Clinical Corner: Herb-Drug Interactions in Cancer Chemotherapy: Theoretical Concerns Regarding Drug Metabolizing Enzymes

"Part of the Conversation": A Qualitative Study of Oncology Healthcare Professionals' Experiences of Integrating Standardized Assessment and Documentation of Complementary Medicine

Introduction:

The use of complementary medicine (CM) among individuals with cancer is common, however, it is infrequently assessed or documented by oncology healthcare professionals (HCPs). A study implementing standardized assessment and documentation of CM was conducted at a provincial cancer agency. The purpose of this study was to understand the perspectives and experience of oncology HCPs who took part in the study, as well as withdrew, regarding the feasibility and the challenges associated with assessment and documentation of CM use.

Methods:

An interpretive descriptive study methodology was used. A total of 20 HCPs who participated, managed staff, or withdrew from the study were interviewed. Interviews were recorded and transcribed verbatim. Thematic, inductive analysis was used to code and analyse themes from the data.

Results:

Oncology HCPs who participated in the study felt that CM use was common among patients and recognized it went underreported and was poorly documented. Facilitating factors for the implementation of standardized assessment and documentation of CM use included having a standard assessment form, embedding assessment within existing screening processes, and leveraging self-report by patients. Barriers included limited time, perceived lack of knowledge regarding CM, hesitancy to engage patients in discussion about CM, and lack of institutional support and resources. Recommendations for future implementation included having explicit policies related to addressing CM at point-of-care, leveraging existing electronic patient reporting systems, including the electronic health record, and developing information resources and training for HCPs.

Conclusions:

With the high prevalence of CM use among individuals with cancer, oncology HCPs perceive addressing CM use to be feasible and an essential part of high-quality, person-centered cancer care. Institutional and professional challenges, however, must be overcome to support the assessment, documentation and discussion of CM in patient-HCP consultations.

Patient-sharing relationship between Chinese medicine doctors and other physicians: costs and outcomes of breast cancer survivorship care

PURPOSE

Breast cancer survivors represent a unique group of patients who need complex and continuous care after their cancer treatment. These patients often see several providers in various specialties. This study aimed to analyze how traditional Chinese medicine (TCM) integration within care networks of patients with breast cancer might be related to health care costs and patient outcomes under the National Health Insurance program in Taiwan.

METHODS

We enrolled all patients who underwent definitive mastectomy for newly diagnosed breast cancer between 2007 and 2015. We analyzed the presence of TCM physicians and the patient-sharing relationship between TCM physicians and other physicians during the first year after mastectomy. The outcomes included all-cause mortality, avoidable hospitalization, and medical expenditures.

RESULTS

There were 68,987 patients with breast cancer, with a median age of 53 years. After propensity score matching, patients whose TCM doctors had the highest connectedness with other physicians had the lowest odds of avoidable hospitalization (adjusted odds ratio 0.86; 95% confidence interval [CI], 0.78-0.96) and lowest hazard of mortality (adjusted hazard ratio, 0.82; 95% CI, 0.72-0.93), followed by those with TCM doctors with medium connectedness, then low connectedness, and lastly those patients with no TCM doctor in their care network.

CONCLUSIONS

A dose-response pattern was observed regarding the relationship between TCM doctor's connectedness with other physicians within a patient's care network and patient outcomes.

IMPLICATIONS FOR CANCER SURVIVORS

The findings demonstrated that stronger connectedness between TCM and other physicians could help improve the health outcomes of breast cancer survivors.

