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英國 癌症患者使用草藥的情況

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Nature 英國癌症臨床研究雜誌 2011 年 3 月 1 日

癌症患者使用草藥的情況:橫斷麵調查

https://www.nature.com/articles/bjc201147

S Damery s.l.damery@bham.ac.uk

初級保健臨床科學,伯明翰大學健康與人口科學學院,埃德巴斯頓,伯明翰,B15 2TT,英國
英國癌症雜誌第 104 卷,第 927-933 頁(2011 年)

摘要
背景:
據估計,很大一部分癌症患者使用草藥,但缺乏證實這一點的數據。本研究旨在調查西米德蘭茲癌症患者使用草藥的普遍性,並確定預測草藥使用的特征。

方法:
對考文垂一家醫院接受隨訪的腫瘤患者(n=1498)進行了橫斷麵調查。調查對象被問及自診斷出癌症以來的草藥使用情況,並評估了社會人口統計學和癌症相關特征與草藥使用之間的關聯。

結果:
共收到 1134 份回複(75.7%)。草藥使用率為 19.7%(95% CI:17.4–22.1;n=223)。使用者更有可能是富裕的、女性和 50 歲以下的人。自診斷出癌症以來,草藥使用量隨時間增加(趨勢 X2=4.63;P=0.031)。驗證數據集來自對伯明翰具有不同社會經濟特征的腫瘤患者(n=541)的調查,結果顯示估計患病率沒有顯著差異(16.6%;95% CI:11.9–22.2)。

結論:
大量癌症患者可能正在服用草藥。如果醫療保健專業人員要支持治療依從性並避免不必要的藥物相互作用,了解這些人的自我用藥行為至關重要。

討論
幾乎五分之一的受訪者表示,自診斷出癌症以來,他們使用過草藥。根據年齡和性別對這一患病率進行標準化,得出的標準化患病率估計為 16.8%。目前,英國約有 200 萬人患有癌症,這意味著英國約有 336,000 名癌症患者經常使用草藥。

通過專門關注草藥,而不是將其歸入補充和替代療法這一更寬泛的術語,本研究補充了英國癌症患者使用草藥的現有文獻(Gratus 等人,2009a)。許多此類研究涉及的參與者人數很少,因此無法提供草藥使用量的精確估計(Rees 等人,2000 年)。我們的調查回複率很高,樣本量很大(75.7%;n=1134)。這些發現具有表麵效度,與其他研究結果相吻合,這些研究發現,女性、年輕群體和較富裕人群是癌症患者中最有可能使用草藥的亞群(Ernst 和 Cassileth,1998 年;Harris 等人,2003 年;Catt 等人,2006 年)。除了草藥外,很大一部分使用者還可能使用其他補充和替代療法,例如維生素、礦物質補充劑、順勢療法或其他療法,例如芳香療法或按摩。

雖然有些草藥僅供特定癌症類型的患者使用,例如鋸棕櫚 (Serenoa serrulata) 僅供男性生殖器癌症患者使用 (Olaku and White, 2010),但我們的受訪者通常將草藥用於治療各種癌症類型,這表明大多數草藥似乎並非針對特定的癌症部位,但可能出於多種原因使用,例如減輕與癌症或其治療相關的症狀,或治療相關疾病或合並症。

與其他研究一樣,我們發現乳腺癌女性患者特別可能使用草藥,生殖器癌症女性也是如此,盡管在多變量分析中,癌症部位並不是草藥使用的重要預測因素。這可能反映了這樣一個事實:對於某些癌症類型,可用的草藥可能有限,特別是當患者正在接受治療或處於治療後階段時,如果要尋求這些草藥來緩解特定病症或副作用。我們還發現,癌症患者使用草藥的可能性隨著診斷時間的延長而增加。診斷後前兩年使用率較低是合理的,因為患者此時可能正在接受常規治療,例如放療或化療。治療後幾年使用率較高可能表明患者更有可能考慮使用草藥來解決癌症治療的長期後果。這表明,可能不需要像通常所說的那樣擔心與常規治療可能產生的有害相互作用(McCune 等人,2004 年)。然而,有記錄顯示,一些草藥與其他常規藥物存在相互作用,例如華法林(Ali 和 Hussain-Gambles,2005 年)或他莫昔芬(Werneke 等人,2004b 年),那些服用處方藥治療其他合並症的人在使用草藥時可能會遇到有害的相互作用。

