January 19, 2023 – Cancer nutritionist Lisa Cianciotta often finds herself sitting across from a patient who suddenly pulls a bottle of antioxidant supplement from her bag, saying, “My friend told me this works great,” or “I read on the internet that this is supposed to be very good for cancer.”
While taking an antioxidant pill sounds harmless, Cianciotta, a clinical dietitian who works with cancer patients at New York-Presbyterian Hospital in New York City, is well aware that the popular dietary supplement can interfere with patients’ radiation or chemotherapy.
But many cancer patients believe that these over-the-counter vitamins, minerals, or herbs will help them, and most use At least one dietary supplement and their cancer treatment.
This had Cianciotta having a delicate conversation in front of her.
Drug-supplement interactions are complex, often vary by supplement, cancer, and type of treatment, and can do more harm than good.For example, popular dietary supplements may counteract the effects of cancer treatment, making it less effective, or increasing serious side effects such as liver toxicityBut in other cases, Cianciotta said, vitamin D supplementation may be beneficial for patients who are deficient in the vitamin.
Interactions of these drugs with supplements are difficult to determine because more than two thirds of doctors unaware their patients were using supplements.
Here’s what patients need to know about the potential risks of using supplements during treatment, and how oncologists can address this thorny and often poorly understood topic.
Complex Drug Complementation Landscape
list of dietary supplements and how they interact The different treatments and cancer types are long and subtle.
But certain supplements appear to affect cancer treatment regardless of other factors and should be avoided. Any supplement that strongly alters the body’s cytochrome P450 levels would be an example. This group of enzymes plays a key role in metabolizing drugs, including chemotherapy and immunotherapy drugs.
certain supplements John’s wort extract — best known as St. John’s wort extract — may decrease or increase the activity of cytochrome P450s, which can affect blood levels of cancer-fighting drugs, said William Figg, MD, deputy director of the National Cancer Institute in Bay, Maryland. The Cancer Institute at Thesda.For example, studies have shown that this common herbal supplement increases the activity of cytochrome P450s, which leads to lower level cancer drugs.
In addition to drug metabolism, patients with hormone-related cancers such as breast and prostate should avoid taking dietary supplements that alter testosterone or estrogen levels, Figg said. For example, the evergreen shrub ashwagandha is marketed to reduce stress and fatigue, but can also increase testosterone levels – This is a potential problem for men with prostate cancer undergoing androgen deprivation therapy, which lowers testosterone levels.
Many oncologists advise patients not to use dietary supplements based on antioxidants — especially turmeric and green tea extracts — Although they have radiation therapy and some chemotherapy. These therapies work by producing large quantities of highly reactive molecules called free radicals in tumor cells, which increase the stress within those cells, eventually killing them.In theory, antioxidants could neutralize this effect, say Skyler Johnson, MD, is a radiation oncologist at the Huntsman Cancer Institute at the University of Utah in Salt Lake City. Several studies have shown that antioxidant supplements may mitigate the impact radiotherapy and chemotherapy, although mixed evidence.
Some dietary supplements, including high doses green tea extract and Vitamin A, can cause kidney or liver toxicity, and “many cancer patients already have compromised kidney or liver function,” says Jun J. Mao, MD, director of integrative medicine at Memorial Sloan Kettering Cancer Center in New York City. Even herbal remedies that do not interfere with the efficacy of anticancer drugs, such as steviaIncreased treatment-related side effects such as nausea and vomiting.
Another potential problem with dietary supplements: It’s nearly impossible to know exactly what’s in them.For example, just last year, the FDA sent Nearly 50 warning letters To companies marketing dietary supplements. The problem is that federal manufacturing regulations are less stringent for supplements than they are for drugs. Therefore, some supplements contain ingredients not listed on the label.
one historical example yes Complementary PC-SPES, a blend of eight herbs, marketed to men with prostate cancer. The supplement was recalled in 2002 after certain batches were found to contain traces of prescription drugs, including diethylstilbestrol, ethinyl estradiol, warfarin and alprazolam.