Anticancer agents and phytotherapy: Interactions that are often unrecognized

Phytotherapy is the main complementary medicine for which patients afflicted with cancer have recourse but the associated consumption of phytotherapy products gives rise to a risk of interaction with anticancer agents. The aim of this prospective study was to measure the prevalence of the consumption of phytotherapy products as well as their interactions with anticancer agents in a cohort of patients from January 2018 to August 2019. Patients hospitalized in the conventional hematology unit and outpatients who had their prescriptions for oral anticancer agents filled at the hospital pharmacy were questioned about consumption of phytotherapy products by pharmacy externs trained in pharmaceutical interviews. Among the 110 hospitalized patients who answered the questionnaire, 40% (n = 44) used phytotherapy and 5 of them continued to consume it during the cycles of injectable chemotherapy. As a result, 10 interactions were found between the plants and the anticancer agents (prevalence of 27%). Among the 59 outpatients, 17% (n = 10) consumed phytotherapy. Eight interactions were identified (prevalence of 80%). The potential consequences were an increase or a decrease in the concentration of the anticancer agents and an increase in the risk of bleeding, hepatoxicity, and hypokalemia. The consumption of phytotherapy was unknown by a health professional for 44% of hospitalized patients and 60% of the outpatients. The risk of interactions between plants and anticancer agents is not negligible and professionals should be cognizant of this in their daily practice. The availability of tools for training and detection of interactions is indispensable for managing patients undergoing onco-hematology treatments.

Facilitators and barriers to traditional medicine use among cancer patients in Malawi

BACKGROUND

Increasing access to conventional cancer treatment (CT) in low-income countries (LICs) is an important public health initiative to address the global burden of cancer. However, LICs have a high prevalence of use of traditional and complementary medicine (T&CM). It is important to consider the factors that influence a patient's choice to use T&CM, CT, or both for their cancer treatment.

METHODS

We conducted focus groups among adult cancer patients in Lilongwe, Malawi to identify facilitators and barriers of T&CM use. Focus groups were recorded, transcribed, translated, and underwent thematic content analysis.

RESULTS

Cultural norms, T&CM access, T&CM success, and CT failure were all identified as facilitators to T&CM use. CT success and T&CM failure were identified as barriers. Access and norms appear to determine initial treatment selection, while treatment outcomes dictate continued use of T&CM or CT.

CONCLUSION

This study identified a pragmatic and experience-based treatment selection process that aligns with the social cognitive theory of behavior and assists in comprehending the factors that influence T&CM use among cancer patients in a low resource setting.

Prevalence of traditional, complementary, and alternative medicine use by cancer patients in low income and lower-middle income countries

The use of traditional, complementary, and alternative medicine (TCAM) for cancer may influence the delivery or effectiveness of conventional cancer treatment. In this systematic review, we aimed to (1) summarise the available prevalence data on traditional medicine use by cancer patients in less developed countries (LDCs), and (2) stratify the prevalence data by world region and country income level. A literature search for cancer, TCAM, and low income (LI) and lower-middle income (LMI) countries was conducted across 5 databases. A total of 2,365 publications were reviewed for eligibility, of which 25 studies met inclusion criteria. The combined sample size was 6,878 cancer patients, with a median of 54.5% reporting the use of TCAM for cancer care. Of the studies providing data on the concomitant use of TCAM and conventional cancer treatment (n = 4,872 cancer patients), a median of 26.7% of participants reported combining the two systems of medicine. From the data available, it is apparent that TCAM use among cancer patients in less developed countries is common; however, additional studies are needed to support the safe and effective management of cancer for patients in LI and LMI countries.

Safety and Efficacy of Herbal Sedatives in Cancer Care

Insomnia and other sleep disturbances are common in cancer patients. Insomnia is a multifactorial health concern that currently affects at least 1 in 3 cancer patients, and yet most insomnia sufferers do not consult their physician regarding pharmaceutical options for relief. Use of hypnotic drugs (primarily benzodiazepines) is associated with increasing tolerance, dependence, and adverse effects on the central nervous system. While hypnotic drug use declined substantially in the past decade, the use of herbal sedatives appeared to increase. Mostly self-prescribed by lay people, herbal sedatives hold widespread appeal, presumably because of their lower cost and higher margin of safety when compared to pharmaceuticals. Studies of better-known herbal sedatives, notably valerian and kava, showed moderate evidence for both safety and efficacy for valerian while revealing disturbing toxicity concerns for kava. Milder sedatives or anxiolytics in need of clinical study include German chamomile, lavender, hops, lemon balm, and passionflower; St. John’s wort may have anxiolytic effects with relevance to sleep. Herb-drug interactions are a possibility for some of these species, including St. John’s wort. Although sufficient evidence exists to recommend some of these agents for short-term relief of mild insomnia, long-term trials and observational studies are needed to establish the safety of prolonged use as well as overall efficacy in the context of cancer treatment and management.