重要的是,持續治療的患者和癌症幸存者都可以獲取有關草藥及其安全性和有效性的信息資源。此外,如果患者在疾病複發後需要進一步治療,那麽此時可能已經確定使用草藥。常規臨床詢問應包括所有治療期之前的草藥使用情況。

局限性
本研究有幾個局限性。首先,依賴患者報告的草藥使用情況的患病率調查可能會受到回憶偏差的影響。這可能是故意的,因為癌症患者可能不會透露草藥的使用情況,特別是如果他們沒有告訴治療他們的醫療保健專業人員他們可能正在使用的任何草藥或補充劑(Evans 等人,2007 年;Saxe 等人,2008 年)。回憶偏差也可能是無意的,患者可能不記得自診斷出癌症以來他們是否服用過草藥,因此會少報或多報他們的草藥使用情況。關於保密問題,患者被告知,所有調查回複都將保密,並且他們的醫療團隊成員不會看到他們在調查中提供的任何信息。

第二,

偏倚可能意味著我們低估或高估了研究人群中癌症患者使用草藥的普遍性。雖然調查中白人和非白人的比例大致代表了英格蘭腫瘤患者的種族組合(國家癌症情報網絡,2009 年),但調查的受訪者更有可能是富裕、年長的白種人。但是,通過將我們的患病率估計值標準化為英格蘭癌症患者人群的年齡和性別,我們得出了癌症幸存者使用草藥的可靠估計值。

為了最大限度地減少痛苦風險,已知患有絕症的患者或負責的顧問認為可能因收到調查而感到痛苦的患者被排除在郵寄範圍之外。這一群體可能更有可能使用草藥來幫助他們應對所經曆的壓力,因此我們低估了癌症患者使用草藥的總體流行率。然而,我們沒有證據支持或反駁這種可能性。

最後,我們的調查是在一家醫院對個人進行隨訪的情況下進行的,這可能會影響調查結果的更廣泛的普遍性。然而,除了年齡和性別標準化的好處之外,在伯明翰一家醫院以較小規模重複調查所得的比較數據也增加了我們的研究結果的有效性,該調查涉及具有非常不同社會人口特征的患者群體。尤其是考慮到盡管比較人群包括更大比例的老年患者、更多的男性、更多的非白人族裔患者以及比 UHC&W 中的人群更多的社會經濟貧困患者,但較大規模調查的患病率與比較人群中觀察到的患病率之間沒有統計學上顯著差異(19.7%;95% CI:17.4–22.1 vs 16.6%;95% CI:11.9–22.2;P=0.292)。

nature  british journal of cancer  clinical study   

The use of herbal medicines by people with cancer: a cross-sectional survey

https://www.nature.com/articles/bjc201147

S Damery  s.l.damery@bham.ac.uk

  • Primary Care Clinical Sciences, School of Health and Population Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

British Journal of Cancer volume 104, pages927–933 (2011)

Abstract

Background:

A large proportion of cancer patients are estimated to use herbal medicines, but data to substantiate this are lacking. This study aimed to investigate the prevalence of herbal medicine use among cancer patients in the West Midlands, and determine the characteristics predicting herbal medicine use.

Methods:

A cross-sectional survey of oncology patients (n=1498) being followed up at a hospital in Coventry was undertaken. Recipients were asked about herbal medicine use since their cancer diagnosis, and the association between sociodemographic and cancer-related characteristics and herbal medicine use was evaluated.

Results:

A total of 1134 responses were received (75.7%). The prevalence of herbal medicine use was 19.7% (95% CI: 17.4–22.1; n=223). Users were more likely to be affluent, female, and aged under 50 years. Usage increased with time since cancer diagnosis (X2 for trend=4.63; P=0.031). A validation data set, derived from a survey of oncology patients in Birmingham (n=541) with differing socioeconomic characteristics showed no significant difference in estimated prevalence (16.6%; 95% CI: 11.9–22.2).

