Cancer-related correlates of Traditional and Complementary Medicine use among Norwegian cancer survivors: A cross-sectional study

Abstract

Background

Cancer survivors are a diverse group with varying needs that are patient-, disease-, and/or treatment-specific. Cancer survivors have reported supplementing conventional anti-cancer treatment with Traditional and Complementary Medicine (T&CM) to combat the effects of the disease, as well as the adverse effects of conventional anti-cancer treatments, at different phases of their diagnosis. We aimed to study disease- and treatment-related correlates of T&CM use among Norwegian cancer survivors.

Methods

Data was collected from the seventh survey of the Tromsø Study, Tromsø 7, conducted in 2015-16 among residents of the Tromsø municipality aged 40 and above. Of the 32 591 inhabitants invited, 21 083 accepted the invitation leading to a response rate of 64.7%. The Tromsø study consists of a three-part questionnaire and a thorough clinical examination. In addition to data from the Tromsø study, data on cancer diagnosis and conventional anti-cancer treatment were collected from the Cancer Registry of Norway. Pearson chi-square test, Fisher’s exact tests and independent sample t-test were used to compare T&CM users with non-users. Statistical significance was set at the p-value of < 0.05. All statistical analyses were conducted using Statistical Package for Social Sciences (SPSS) version 28.0 for Windows.

Results

T&CM was used by 31.2% of the participants with natural remedies as the most reported modality of T&CM (18.2%, n = 238), followed by self-help practices of meditation, yoga, qigong, or tai chi, which was reported by 8.7% (n = 114). Provider-based T&CM were reported by 10.0%, where each (acupuncturists; traditional healers; and other CM providers) were reported by 4% of the participants, respectively. Users of T&CM were significantly younger and more likely to be female (p < .001) than the non-users, with higher use of T&CM among females with poor self-reported health, distant metastasis, and being 1–5 years post-diagnosis. Lower use was found among women who received a combination of surgery and hormonal therapy. Similar trends were seen in males, but not at a significant level. For both males and female, T&CM was most frequently used by those with only one cancer diagnosis (p = .046).

Conclusion

The findings suggest that there is a difference in clinical predictors for T&CM between female and male cancer survivors, with more clinical predictors among females.

Background

In Norway, about 35 000 new cancer cases are recorded annually, with an overall growing number of cancer survivors. More males (54%) are diagnosed than females (46%), and the country’s median age at diagnosis is 70 years for both sexes[1]. Cancer survivorship is broadly defined as a continuum from the time of diagnosis to the end of one’s life [2]. Although this implies a commonality, cancer survivors are a diverse group with varying needs due to factors such as cancer type [3], stage at diagnosis [4], age at first diagnosis [5, 6], racial differences [7, 8] and disparities [9], and anti-cancer treatment [10, 11]. Besides breast cancer being the most common cancer in females and prostate cancer being the second most common in males worldwide [12], sex also plays a role in cancer incidence and mortality beyond reproductive organs among survivors [13]. Due to the various differences, cancer survivors face adverse outcomes to varying degrees such as pain, fatigue, and gastrointestinal symptoms as a direct result of the disease [14]. Additionally, the most common conventional cancer treatment forms such as surgery, chemotherapy, radiation therapy, and hormonal therapy can have adverse effects [15–17]. The risk can increase when these modalities are used in combination [18].

Some effects, known as late effects of treatment, appear months to years after treatment [19]. These effects range from pain, fatigue, cardiotoxicity, lymphedema, neurological complications to secondary cancers [20, 21]. In addition to these physical effects, cancer survivors face psychological distress such as fear of recurrence which can result in anxiety, fear of death, and cognitive challenges [22]. To combat these effects, many cancer survivors report using Traditional and Complementary Medicine (T&CM) modalities [23–25].

T&CM can generally be defined as health practices not part of conventional medicine [12, 26]. Additionally, traditional medicine draws from the knowledge, beliefs, and century old experiences of indigenous peoples [27]. Other reasons given for the use of these modalities are to increase the body’s innate ability to fight the disease and to improve physical and mental well-being [28, 29]. Other reasons given are to improve prognosis and increase the chance of recovery [30]. All of which reflect the complex effects of cancer that survivors deal with, and possible insufficiencies in cancer survivorship care. Especially if symptoms experienced are not recorded by health care providers, as shown before [31].

The prevalence and type of T&CM used vary regionally for cultural [32] and economic reasons [33, 34]. For example, it is reported that it is used by up to 80% of the cancer survivors in some African countries where costs of conventional anti-cancer treatment are too high for many inhabitants [35], and over 90% in some Chinese regions where traditional Chinese medicine is prevalent [36].

