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.