Conclusion:

A substantial number of people with cancer are likely to be taking herbal medicines. Understanding the self-medication behaviours of these individuals is essential if health-care professionals are to support treatment adherence and avoid unwanted pharmacological interactions.

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Main

Between 9 and 81% of cancer patients are said to use at least one type of complementary or alternative therapy after their cancer diagnosis (Ernst, 2000Catt et al, 2006). In particular, self-medication with herbal medicines and other ‘natural’ substances is widespread and increasing in the United Kingdom (Werneke et al, 2004aAstin et al, 2006). It has been estimated that a large proportion of patients with cancer use herbal medicines. These may be taken to prevent or relieve some of the symptoms of the cancer itself (Ali and Hussain-Gambles, 2005); to help alleviate some of the side effects from cancer treatments, such as radiotherapy or chemotherapy (Vickers et al, 2006); to treat an associated condition, such as anxiety or depression, or to provide a sense of control or a feeling of active involvement in cancer treatment (Verhoef et al, 1999). However, estimates of the prevalence of herbal medicine use are inconsistent (varying from 3 to 25% of cancer patients), and the quality and scope of existing studies are limited (Ernst and Cassileth, 1998Gratus et al, 2009a). Research typically focuses on restricted patient cohorts and specific tumour sites; includes small numbers of participants, and uses heterogeneous methodologies and definitions of herbal medicines, which make it difficult to assess the precise extent of herbal medicine use by cancer patients (Crocetti et al, 1998). Herbal medicines are also frequently subsumed under the broader heading of complementary and alternative medicines, and their use assessed alongside other therapies, such as aromatherapy, reflexology, meditation, acupuncture, and homeopathy (Downer et al, 1994Corner et al, 2006).

Among cancer patients, users of herbal medicines tend to be female, younger, and have higher socioeconomic status than non-users (Harris et al, 2003). Disease-related factors, such as the type of cancer, stage of disease, and disease duration have also been found to be significant predictors of herbal medicine use (Miller et al, 1998), with women with breast cancer most likely to use herbal medicines in comparison with the general population, and compared with those with other cancer types (Morris et al, 2000). However, studies of breast cancer patients and herbal medicine use constitute the majority of research literature, and may not be representative of other cancer diagnostic groups (Molassiotis et al, 2005).

Alongside increased interest in the use of herbal medicines by people with cancer, there has been a rise in concern about the safety of these treatments (Balneaves et al, 1999). Herbal medicines are often seen as more natural, and therefore safer than conventional treatments, and it is generally believed that they carry little potential for harm (Corner et al, 2006Vickers et al, 2006). However, in some cases, herbal medicines can present significant risks (Gratus et al, 2009a2009b). They may affect adherence with prescribed treatments, cause harmful interactions with conventional medications, reduce treatment efficacy, or lead to adverse events (Frye et al, 2004Catt et al, 2006Medicines and Healthcare Products Regulatory Agency, 2007). A recent systematic review of herbal medicine use by cancer patients identified 21 case reports of toxic effects and adverse events in users of herbal medicines (Olaku and White, 2010). As a result of the possibility of interactions between herbal medicines and conventional treatments, people with cancer are encouraged to advise health-care professionals if they are taking any type of medication, including herbal medicines and other supplements (Cancer Backup, 2010), although studies suggest that few patients do so (Corner et al, 2006).

Given the potential risks, and the lack of data to substantiate the use of herbal medicines by cancer patients in the United Kingdom, there is a need to better understand the prevalence of herbal medicine use among cancer patients, as well as improving knowledge of which herbal medicines patients use. This is an important first step in the development of accessible, authoritative, and independent information resources about herbal medicines and cancer, which are currently lacking in the United Kingdom (Gratus et al, 2009b). The aim of this study was to investigate the prevalence of herbal medicine use among people with cancer in the West Midlands, and to determine the sociodemographic and cancer-related characteristics that may predict herbal medicine use within this group.

Materials and methods

Study design and setting

This study used a cross-sectional survey, distributed by post, to oncology patients being followed up at University Hospitals Coventry and Warwickshire NHS Trust (UHC&W).