To complicate matters further, some dietary supplements may help. Most cancer patients “are malnourished and miss out on the nutrients they can get from food,” Cianciotta said.
Patients are regularly tested for vitamin deficiencies and receive supplements as needed, she said. Vitamin D and folic acid were the two most common deficiencies in this patient group. Vitamin D supplements can improve outcomes in patients undergoing stem cell transplants by helping to engraft and rebuild the immune system, while folic acid supplements can help improve low red blood cell counts and hemoglobin levels.
While she rarely sees vitamin toxicity, Cianciotta stresses that supplement use is not always better, and that even when it seems safe or necessary due to a deficiency, it should be taken under supervision and carefully by the patient’s care team. monitor.
Bringing Supplement Use into the Light
Many times, providers are unaware of patients’ supplement use.
A central reason: Dietary supplements are often touted as natural, which many patients equate with being safe, says Samantha Heller, a senior clinical dietitian at NYU Langone Health in New York City.
This means that patients may not be aware that supplements can act like drugs and interfere with their cancer treatment, and therefore may not realize the importance of telling their doctors.
Still, the promise of herbs, vitamins, and minerals is enticing, and there are many reasons why patients decide to get involved. A major attraction: Dietary supplements can help some patients feel empowered.
“Cancer is a disease in which the individual loses a lot of control. Taking supplements or herbs is a way to regain a sense of control,” Mao said.
The phenomenon could also be cultural, he said. Some people take herbs and supplements from an early age to maintain health or combat health problems.
Pressure or advice from family or friends, who may think they are helping a loved one with dietary advice, may also play a role. Friends and family “can’t prescribe chemotherapy, but they can buy herbs and supplements,” Mao said.
Medical oncologist William Dahut, MD, explains that patients seeking greater control over their health or experiencing high levels of anxiety may be more likely to take the advice of friends and family or to believe falsehoods about the efficacy or safety of supplements Or a misleading statement, Chief Scientific Officer of the American Cancer Society.
Plus, social media often amplifies and normalizes this misinformation, Johnson noted.in a 2021 Research Published on Journal of the National Cancer Institutehe and colleagues found that one-third of the most popular articles about cancer care posted on social media in 2018 and 2019 contained false, inaccurate or misleading information, often harmful.
According to Johnson, some of the false claims centered on unproven and potentially unsafe herbal remedies. These include “Lung cancer can be cured with cannabis oil” and “Goldberry cures and prevents cancer.”
Given the exaggerated “cure” claims, some patients may keep supplement use under the radar for fear of being judged or criticized.
“Clinicians should avoid making patients feel judged or telling people not to go online and do their own research,” Johnson said.
Instead, directing patients to accurate online sources of information could be one way to help patients feel empowered, he said. Cancer.gov and Memorial Sloan Kettering Cancer Center About the Herbal Database Providing healthcare professionals and patients with accessible and accurate information about dietary supplements and cancer treatments, he noted.
If a supplement is unsafe during treatment, the provider should be able to explain why, Cianciotta said.in a A recent studyEighty percent of health care providers surveyed thought there could be a problem with interactions between herbs and medications, but only 15 percent could explain why.
“Being able to explain why we’re discouraging the use of a particular supplement right now is often more acceptable than just telling patients not to take something because it’s bad,” she said.
Another key is listening carefully to patients to understand why they are taking a particular supplement. Does the patient feel out of control? Is nausea a problem?
“Having patients tell you why they use a particular supplement often reveals unmet needs or psychosocial challenges,” Mao said. This information can allow providers to suggest evidence-based alternatives, such as mindfulness meditation or acupuncture, to manage stress.
What if the patient got dietary supplements from well-meaning family and friends?
“Simply telling a patient that a certain supplement is useless or harmful can create family tension,” Mao said.
Instead, he suggested reframing the question.
“We want to better understand how patients tolerate chemotherapy or immunotherapy before putting other things on top. Let them know that now might not be the right time to add a supplement,” Mao said.
The bottom line: “Patients want to take an active role in their own care, and we want to help them do that in a safe way,” he said.