Use of T&CM before a cancer diagnosis has been shown to remain mainly unchanged upon diagnosis [29]. It can then decrease during treatment and return to pretreatment levels after anti-cancer treatment [37]. On the contrary, a remarkable increase in use upon diagnosis has also been shown [38]. Use among long-term survivors is also reported [39]. Socio-demographic factors associated with T&CM use among European cancer survivors are female sex, higher education, and higher income [28, 30]. This is largely true for Norway too [40]. Breast cancer has been found to be a clinical predictor of T&CM use [41]. Longer time since diagnosis [42, 43], advanced stage of disease [44], and metastasis [45] have also been associated with T&CM use. It was also shown that cancer survivors using T&CM were more likely to have a history of surgery and chemotherapy [46]. However, some studies have shown no correlation between clinical factors and T&CM use [37, 47].

Clinical predictors of T&CM use among Norwegian cancer survivors have been studied across decades. A 1995 Norwegian multicenter study found no correlation between T&CM use and stage of disease and time since diagnosis [48]. A multicenter follow-up study from 2002 showed that palliative treatment, metastatic disease, and time since diagnosis predicted T&CM use [49]. In 2009, a study found that survivors with a poor prognosis were associated with more T&CM use than those with a better prognosis [50]. A 2012 study based on data from the sixth Tromsø Cohort Study found no significant associations between T&CM use and time since diagnosis; however, they found breast cancer to be a predictor of T&CM use [40]. As cancer screening programs get better, anti-cancer treatments improve, and the survivorship period lengthens [51], this study aims to revisit cancer- and treatment-related clinical predictors of T&CM use among Norwegian survivors who participated in the Tromsø 7 study.

Methods

Results

Basic characteristics

The study population consisted of 1307 cancer survivors, 655 females (50.1%) and 652 males (49.9%). The average age of the participants was 65.6 years. A total of 74.4% of the participants reported living with a spouse. Most of the participants reported attaining tertiary education (46.8%) and reported medium and high income, (81.7%, Table 1).

Table 1: Prevalence and correlates of T&CM use

Disease characteristics

The most common cancers were prostate cancer (21.9%) and breast cancer (20.0%), followed by melanoma and other skin cancers (9.7%), cancers of the female genital organs (8.0%), colon cancer (7.6%), and other digestive organ cancers (5.5%), lymphoid, hematopoietic, and related tissue cancers (7.1%), other male genital organs (3.7%), and lung and intrathoracic organ cancers (2.4%, Table 1). Other cancers made up 14.0% of the diagnoses. Some non-reproductive cancers were more common in males than in females; other digestive organs than colon 62.2% vs 37.8% respectively, (p = .011).

Nearly two-thirds of the participant (57.7%) did not have metastatic cancer, 23.2% had local/regional spread, while 2.4% had distant metastatic cancer. Only 0.2% had an unknown primary tumor. The average age at first diagnosis was 54.5 years, and the mean time since the first cancer diagnosis was 9.2 years. Most participants had one cancer diagnosis only, n = 1067 (81.6%), and 240 people had 2 or more consecutive cancer diagnoses (18.4%, Table 1).

Use of T&CM

Overall use of T&CM was reported by 31.2% (Table 1). Natural remedies were the most reported modality of T&CM and were reported by 18.2% (n = 238) of the participants, followed by self-help practices which was reported by 8.7% (n = 114). Provider-based T&CM modalities were used by 10.0% (n = 131) and were each (acupuncturists; traditional healers; and other complementary medicine providers) reported by 4.0% of the participants (Table 2). Female cancer survivors reported significantly more use of T&CM than male cancer survivors, 36.9% vs 25.5% (p < .001), and they were more likely to visit a T&CM provider, but not at a significant level (p = .057). However, they reported more use of self-help practices than males (p < .001).

Table 2: Types of T&CM and gender-specific prevalence of use

Relationship between the use of T&CM and socio-demographic factors

Users of T&CM were significantly younger than non-users, 64.0 and 66.4 years respectively (p = .011, Table 1), but only among females at a significant level when sex-specific analyses were made (p = .040, Table 3). The use of T&CM increased with the level of education among females, (p = .005), but not among males (p = .370, Table 2). There were no statistical differences in annual income (p = .0824) and living with a spouse (p = .860).