Phytoestrogens in Botanical Dietary Supplements: Implications for Cancer

Phytoestrogens are plant constituents that possess either estrogenic or antiestrogenic activity. Although their activities are weak as compared with human endogenous estrogens, the consumption of phytoestrogens may have clinically significant consequences. A number of botanicals, or the compounds contained therein, have been identified as putative estrogenic agents, but consensus in the biomedical community has been hampered by conflicting data from various in vitro and in vivo models of estrogenic activity. Phytoestrogens may serve as chemopreventive agents while at the same time being capable of promoting growth in estrogen receptor positive cancer cell lines. Furthermore, they may exert their estrogenic influence through receptor-dependent and/or receptor-independent mechanisms. These findings have led to speculation that phytoestrogen intake might be ill advised for patients at an increased risk for hormone-dependent cancers, cancer patients, or cancer survivors. This article will attempt to sort out discrepancies between various experimental models and establish whether certain herbs possess estrogenic activity. The review will focus on 5 popular botanical dietary supplements: Trifolium pratense (red clover), Cimicifuga racemosa (black cohosh), Humulus lupulus (hops), Angelica sinensis (dong quai), and Glycyrrhiza glabra (licorice). It will address their mechanisms of action, clinical evidence bases, and implications for use in cancer.

Valerian: no evidence for clinically relevant interactions

In recent popular publications as well as in widely used information websites directed to cancer patients, valerian is claimed to have a potential of adverse interactions with anticancer drugs. This questions its use as a safe replacement for, for example, benzodiazepines. A review on the interaction potential of preparations from valerian root (Valeriana officinalis L. root) was therefore conducted. A data base search and search in a clinical drug interaction data base were conducted. Thereafter, a systematic assessment of publications was performed. Seven in vitro studies on six CYP 450 isoenzymes, on p-glycoprotein, and on two UGT isoenzymes were identified. However, the methodological assessment of these studies did not support their suitability for the prediction of clinically relevant interactions. In addition, clinical studies on various valerian preparations did not reveal any relevant interaction potential concerning CYP 1A2, 2D6, 2E1, and 3A4. Available animal and human pharmacodynamic studies did not verify any interaction potential. The interaction potential of valerian preparations therefore seems to be low and thereby without clinical relevance. We conclude that there is no specific evidence questioning their safety, also in cancer patients.

Chimonanthus nitens var. salicifolius Aqueous Extract Protects against 5-Fluorouracil Induced Gastrointestinal Mucositis in a Mouse Model

Gastrointestinal mucositis is a major side effect of chemotherapy, leading to life quality reduction in patients and interrupting the therapy of cancer. Chimonanthus nitens var. salicifolius (CS) is a traditional Chinese herb for enteral disease. Considering the protective effect of CS on intestine, we hypothesize that the aqueous extract of CS could be benefcial to gastrointestinal mucositis. To verify this, a mouse mucositis model was induced by 5-Fluorouracil (5-Fu). Male Balb/C mice were treated with CS aqueous extract (5, 10, and 20 g/kg) or loperamide (0.2 mg/kg) intragastrically for 11 days, and the severity of mucositis was evaluated. Furthermore, the chemical compounds of CS aqueous extract were also analysed by high-performance liquid chromatography (HPLC). Our results demonstrated that CS aqueous extract improved mice body weight, diarrhoea, and faecal blood, maintained the liver function and intestinal length, alleviated villus shortening, and suppressed the apoptosis and inflammation in small intestine. We concluded that CS could protect mice against 5-Fu induced mucositis by inhibiting apoptosis and inflammation, and this protective effect might be associated with the 3 flavonoids (rutin, quercetin, and kaempferol) identified in CS aqueous extract.

Evaluation of documented drug interactions and contraindications associated with herbs and dietary supplements: a systematic literature review

BACKGROUND AND AIMS

The use of herbs and dietary supplements (HDS) alone or concomitantly with medications can potentially increase the risk of adverse events experienced by the patients. This review aims to evaluate the documented HDS-drug interactions and contraindications.