Participants and recruitment

Subsequent to securing permission from consultants responsible for the care of patients, the hospital information system was interrogated to identify a sample of eligible patients aged 18 and over, at least 6 months and no >5 years after a diagnosis of invasive cancer (between 1 April 2004 and 30 June 2009), who had been treated with curative intent. A total of 1507 potential participants were identified. The responsible consultant examined the list of potential participants to verify that the patient had been treated for invasive cancer and had been diagnosed within the specified time frame. Patients known to be terminally ill, or whom the consultant believed may be distressed by receipt of the survey for any other reason, were excluded from the sample to minimise the possibility of distress, as were any individuals whose records did not indicate a consultant; duplicate records; those for whom a valid postal address could not be identified, and those who had died in the period between sample identification and survey mailing.

After exclusions had been made, 1498 eligible patients were sent a letter of invitation, a patient information sheet and a survey, to be returned to the research team at University of Birmingham via a FREEPOST envelope, also enclosed. This sample size assumed a prevalence of herbal medicine use among cancer patients of between 7 (Corner et al, 2006) and 13% (Harrison et al, 2004), and that a 60% response rate would yield 900 responses. This sample would be of sufficient size to determine the overall prevalence of herbal medicine use among respondents with a precision of 2% (95% confidence interval). Survey recipients who had not responded to the initial mailing after 2 weeks received one reminder.

Survey

Survey content was informed by the findings of a systematic review of the literature relating to herbal medicine use by cancer patients in the United Kingdom (Gratus et al, 2009a). The survey included closed questions on sociodemographic characteristics (age, gender, and ethnicity), cancer-related characteristics (year of diagnosis), and a number of categorical (yes/no response) questions relating to the use of herbal medicines, vitamin/mineral supplements and homeopathic remedies; the sources through which herbal medicines were obtained by users (e.g., bought on the high street, from a herbal medicine practitioner, purchased via the Internet), and the use of specific herbal medicines since diagnosis, detailed in a pre-coded ‘tick-list’, derived from a review of the most commonly cited herbal medicines from existing research literature. Patients were able to select multiple herbal medicines if they had used more than one. They were also able to list any additional herbal medicines that they had used since diagnosis, which were not included in the pre-coded list, using a free-text response box.

Data analysis

Analysis focused on the sociodemographic and cancer-related characteristics of respondents, and their association with herbal medicine use. In addition to the data obtained from respondents via their survey responses, anonymised hospital records for each respondent were used to derive information related to cancer type, classified according to International Classification of Diseases (ICD-10) categories for invasive cancer (World Health Organization, 1994), and postcode data were used to derive a deprivation score, which was converted into a deprivation quartile using the 2007 Indices of Multiple Deprivation: quartile 1=most affluent; quartile 4=most deprived (Department of Communities and Local Government, 2007).

An individual was defined as a herbal medicine user if they answered ‘yes’ to the question: ‘have you used herbal remedies since your cancer was diagnosed?’ and/or gave a positive response to any question asking about herbal medicine purchasing, and/or indicated the use of a specific herbal medicine from the pre-coded list or via the free-text response box. Free-text responses were coded and analysed in the same way as herbal medicines indicated in the tick-list. Chi-squared tests and binary logistic regression were used to compute bivariate and multivariate odds ratios (ORs) to evaluate the association between sociodemographic and cancer-related characteristics and herbal medicine use, and to assess the factors predictive of herbal medicine use by patients with cancer. In order to test for responder bias, age, gender, ethnicity, deprivation, and time since diagnosis distributions for respondents and non-respondents were compared using χ2 tests. Prevalence rates of herbal medicine use were age and gender standardised to the cancer patient population in England using the 2006 cancer registration statistics (Office for National Statistics, 2006). All data were analysed using SPSS (version 15.0, SPSS Inc., Chicago, IL, USA).

Validation data set

As the survey population was identified from the records of one hospital only, the survey was repeated on a smaller scale at another hospital in Birmingham (541 patients mailed), in order to validate the rates of herbal medicine use identified from survey respondents treated at UHC&W and assess the wider generalisability of the findings. Patients were identified at the participating hospital in Birmingham in the same way as for the larger survey, according to the same eligibility criteria, and received the same survey and study literature; however, non-responders did not receive a reminder.