Relationship between the use of T&CM and cancer-specific factors

T&CM was used by 37.4% of participants with breast cancer, 33.1%, in participants with melanoma, 31.9% of participants with other digestive organs other than the colon, and 30.5% among those with cancer of the female genital organs. A quarter with prostate cancer (25.9%) reported use of T&CM. There were no significant differences in overall T&CM use related to cancer sites in the sample (p = .309), but participants with only one cancer diagnosis were more likely to use T&CM than those with multiple cancer diagnoses (p = .046). We found no associations between self-reported health (p = .077), metastatic disease at first diagnosis (p = .179), time since first diagnosis (p = .072), age at first diagnosis (p = .132), having received only one type of conventional cancer treatment (p = .340) or those who received a combination of conventional treatment (see Table 2 for the various combinations).

Table 3

Gender specific correlates of T&CM use

Natural remedies were the most used T&CM modality across all cancer sites as shown in Table 4. Traditional medicine was used more than the other provider-based modalities by colon cancer patients, hematologic cancer patients, and prostate cancer patients, while acupuncture was the most visited T&CM provider among participants with melanoma and skin cancer, digestive organs other than colon, female genital organs, and lung and other respiratory organs.

Table 4: Percentage of use of different T&CM modalities by cancer site

Poor health, distant metastasis, and time since the first diagnosis were significantly associated with T&CM use in females (Table 3). Females 1–5 years post the first diagnosis reported the most use and those more than 10 years post first diagnosis reported the least use of T&CM (p = .002). Female participants who received a combination of surgery and radiotherapy were associated with lower use of T&CM than participants receiving other treatment combinations (p = .025). Apart from self-reported health, we found similar trends in clinical predictors among males and T&CM use. However, there were no socio-demographic or cancer-related characteristics significantly associated with T&CM use among male participants (Table 3).

Discussion

This study revealed that 31.2% of the participants reported having used T&CM in the preceding year with higher use among female participants 1–5 years post-diagnosis, with distant metastasis, and with poor self-reported health.

Comparable studies

Incidence of cancer types differs globally, as does cancer mortality [62]. Additionally, availability and access to conventional cancer treatments also vary [63]. T&CM modalities are primarily used as a supplement to conventional treatment in the West, but are used as primary treatment in some areas around the globe [63]. Thus, meaningful international cross-study comparison of clinical correlates of T&CM is hard to achieve. For valid comparability, we compare our study to studies carried out in regions with a similar health service landscape, as well as similar access to it. Universal health care exists in all Europe, with the Nordic model (publicly financed comprehensive health care systems) being used in Norway [64].

The sex differences found in this study could be due to sex differences in the psychological and physical effects of the disease and differences in treatment strategies for various reasons like gender bias (where no apparent medical reason justifies why female patients are not offered the same treatment as males [65]). For example, a recent study showed that female rectal cancer survivors were less likely to receive preoperative radiotherapy than male survivors of the same age, level of comorbidity, and tumor depth [66]. Furthermore, female survivors have been associated with greater cancer-related distress [67]. These factors could lead female survivors to seek T&CM to a higher degree than males to compensate for the differences in the treatment offers not given.

Distant metastatic disease was a predictor of T&CM use among female survivors in our study, in accordance with a German study among cancer survivors with melanoma [71], and an earlier Norwegian study that found correlations between T&CM use and metastatic disease regardless of sex [68]. These findings could suggest that survivors at an advanced stage are more willing to supplement conventional treatment and are certainly in accordance with clinical experience where patients with more aggressive disease are more open to every treatment option available to them. Survivors have indeed reported that a diagnosis of distant cancer prompted them to seek out T&CM [69]. Kristoffersen et. al found that cancer survivors who use T&CM were more likely to have metastasis than non-users, and the use was linked to the little hope of cure given by physicians among this group, as well as greater fear of dying due to their diagnosis [50]. Although distant metastases sites can have different clinical outcomes [70], poor prognoses and severe symptoms seen in some survivors has been associated with the use of T&CM [71]. Metastatic cancer can also have led to more invasive cancer treatment and left the participants with a higher burden of late and long-term effects needing attention [25].

It comes as no surprise that poor self-reported health was associated with T&CM use as the perception of health and illness are major motivations for health care utilization [72]. Poor self-reported health has been associated with use of T&CM [73, 74] and with higher utilization of health services in general [75]. This finding can also be seen akin to metastasis, in that perceived poor health opens survivors up to supplementing conventional treatment for improvement of their health. Indeed, a recent Norwegian study found that most cancer survivors using T&CM used it to increase quality of life and well-being [76].