METHODS

A structured literature review was conducted on PubMed, EMBASE, Cochrane Library, tertiary literature and Internet.

RESULTS

While 85 primary literatures, six books and two web sites were reviewed for a total of 1,491 unique pairs of HDS-drug interactions, 213 HDS entities and 509 medications were involved. HDS products containing St. John's Wort, magnesium, calcium, iron, ginkgo had the greatest number of documented interactions with medications. Warfarin, insulin, aspirin, digoxin, and ticlopidine had the greatest number of reported interactions with HDS. Medications affecting the central nervous system or cardiovascular system had more documented interactions with HDS. Of the 882 HDS-drug interactions being described its mechanism and severity, 42.3% were due to altered pharmacokinetics and 240 were described as major interactions. Of the 152 identified HDS contraindications, the most frequent involved gastrointestinal (16.4%), neurological (14.5%), and renal/genitourinary diseases (12.5%). Flaxseed, echinacea, and yohimbe had the largest number of documented contraindications.

CONCLUSIONS

Although HDS-drug interactions and contraindications primarily concerned a relatively small subset of commonly used medications and HDS entities, this review provides the summary to identify patients, HDS products, and medications that are more susceptible to HDS-drug interactions and contraindications. The findings would facilitate the health-care professionals to communicate these documented interactions and contraindications to their patients and/or caregivers thereby preventing serious adverse events and improving desired therapeutic outcomes.

Optimizing chemotherapy: concomitant medication lists

Identifying sources of variability in the response to cancer chemotherapy requires knowledge of all variables, including concomitant medications, that can alter the metabolism and pharmacokinetics of chemotherapy. This study investigated the accuracy of the lists of concomitant medications in the charts of cancer patients. Information collated from a questionnaire, patient interview, and the patient's medical chart was used to obtain validated medication lists. Patients took an average of 4.8 prescription drugs, 1.6 nonprescription drugs, and 1.6 other remedies within the 3 days prior to chemotherapy. Of the concomitant drugs actually taken, the medical records did not report 24% of prescription drugs, 84% of nonprescription drugs, and 83% of other remedies. Electronic medical records (EMRs) were more complete than paper charts, but even these omitted >75% of nonprescription drugs and other remedies. Potential drug interactions were noted in this study. This study documents the extent and complexity of the concomitant drugs taken by patients undergoing chemotherapy and the deficiencies in recording this information in medical charts.

Dietary supplement use in cancer care: help or harm

Conventional wisdom generally recommends complete avoidance of all dietary supplements, especially during chemotherapy and radiation. This interdiction persists, in spite of high rates of dietary supplement use by patients throughout all phases of cancer care, and can result in patients' perceptions of physicians as negative, thus leading to widespread nondisclosure of use. A review of the clinical literature shows that some evidence for harm does exist; however, data also exist that show benefit from using certain well-qualified supplements. Physicians should increase their knowledge base about dietary supplement use in cancer and consider all of the data when advising patients. Strategies that are patient-centered and reflect the complete array of available evidence lead to more nuanced messages about dietary supplement use in cancer. This should encourage greater disclosure of use by patients and ultimately increase safety and efficacy for patients choosing to use dietary supplements during cancer care.

A strategy for controlling potential interactions between natural health products and chemotherapy: a review in pediatric oncology

The high prevalence of complementary and alternative medicine use including natural health products (NHPs) in the pediatric oncology population is well established. The potential for concurrent use of NHPs with conventional chemotherapy necessitates physician awareness regarding the potential risks and benefits that might come from this coadministration. Knowledge of interactions between NHPs and chemotherapy is poorly characterized; however, an understanding of potential mechanisms of interaction by researchers and clinicians is important. Concerns regarding the use of antioxidants during chemotherapy are controversial and evidence exists to support both adherents and detractors in this debate. Our review addresses issues regarding potential interactions between NHPs and chemotherapies used in pediatric oncology from a pharmacokinetic and pharmacodynamic perspective. Examples of combinations of NHP and chemotherapies are briefly presented in addition to a strategy to avoid (or induce) a possible interaction between a NHP and chemotherapy. In conclusion, more clinical research is needed to substantiate or preclude the use of NHPs in the treatment of cancer and especially in combination with chemotherapy.