Results

Of 1498 surveys distributed, 27 (1.8%) were returned blank, indicating that the recipient did not wish to receive a reminder. A further 337 survey recipients (22.5%) did not respond to either the initial or reminder mailings, giving a total of 1134 useable responses (response rate 75.7%), Figure 1.

Figure 1
 

figure 1

Consort diagram detailing surveys mailed and returned.

Some statistically significant differences were found between the sociodemographic and cancer-related characteristics of responders and non-responders. Those in the youngest age group (<50 years old) were significantly less likely to respond than those in older age groups (X2=21.28; P=<0.0001), and those of non-White ethnicity were less likely to respond than those in the White ethnic group (X2=105.48; P=<0.0001). Finally, those in the most deprived deprivation quartiles were significantly less likely to respond to the survey than those in more affluent quartiles (X2=45.61; P=<0.0001). There were no significant differences between responders and non-responders on the basis of gender (X2=1.87; P=0.172) or the number of years since a patient had received their diagnosis of cancer (X2=1.12; P=0.571).

Characteristics of respondents

The sociodemographic and cancer-related characteristics of respondents are shown in Table 1. The majority of respondents were female (n=821; 72.4%), and in the White ethnic group (n=1078; 95.1%). Patients aged between 60 and 69 years old constituted the largest group (n=382; 33.7%), with those aged under 50 forming the smallest respondent group (n=188; 16.6%). Patients in the two most affluent deprivation quartiles (quartiles 1 and 2) constituted 60.3% of respondents (n=681), compared with 15.6% of respondents (n=176) in the most deprived quartile. With regard to cancer-related characteristics, the greatest proportion of respondents had received their diagnosis of cancer between 2 and 4 years before the survey mailing (n=460; 40.6%). Patients with breast cancer constituted the largest group according to cancer type, accounting for over half of all respondents (n=585; 51.6%), followed by 14.1% with cancer related to the digestive organs (n=160), and male genital cancers (n=151; 13.3%). The least represented cancer types were amalgamated and categorised as ‘other’ cancers (n=23; 2.0%). This included primary bone cancer (n=1), soft tissue sarcomas (n=4), and cancers of the skin (n=3), urinary tract (n=12), eye, brain, and central nervous system (n=1), and cancers of unknown origin (n=2).

Table 1 Characteristics of respondents, herbal medicine use by characteristic and predictors of herbal medicine use

Prevalence of herbal medicine use

Across all respondents, the crude prevalence of herbal medicine use was 19.7% (95% CI: 17.4–22.1; n=223). The age and gender standardised prevalence rate, calculated using the 2006 cancer registrations statistics for England was 16.8%. A total of 282 patients had used vitamin supplements (24.9%), 258 had used mineral supplements (22.8%), 59 had used some form of homeopathic remedies (5.2%), and 176 had used other complementary and alternative therapies, such as aromatherapy or massage (15.5%).

Of the herbal medicine users (n=223), 55.2% (n=123) had used vitamin supplements in addition to herbal medicines, 49.3% (n=110) had used mineral supplements as well as herbal medicines, 21.5% (n=48) had also used homeopathic remedies, and 41.2% had used other complementary and alternative therapies. Six individuals (2.7%) reported using all of these.

Univariate analyses indicated that a greater proportion of female respondents reported using herbal medicines than males (n=183, 22.3% vs n=40, 12.8%), Table 1. Respondents in the White and non-White ethnic groups did not differ in their use of herbal medicines (n=212, 19.7% vs n=11, 19.6%). Respondents in the 50–59 year age group had the highest prevalence of herbal medicine use (n=61; 25.0%), as did those in the two most affluent deprivation quartiles (n=144; 21.1%). Patients who were >4 years since diagnosis had the highest rate of use (n=64; 24.1%), and patients with female genital cancers and breast cancer were most likely to be herbal medicine users (n=28; 24.6% vs n=133; 22.7%).