The use of T&CM was also associated with time since diagnosis among females in our study. Female participants 1–5 years post the first cancer diagnosis (short-term survivors) were more likely to use T&CM than those less than a year (acute survivors), and more than 5 years post-diagnosis (long-term survivors). This is in accordance with a study from the U.S. that found more use of T&CM self-help practices among short-term survivors compared to acute and long-term survivors [68]. Our findings of higher T&CM use among short-term survivors are, on the other hand, both similar and discordant to earlier Norwegian studies. Risberg et al. found no correlation between time since diagnosis and T&CM use in a 1995 study [48], but found a correlation between T&CM use and survivorship above 12 months in 2002 [68]. The reason for the higher use among short-term survivors in the current study might be multifaceted. One reason might be the fact that the majority of cancer survivors report unmet physical, emotional and practical concerns post anti-cancer treatment [77], opening them up to the use of non-conventional health services. Additionally, they report a sense of abandonment after discharge [78], a loss of a safety net, and decline in interpersonal support in this phase [79]. These factors might have driven the short-term cancer survivors to use T&CM to a larger degree than acute survivors who are followed by a multidisciplinary team at varying frequencies [80] and long-term survivors who could have adapted better to their diagnoses with time [81]. Although the Norwegian cancer patient pathway entails follow-up such as rehabilitation [82] that would help attend to survivors’ concerns in this phase, a study showed that the post-treatment/rehabilitation period is assigned low priority by professionals due to acute or urgent tasks like palliative care [83]. Additionally, cancer survivorship care is not yet formalized and part of conventional health professional schools’ curricula [84]. Breast cancer survivorship care in Norway, for example, is organized by the hospital that treated the survivor for the first two years with a recommended doctor’s consultation. The third and fourth year follow-up entails telephone consultations or nurse consultations at the hospital that treated the survivor, as well as a clinical examination with a primary or tertiary physician [85]. This can be perceived as inadequate healthcare by some, more so by survivors who use T&CM as they have been associated with high-use behavior of conventional health care services [86]. This mismatch of growing concerns and a less active role of conventional health care providers might make T&CM especially attractive during this transition to life after active anti-cancer treatment. Beyond unaddressed concerns from health care providers, the short-term survivorship period poses new challenges for the survivor. Although anti-cancer treatment might be completed and successful, survivors enter an unfamiliar phase with fear of recurrence, anxiety, and treatment-related or new symptoms [79]. T&CM has therefore been used in this phase to promote health and well-being, prolong life after active treatment, and for disease prevention [78, 87].

Our findings are otherwise discordant with several previous findings regarding the relationship between cancer site and T&CM use. Throughout recent decades breast cancer has been shown to predict T&CM use [28, 30, 40, 46, 88, 89]. The lack of positive correlation between breast cancer and T&CM use among women in the current study might be due to the rather long time since the cancer diagnosis (a mean of 9.2 years) combined with a 12-month prevalence of T&CM. We cannot rule out the possibility that long-term breast cancer survivors used more T&CM than participants with other cancer sites at the time of their acute or short-term survivorship.

In this study, we found negative as well as no associations between the use of T&CM and conventional anti-cancer treatment, contrary to previous studies [46, 88]. Vapiwala et al. found that T&CM use was more likely in survivors with a history of surgery and in those with current or prior chemotherapy in acute survivors during conventional anti-cancer treatment [46], while Berretta et al. found that survivors receiving chemotherapy were more likely to use T&CM in an Italian multicenter survey [88]. The reason for this difference in findings could be twofold. The informants of the Italian survey were undergoing conventional anti-cancer treatment at the time of the survey or had received it no more than three years prior to the survey. The participants in our study were mostly long-term survivors, and therefore, the majority were unlikely to be undergoing anti-cancer treatment at the time of participation in the Tromsø 7 study. Additionally, we investigated T&CM use in the preceding 12 months, mostly long after the anti-cancer treatment took place. Berretta et al. also reported a T&CM prevalence of 48.9%, much higher than that found in our study which might have led to different associations for use.

Strengths and limitations

One of the major strengths of this study is the large study population and rather high response rate and that self-reported cancer was confirmed by a diagnosis recorded at the CRN. This eliminated recall bias in terms of the time of diagnosis, type of cancer, and treatments used. The cohort was also well-balanced with 1:1 ratio of female and male participants. As the questionnaire was linked to a wider population-based health survey, there was minimal risk of self-selection bias to disproportionately attract T&CM users to participate. The sample in the present study also reflected cancer site incidence in Norway at the time of the study [51].

The CRN has an extensive overview of patients’ therapies, but due to low completeness of administered cancer therapies [90], data on several of the treatment modalities was lacking. Thus, interpretation of treatment-related correlates of T&CM use should be with caution.

Even though the questionnaire captures the different forms of T&CM modalities like provider-based, natural remedies, and self-help practices, the questions go ahead to specify the different types, but the lists were not exhaustive. This might have led to a confusion on how to understand T&CM and led to underreported use of T&CM modalities not listed.