Complementary and alternative medicine in pediatric oncology

Children with cancer and their families use complementary and alternative medicine (CAM) to reduce symptoms, cope with life-threatening illness, and improve overall well-being. Despite numerous published surveys on the use of CAM in pediatric oncology, few studies have tested CAM therapies for safety and efficacy. A growing body of literature in adult oncology provides evidence for the role of CAM to help manage symptoms and reduce distress. Translating this research to children requires studies with new models that address family roles and include measurement of outcomes relevant to children's developmental stages and unique responses. One of the limitations in pediatrics is the small samples available to single institutions. Conducting clinical trials through the cooperative group mechanism is one way of obtaining sufficient sample sizes to determine effectiveness and safety of CAM therapies. This article summarizes research to date and describes a beginning approach to measuring outcomes of supportive CAM therapies in children with cancer.

The Incidence of Potential Interactions Between Dietary Supplements and Prescription Medications in Cancer Patients at a Veterans Administration Hospital

OBJECTIVE

The concurrent use of dietary supplements and prescription medications is common among patients with cancer. This study examines potential interactions between dietary supplements and prescription medications in a Veteran Hospital cancer population.

METHODS

Eligible patients seen at the Hematology/Oncology clinic at the Veterans Administration Medical Center in Cincinnati, OH, were administered a survey to determine their use of dietary supplements. Medication profiles were compiled from patients' medical charts and pharmacy records. It was also noted whether supplementation was previously documented. Potential interactions between dietary supplements and prescription medications were identified from a literature search of documented interactions. Several demographic factors, including age, race, marital status, education and income, were assessed for differences between patients found to be at risk for interactions and those for whom no risks were identified.

RESULTS

Dietary supplements were used by 61% of patients. Multivitamins were the most common supplement (80.3%) followed by minerals (40.6%) and herbal preparations (24.8%). Of the 121 patients taking supplements, 65 patients (54%) reported taking more than one. A potential risk for interaction between dietary supplement and prescription medication was identified in 12% of patients taking supplementations. Three patients were at risk for multiple interactions. Veterans who were not currently married were more likely to be at risk for interactions (P = 0.024). Only 28% of patients taking dietary supplements had this supplementation documented in their medical record.

CONCLUSION

Dietary supplementation by a veteran cancer population is common. Interactions between the supplement and prescription medication is a potential problem. Patient-physician discussion and documentation of these issues should be systematically addressed.

The potential impact of the use of homeopathic and herbal remedies on monitoring the safety of prescription products

The purpose of this paper is to explore the possibility that adverse reactions and drug interactions arising from the use of homeopathic and herbal medicines could lead to confusion when adverse reactions to conventional medicines are reported. An extensive literature review was conducted on the occurrence of adverse reactions and drug interactions following the use of homeopathic or herbal remedies, and the potential for these to confound adverse event reporting to conventional medicines considered. The survey demonstrates the potential for herbal remedies and homeopathic products, to produce adverse drug reactions or drug interactions, and shows the scope for potential for confusion with those arising from conventional medicines. There is a need for greater awareness that adverse reactions apparently due to a conventional medicine, might in reality be due to a herbal medicine or a drug interaction between a herbal medicine and a conventional drug, particularly when a health professional is unaware of the extent of a patient's self-medication with alternative therapies.

Drug interactions in oncology

Drug interactions are an ongoing concern in treatment of cancer, especially when cytotoxic drugs are being used. However, the clinical relevance of these interactions is not always investigated. Drug interactions can be pharmaceutical, pharmacokinetic, or pharmacodynamic. They can also be wanted (eg, use of ciclosporin to enhance the oral bioavailability of paclitaxel); unwanted (eg, combination of the antiviral agent sorivudine and oral fluorouracil analogues can lead to fatal complications); between cytotoxic drugs, cytotoxic drugs and non-cytotoxic drugs; or with pharmaceutical vehicles. Potential interactions between anticancer drugs and over-the-counter or alternative medicines and herbs should not be underestimated. More attention should be given to the recognition of potential drug interactions in the preclinical and early clinical development phase of a new anticancer drug. Here, we provide a comprehensive overview of drug interactions, with selected examples.