Predictors of herbal medicine use

Binary logistic regression was used to calculate bivariate OR to evaluate the association between sociodemographic or cancer-related respondent characteristics and herbal medicine use (Table 1). Users of herbal medicines were significantly more likely to be in the two most affluent deprivation quartiles in comparison with the most deprived quartile (quartiles 1 and 2, OR: 1.7; 95% CI: 1.1–2.7). A χ2 test for trend confirmed a decreasing likelihood of herbal medicine use with increasing deprivation (X2=4.13; P=0.042). Females were nearly twice as likely to be herbal medicine users as males (OR: 1.9, 95% CI: 1.4–2.8; P=<0.0001). Herbal medicine users were also more likely to be younger, with patients aged under 50 years old significantly more likely to use them than those in the 70+ age group (OR: 1.6; 95% CI: 1.0–2.5), and those aged between 50 and 59 having the highest likelihood of using herbal medicines (OR: 1.8; 95% CI: 1.2–2.7; P=0.006). There was no association between ethnic group and herbal medicine use.

With regard to cancer-related characteristics, people with breast cancer were most likely to be herbal medicine users, with all other cancer types except female genital cancers having a lower usage. Those with oral and respiratory cancers (including lip, oral cavity, head and neck and lung cancers) were significantly less likely than people with breast cancer to use herbal medicines (OR: 0.3; 95% CI: 0.1–0.9), as were patients with thyroid and lymphoid cancers (OR: 0.3; 95% CI: 0.1–0.8; P=0.016). Usage increased with time since diagnosis, with patients over 4 years since diagnosis the most likely to be herbal medicine users (X2 for trend=4.63; P=0.031).

Logistic regression was also used to calculate multivariate OR, with each variable in the model controlled for all other variables. All significant predictive factors for herbal medicine use observed in the bivariate analysis (affluence, younger age, longer time since diagnosis, and female gender) remained significant in the multivariate model, with the exception of cancer type.

Use of specific herbal medicines

All herbs detailed in the pre-coded survey list were used by at least one individual, with the exception of Ivy (Hedera helix), Table 2. Evening Primrose (Oenothera biennis) was the most frequently used herb (n=61; 27.4%), followed by Echinacea (Echinacea purpurea) (n=48; 21.5%) and Garlic (Allium sativum) (n=43; 19.3%). Breast cancer patients were the most likely to use each of the specified herbs, constituting 100% of users of Agnus castus (Vitex agnus castus), Dong quai (Angelica sinensis), Red vine leaf (Vitis vinifera), Wild Yam (Dioscorea villosa), and Willow (Salix alba). Of the other herbs, only Saw palmetto (Serenoa serrulata) was used exclusively by patients within one cancer type – in this case, all users (n=3) were in the male genital cancer group.

Table 2 Frequencies of use since diagnosis for specific herbal medicines, and use by cancer type

Patients were also given the opportunity to cite the use of other herbal medicines not detailed in the pre-coded list. Nineteen additional herbal medicines were reported in this way, of which only six were used by more than one individual: herbal teas (n=14); Aloe vera (Aloe barbadensis), (n=8); Arnica (Arnica montana), (n=6); Starflower (Borago officinalis), (n=4); Sage (Salvia officinalis), (n=3), and Turmeric (Curcuma longa), (n=3).

Where herbal medicines were obtained

The majority of herbal medicine users reported obtaining their herbal medicines from high street stores and supermarkets (n=151; 67.7%). Recommendation by a health-care professional was a frequent source of information (n=52; 23.3%), as was purchase of herbal medicines from the Internet or through mail order (n=51; 22.9%). Users were less likely to obtain herbal medicines following a consultation with a herbal practitioner; taken together, 18 unique individuals had consulted a practitioner of Western herbal medicine, Chinese/Ayurvedic herbal medicine, or a practitioner from another herbal medicine tradition (8.1%), Table 3.

