How often is complementary and alternative medicine (CAM) used by cancer patients, and why do they use it? Cancer is among the most frightening of medical diagnoses, and it is not surprising to expect that cancer patients may wonder if non-standard or unconventional treatments might have any benefit. A new paper by Martin Keene and colleagues from the College of Medicine and Dentistry at James University in Australia sheds some new light on this this subject. But before we get to the study, we need to discuss the first problem the authors encountered – what exactly is CAM, anyway?
CAM in the eye of the beholder
Some consider anything sufficiently “natural” to be CAM. Others point to who sells it – CAM tends to be delivered by non-health-professionals, but some health professionals (and health organizations) offer CAM and conventional medicine side by side. David Gorski and others at this blog have written about the evolution of CAM, which was once called quackery. Rather than disappearing, these products came to be known as alternative medicine over time.
Alternative medicine sounds outside the mainstream (and it was), meaning it’s an alternative to conventional medicine. Alternative medicine proponents didn’t like this, and so the term became “complementary and alternative medicine”, which retained the quackery, but added in utterly conventional treatments like dietary interventions and exercise. Consequently, perfectly reasonable and even science-based interventions suddenly fell into the “CAM” category, alongside rank quackery and interventions that were unproven, disproven, or arguably harmful. So if we don’t even have a common definition to work from, is it possible to objectively assess its use? CAM is mostly defined by what it is not, rather than by what it is.
This image reflects my own thinking about CAM and cancer – a continuum ranging from science-backed interventions, used alongside cancer treatments, that may help quality-of-life and symptoms (e.g., supportive care), to implausible, unproven or disproven treatments, some of which may be claimed to actually treat the underlying cancer:
Why is understanding CAM use in cancer important?
Widespread but undisclosed use of CAM has the potential to compromise cancer care. While few patients forsake science-based cancer care in favour of CAM, concurrent use is more common. Some CAM products can affect bleeding risk or may even compromise the effectiveness of chemotherapy. Notably, non-disclosure of CAM use to health professionals is common, with numbers in the literature suggesting 20%-77% of cancer patients never disclose CAM use.
This study for discussion today was a systematic review – a comprehensive search of the medical literature for all studies, which were then rolled up into a single analysis. Studies included had to be in the English language, developed with the intent of determining CAM use, had data with at least 100 subjects, in patients who were active cancer patients. Importantly, studies were excluded if they exclusively studied so-called “mind and body” interventions, like yoga or prayer. Data was extracted from each study in a standardized way and compiled for analysis.
The paper is entitled “Complementary and alternative medicine use in cancer: A systematic review” and it was published in the journal Complementary Therapies in Clinical Practice.
The authors identified 61 relevant studies that included over 20,000 cancer patients in total. Breast cancer patients were the most common patient group studied, followed by hematologic (blood) cancers. Interestingly, this topic is under-researched in North America. The most common country among the 61 studies was Germany (9), followed by Turkey (6), Australia (5), and Malaysia (5). There were 4 from Italy and the USA, with several other countries represented by 3 or fewer studies. In most of the studies, self-completed questionnaires were the source of data.
Importantly, 53 of the 61 studies had a definition of CAM that included mind/body therapies. Only 5 studies looked solely at “biological therapies” such as herbal remedies or dietary supplements. Overall, the diversity of and generous definition of CAM serve to over-estimate the population of CAM users (if you feel, like I do, that broad definitions co-opt what arguably isn’t alternative medicine).
Prevalence – On average, 51% of cancer patients were using CAM, ranging from 16.5% to 93.4%. The authors attempted to break this down by cancer type, but statistical analysis showed no difference between groups, so I won’t show that data here. In addition, there were no statistically significant differences between different countries in terms of prevalence of use.
Demographics – 56 of the 61 studies looked at the demographics of users. The most common predictors of CAM use were:
- female (even after controlling for the multiple studies in breast cancer)
- higher education
- higher income
- previous CAM use
Reasons for CAM use – The desire to treat or cure cancer was the most commonly cited reason for use, noted in 74% of studies. Other reasons given included intent to treat complications (e.g., side effects) (61%), influence general health (e.g., increase immunity) (57%), holistic treatment (57%), “Taking Control” or “Not wanting to miss a chance” (46%), and belief in CAM or dissatisfaction with conventional treatment (34%).
What does this study tell us?
This paper further confirms what we know about CAM and cancer. Importantly, CAM is a cultural phenomenon, and not a product of science or evidence. As Steven Novella has noted previously, satisfaction with mainstream medicine is not an important factor in deciding to use CAM, and CAM users are generally satisfied with their mainstream care. CAM may be popular because its use aligns with a user’s personal philosophy, or simply to expand their options, perhaps because it is widely viewed as being natural and harmless. A 2013 systematic review in advanced cancer noted that use was felt to offer hope and even ambiguity about the future in these patients with a terminal cancer diagnosis. That study, like this systematic review noted that patients who were younger, female, more educated, had a longer duration of disease, and had previously used CAM were more likely to use CAM. And a 2015 cross-sectional survey of patients at an academic cancer centre found that attitudes towards CAM predict CAM use. Patient age (<65 years), female gender and college education were associated with greater expected benefit from CAM.
Does concurrent use of CAM with conventional cancer care affect survival or quality of life?
It’s possible that CAM, when used concurrently with conventional medicine, might offer some subjective benefits, particularly for side effects. However, given the potential for CAM-drug interactions (in the case of supplements and herbal remedies), survival benefits shouldn’t be assumed. A study of a Korean population by Yun and colleagues suggested that CAM had no effect on survival and worsened, rather than improved, quality-of-life. Similarly, so did a Malaysian study by Chui. Armstrong found no difference in QOL due to CAM in a study of patients with brain tumours. Risberg, studying a Norwegian population, also observed that concurrent CAM use predicted a shorter survival. However, the U.S. Health, Eating, Activity, and Lifestyle Study found no relationship between CAM use and breast cancer (or overall) survival. Overall, based on this limited evidence, it’s reasonable to conclude CAM may offer cancer patients subjective benefits. However, there is no convincing evidence CAM use actually improves quality of life or has any beneficial effect on survival.
Conclusion: Little evidence to support CAM benefiting cancer patients
If CAM works, it does so according to scientific principles – not alternative ones. There is no evidence that most of CAM has much to offer cancer patients, even when used alongside conventional care. Importantly, no treatments, even some forms of CAM, are without any risk. However, cancer patients may be more willing to accept the risks of CAM given their diagnosis. This systematic review confirms that many to most people with cancer are using some form of CAM. Given the variety of approaches and therapies that now encompass CAM, cancer patients should be made to feel comfortable discussing CAM with their health care providers. Health professionals need to take a non-judgmental approach to understanding CAM use, while providing advice based on the best scientific information, with the goal of to supporting patient autonomy and safe, optimal cancer care.