Detoxifying cancer causing agents to prevent cancer

Different vitamins and other micronutrients in vegetables, fruits, and other natural plant products may prevent cancer development (carcinogenesis) by interfering with detrimental actions of mutagens, carcinogens, and tumor promoters. The goal of current studies in cancer prevention is to determine the mechanisms of synergistic action of the natural source compounds known to inhibit one or more stages of carcinogenesis, that is, initiation and promotion/progression. Many natural cancer preventive agents are effective inhibitors of tumor initiation, promotion, and/or progression. The mechanism of action is related to their abilities to prevent critical carcinogen metabolism and to increase detoxification of carcinogens and tumor promoters. The authors review here the potential role of the detoxification system and, in particular, the roles of D-glucaric acid and the enzyme beta-glucuronidase in early detection and prevention of cancer. There is now growing evidence for the possible control of different stages of the cancer induction by inhibiting beta-glucuronidase with D-glucaric acid derivatives, especially with its salts (D-glucarates). D-Glucaric acid has been found in many vegetables and fruits. Therefore, the consumption of fruits and vegetables naturally rich in D-glucaric acid or self-medication with D-glucaric acid derivatives such as calcium D-glucarate offers a promising cancer prevention approach.

Panax ginseng: a role in cancer therapy?

Panax ginseng is a plant that has been used in traditional medicine in China for thousands of years. It is used as a general tonic or adaptogen with chronically ill patients and is frequently featured in traditional medicine prescriptions from China, Japan, and Korea used by cancer patients. The putative active compounds are the ginsenosides, of which there are more than two dozen. These compounds are found in both Panax ginseng and in other Panax species that are used in herbal medicine. Analysis of ginsenosides is being used in developing quality control assessments for ginseng, which has frequently been adulterated due to its high cost; many currently available standardized extracts do appear to contain the amounts of ginsenosides listed on package labeling. The toxicity of ginseng appears to be low: some of the reports of toxic episodes of ginseng may actually pertain to other components of multicomponent preparations. Very low incidence of toxicity has been observed in ginseng clinical trials using well-characterized preparations. Numerous pharmacological activities of ginseng and the ginsenosides have been explored: the authors review here the activities relating to cancer. Immune system modulation, antistress activities, and antihyperglycemic activities are among the most notable features of ginseng noted in laboratory and clinical analyses. Much testing has been done in humans to explore ginseng's purported antifatigue properties, but this area remains controversial. A number of investigations point to antitumor properties and other pharmacological activities related to cancer, but no trials have yet confirmed a clinically significant anticancer activity. Cancer patients may empirically find ginseng to be useful when they are fatigued, although clinical trials should be conducted to confirm its benefits.

Drug Interactions Between Herbal and Prescription Medicines

Until reports of interactions between St John's wort and drugs such as digoxin, warfarin, protease inhibitors and oral contraceptives began to appear, very few herb-drug interactions were documented. These are now becoming more common, although still rare compared with drug-drug interactions. In the absence of hard data, potential interactions are being highlighted, and this review attempts to distinguish between the speculative and the proven. The subject is approached from a therapeutic point of view since in most cases the patient is already taking one or more prescription drugs, and the question is whether or not it is safe for a particular herb to be added to the regimen. Although many of the examples of herb-drug interactions are minor or theoretical at present, the fact remains that some are serious and life threatening, and these almost exclusively concern cyclosporin, anticoagulants, digoxin, antidepressants and protease inhibitors, taken with the herb St John's wort. Ginkgo and ginseng are implicated in a number of reports, but many of these are unsubstantiated. To date, the cardiovascular, central nervous and immune systems are the most common therapeutic categories cited in the literature and other than those, examples are very limited. Although many herbal drugs have good safety profiles, it must be borne in mind that herbal supplements are intended to be taken over an extended period of time, which provides the opportunity for enzyme induction and other mechanisms of interaction to take effect.