Table 3 Herbal medicine users’ source of information and purchase

Validation data set

To validate the prevalence estimates for herbal medicine use obtained from patients of UHC&W, a further small-scale survey was undertaken involving people with cancer being followed up at a hospital in Birmingham. In all, 217 individuals responded to this survey from 541 mailed (response rate 40.1%). Respondents in Birmingham differed from respondents to the larger survey with regard to a number of characteristics. University Hospitals Coventry and Warwickshire NHS Trust respondents were significantly more likely to be female than those from Birmingham (OR: 1.5; 95% CI: 1.3–1.7; P=<0.0001). They were also twice as likely to be in the more affluent deprivation quartiles (OR: 2.1; 95% CI: 1.7–2.6; P=<0.0001), and were a younger population (X2=17.56; P=0.001). Respondents from UHC&W were less likely to be in the non-White ethnic group than those from Birmingham (OR: 0.5; 95% CI: 0.3–8.2; P=0.006).

The prevalence of herbal medicine use in the group from Birmingham was 16.6% (95% CI: 11.9–22.2; n=36). Despite the differences in the nature of the respondent populations to both surveys, there was no statistically significant difference in the prevalence of herbal medicine use between the two populations surveyed (X2=1.11; P=0.292).

Discussion

Almost one-fifth of our survey respondents reported using herbal medicines in the time since their diagnosis of cancer. Age and gender standardisation of this prevalence rate to the England cancer patient population gave a standardised prevalence estimate of 16.8%. With around two million people in the United Kingdom currently living with cancer, this could equate to approximately 336 000 individuals with cancer who are regular users of herbal medicines in the United Kingdom.

By focusing on herbal medicines specifically, rather than subsuming them under the broader term of complementary and alternative therapies, this study adds to the very limited existing literature regarding herbal medicine use by cancer patients in the United Kingdom (Gratus et al, 2009a). Many studies of this nature involve small numbers of participants and so cannot provide precise estimates of herbal medicine use (Rees et al, 2000). The response rate for our survey was high, and the sample size was large (75.7%; n=1134). The findings have face validity and fit well with other research, which has found that women, those in younger age groups, and those who are more affluent are the most likely subgroups of cancer patients to use herbal medicines (Ernst and Cassileth, 1998Harris et al, 2003Catt et al, 2006). A large proportion of users were likely to use other complementary and alternative therapies in addition to herbal medicines, such as vitamins, mineral supplements, homeopathic remedies, or other therapies, such as aromatherapy or massage.

Although some herbal medicines are used only by those with particular cancer types, such as Saw palmetto (Serenoa serrulata) used exclusively by patients with male genital cancers (Olaku and White, 2010), herbal medicines were typically used by our respondents across a range of cancer types, suggesting that the majority of herbs do not seem to be targeted towards specific cancer sites, but that they may be used for a range of reasons, such as the reduction of symptoms associated with the cancer or its treatment, or to address associated conditions or co-morbidities.

In common with other studies, we found that women with breast cancer are particularly likely to use herbal medicines, as are women with genital cancers, although in the multivariate analyses, cancer site was not a significant predictor of herbal medicine use. This may reflect the fact that for some cancer types, there may be limited herbal medicines available, particularly if these are being sought to alleviate specific conditions or side effects, either when patients are undergoing treatment or are in the post-treatment phase. We also found that the likelihood that people with cancer are using herbal medicines increases with time since diagnosis. Lower rates of use in the first 2 years after diagnosis are plausible because patients are likely to be undergoing conventional treatments, such as radiotherapy or chemotherapy at this time. Higher usage in the years following treatment may indicate that patients were more likely to consider using herbal medicines to address the long-term consequences of cancer treatment. This suggests that there may be less of a need to be concerned about possible harmful interactions with conventional treatments than is often asserted (McCune et al, 2004). However, there are documented interactions between some herbal medicines and other conventional medicines, such as warfarin (Ali and Hussain-Gambles, 2005) or tamoxifen (Werneke et al, 2004b), and those taking prescribed medication for other co-morbidities may experience harmful interactions when using herbal medicines.

It is important that information resources regarding herbal medicines and their safety and efficacy are available to both ongoing patients and to cancer survivors. Furthermore, if patients require further treatment, following recurrence of disease, for example, it is possible that herbal medicine use has become established by this time. Routine clinical questioning should encompass herbal medicine use before all treatment episodes.

