about one in five] in the control group.” Even more intriguing, yeast beta-glucans for inoperable cancer patients—end-stage cancer, since only about one in 20 patients made it three months. And by six months, they were all dead, “whereas in the treated group, [most] survived for more than 3 months”—not one in 20, but most, “and 43% were still alive after 6 months.”

Now evidently, it’s not clear how patients were divvied up into treatment vs. control groups. If they weren’t randomly assigned, they may have inadvertently cherry-picked healthier patients for the treatment group, which could explain the results. Now, I’ve looked for this study everywhere so I could get it translated, but even the National Library of Medicine couldn’t find it. If anyone out there can, though, I’ll do a follow-up video. But, the amount of beta-glucan they used is what you’d find in a single pinch of nutritional yeast, which would cost less than a penny. And the only side effect would be tastier popcorn. So, why not give it a try?

This paper studied whether adding the 70-gene signature (MammaPrint) to clinical guidelines could improve prediction of cancer outcome in early breast cancer patients.  

This study looked at different types of physical training to improve gait while carrying out tasks in stroke patients. The authors concluded that both cognitive and motor dual task training could be combined for the most benefit.

This phase 2 clinical trial investigated whether transdermal estrogen or TE (estrogen absorbed through the skin) could be used as an effective treatment in patients with advanced prostate cancer (PCa), while also avoiding the long-term cardiovascular or CV (heart and blood vessels) complications associated with luteinizing hormone-releasing hormone agonists (LHRHa).

This paper compared glucose intolerance (high glucose levels) in female breast cancer patients at initial diagnosis and during chemotherapy.