It is unlikely that terminally ill cancer survivors participated in this study as the study took place outside a hospital/treatment center setting, and few patients reported very poor health. Additionally, some data on metastasis was missing. Thus, the association between disease severity and the use of T&CM, or lack thereof, could be non-representative in this study.

Although the cross-sectional design highlights correlates of T&CM use, it limits inferences of causality of T&CM use among the participants. Indeed, knowledge on reasons for T&CM use would improve the interpretation of the clinical correlates of T&CM use among cancer survivors. The reader should note that few of the participants of this study were acute cancer survivors, so generalizability of these findings is affected as they apply more to short and long-term cancer survivors. Finally, even though the self-reported use of T&CM regarded use in the preceding 12 months, recall bias could still influence the participants’ answers. We reckon there would be a realistic reporting of provider-based T&CM as these modalities entail meeting the provider and could be easier to recall, but a possible underreporting of non-provider based/self-management T&CM.

Implications of the study

Our findings add to the existing literature on the use of T&CM among Norwegian cancer survivors and have clinical and research implications. We show that clinical characteristics of a cancer diagnosis may help predict T&CM use in female cancer survivors. Conventional health care providers should be more sensitive to these indicators in interactions with survivors and initiate bias-free conversations about T&CM use. Moreso as cancer survivors appreciate open communication about T&CM with their conventional health care providers [91]. This can also help ward off the use of modalities without proven safety. Further research could examine why there is an increase in T&CM use 1–5 years post-diagnosis and solutions should be applied accordingly. This would help address unmet concerns among survivors and improve cancer survivorship care. The use of T&CM and its clinical correlates identified in this study could also help guide policymakers in the further development of survivorship care programs, as well as medical education programs for professionals.

Conclusion

Our study showed that slightly more than a third of the cancer survivors reported T&CM use and that distant metastasis, 1–5 years since first diagnosis, as well as poor self-reported health were correlates of T&CM use in the female participants. These results should be interpreted in the context of Norway which has a heavily subsidized healthcare system and T&CM is paid for out-of-pocket.

Abbreviations

Declarations

Ethics approval and consent to participate

The study has been approved by the Regional Committee for Medical and Health Research Ethics (REK 2014/940) and was conducted in accordance with the Declaration of Helsinki Ethical Principles involving human subjects. Written informed consent was obtained from all participants. This sub project was approved by the Norwegian Centre for Research Data, NSD, under the reference number 750871.

Consent for publication

Not applicable.

Availability of data and materials

The raw dataset is not available due to Norwegian privacy regulations. Applicants for any data must be prepared to conform to Norwegian privacy regulations. Access to data files can be applied for upon reasonable request at [email protected]. For more information visit 

https://uit.no/research/tromsostudy/project?pid=709148.

Competing interests

The last author Agnete Egilsdatter Kristoffersen is a member of the editorial board (Associate Editors) of BMC Complementary Medicine and Therapies. None of the other authors have competing interests.

Funding

The publication charges for this article have been funded by a grant from the publication fund of UiT The Arctic University of Norway. No further funding was received.

Authors’ contributions

KN and AEK conceived the study, conducted the initial and final analyses, and drafted the initial version of the paper. TS contributed with intellectual content, gave input in how to interpret and structure the findings, reviewed subsequent versions. All authors have read and approved the final manuscript.

Acknowledgements

We thank the people of Tromsø and the Tromsø Study for giving data to this study. We also thank Akilah Stewart for her recommendations of literature in press and contextualizing existing findings.

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Tables

Table 1: Prevalence and correlates of T&CM use 

* Lymphoid, hematopoietic, and related tissue; ^!n is not equal to 1307 due to missing data; CT: Chemotherapy; RT: Radiotherapy; HT: Hormone therapy 

Table 2: Types of T&CM and gender specific prevalence of use 

*Provider-based: Total users of Acupuncturist, other Complementary Medicine Provider, and or Traditional Healer;**Self-practices = Meditation, Yoga, Qi Jong or Tai Chi. T&CM: Traditional and Complementary Medicine

Table 3: Gender specific correlates of T&CM use among cancer survivors

T&CM: Traditional and Complementary Medicine. *Hematologic=Lymphoid, hematopoietic, and related tissue.  ¹Fisher-Freeman-Halton Exact Test. CT: Chemotherapy; RT: Radiotherapy; HT: Hormonal therapy

Table 4: Percentage of use of different T&CM modalities by cancer site

*Self-practices = Meditation, Yoga, Qi Jong, or Tai Chi; **Hematologic=Lymphoid, hematopoietic, and related tissue; T&CM: Traditional and Complementary Medicine