Limitations

This study had several limitations. First, prevalence surveys that rely on patient-reported use of herbal medicines may be subject to recall bias. This may be deliberate, in that cancer patients may not disclose herbal medicine use, particularly if they have not told the health-care professionals treating them about any herbal medicines or supplements that they may be using (Evans et al, 2007Saxe et al, 2008). Recall bias may also be inadvertent, where patients may not remember whether or not they have taken herbal medicines since their cancer diagnosis, and consequently either under- or over-report their herbal medicine use. With respect to the issue of non-disclosure, patients were informed that all survey responses would be kept confidential and that members of their medical team would not see any of the information that they supplied in response to the survey.

Second, responder bias may mean that we have either under- or over-estimated the prevalence of herbal medicine use by cancer patients in our study population. Responders to the survey were more likely to be affluent, older, and in the White ethnic group, although the proportion of survey respondents in the White and non-White ethnic groups was broadly representative of the ethnic mix of oncology patients in England (National Cancer Intelligence Network, 2009). However, by age and gender standardising our prevalence estimate to the England cancer patient population, we have derived a reliable estimate of herbal medicine use by cancer survivors.

To minimise the risk of distress, patients known to be terminally ill or whom the responsible consultant believed could have been distressed by receipt of the survey were excluded from the mailing. It is possible that this group may have been more likely to use herbal medicines to help them cope with the stress they were experiencing, and thus we have under-estimated the overall prevalence of herbal medicine use by cancer patients. However, we have no evidence to support or refute this possibility.

Finally, our survey was conducted with individuals being followed up at a single hospital, which may affect the wider generalisability of the findings. However, alongside the benefits of age and gender standardisation, the inclusion of comparison data derived from repeating the survey on a smaller scale at a hospital in Birmingham, involving a patient population with very different sociodemographic characteristics adds validity to our findings. This is particularly so given that there was no statistically significant difference found between the prevalence rate from the larger survey and the rate observed within the comparison population (19.7%; 95% CI: 17.4–22.1 vs 16.6%; 95% CI: 11.9–22.2; P=0.292) despite the comparison population including a greater proportion of older patients, more males, more patients from non-White ethnic groups, and a higher number of socioeconomically deprived patients than the population in UHC&W.

Conclusions

It is likely that a substantial number of people with cancer are taking herbal medicines at any one time. With such a high number of potential users and the potential for adverse effects, including adverse drug interactions, a robust evidence base for understanding all aspects of herbal medicine use by those with cancer is required. An understanding of the self-medication behaviours of these individuals is essential if health-care professionals are to support treatment adherence and avoid unwanted pharmacological interactions and compromised treatment efficacy. Health professionals need to be aware of which herbal medicines are being taken by their patients. The provision of relevant educational resources for both patients and health professionals is required.

Change history

  • 29 March 2012

    This paper was modified 12 months after initial publication to switch to Creative Commons licence terms, as noted at publication

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Acknowledgements

We would like to acknowledge the support of staff from the Arden Cancer Research Centre (University Hospitals Coventry and Warwickshire NHS Trust), and University Hospitals Birmingham NHS Foundation Trust in identifying our survey populations. We would also like to acknowledge the input to the design of the study provided by Dr Neil Steven, University of Birmingham. The study was funded by Macmillan Cancer Support, 89 Albert Embankment, London, SE1 7UQ. Ethical approval for this study was obtained from the Birmingham East, North and Solihull Research Ethics Committee (REC), ref 08/H1206/153. R&D approvals were obtained from University Hospitals Coventry and Warwickshire NHS Trust (ref RG053908), and University Hospitals Birmingham NHS Foundation Trust (ref RRK 3625).

Author information

Authors and Affiliations

  1. Primary Care Clinical Sciences, School of Health and Population Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

    S Damery, C Gratus, S Warmington, J Jones, S Greenfield, G Dowswell & S Wilson

  2. Arden Cancer Research Centre, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, CV2 2DX, UK

    R Grieve & J Sherriff

  3. Section of Pharmacology, Therapeutics and Toxicology, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK

    P Routledge

Corresponding author

Correspondence to S Damery.

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