Our study found that nearly all 116 respondents supported the integration of complementary and integrative medicine (CIM) into cancer care, and believed these therapies can be beneficial to patients with cancer, but the majority of respondents did not feel they had adequate knowledge to advise patients on CIM. For medicinal cannabis (MC), attitudes were more ambiguous, with only half of respondents agreeing that there was adequate evidence for the efficacy of MC, or that MC was beneficial to people with cancer. Nearly all respondents wanted to learn more about complementary therapies; this is consistent with other studies [25]. Only 33% of healthcare professionals felt prepared to integrate CIM into their work. As hypothesised, HCPs knowledge of individual CIM therapies varied between mind-body, and herbs and supplements.

The majority of respondents agreed CIM has beneficial effects for people with cancer. Nearly all respondents believed CIM was beneficial to people with cancer, and mind-body therapies had beneficial effects on psychological symptoms such as depression and anxiety and stress management. MC may benefit cancer-related symptoms, and this was higher for symptoms such as managing cancer and treatment-related nausea and appetite. Side effects of MC were thought to be primarily driving impairment and drowsiness but there was uncertainty around other impacts.

With only a few exceptions, knowledge and attitudes to CIM and MC in our study were not influenced by age, gender, occupation or length of time at the hospital. Those respondents who had worked at the hospital longer and were older were more likely to report confidence in discussing CIM with patients and reported having sufficient knowledge about mind-body practices and herbs and supplements.

Knowledge gaps were highest for MC, with only 10% reporting they had adequate knowledge to recommend or 17% were familiar with the endocannabinoid system. Only 20% of HCPs were confident advising on the benefits and contraindications of herbs and supplements; confidence was slightly higher for mind-body practices (36%). All HCPs wanted to learn more about the benefits of CIM and MC. Interest was highest for dietary supplements (81%) and herbs (81%), with the majority of oncologists wanting to learn about the benefits and contraindications of dietary supplements and herbs.

Despite limited confidence in benefits and contraindications of herbs and supplements, only 7–14% of the HCPs would advise against the use of herbs and dietary supplements. In a pooled prevalence of studies of people with cancer, 22% used herbal medicine, and this is higher in certain population groups such as women with breast cancer where 41% reported use of herbal medicine [26, 27]. Dietary supplement use is higher, with studies indicating use by almost one in two people with cancer (including those receiving cancer treatment), with a slightly lower but significant (36%) level of consumption in men [28–30]. Despite this prevalence of use in Australian cancer patients, respondents in our study did not feel they were equipped to advise on herbs and supplements, and this area received the highest interest by HCPs in learning more, compared to mind-body therapies.

Advice regarding the safe use of herbal medicine or dietary supplement use during cancer treatment is an important part of comprehensive cancer care. Yet only 16 cancer services in Australia have dedicated healthcare practitioners providing advice on the use of any CIM [31]. In our study, there was strong support for a pharmacy service to advise on the potential interaction and safety of herbs and/or supplements with cancer treatments. The majority of respondents stated this would make them more likely to recommend or allow use. More than half of the pharmacists in our survey reported that they were confident in advising on herbs and supplements. For CIM in general, respondents in our study were most likely to refer patients to the integrative and supportive care specialist within the hospital. Taken together, these findings indicate that the safety and choices of people with cancer and their supportive care can be greatly enhanced by providing a level of CIM and MC specialist knowledge within a comprehensive cancer setting.

Meeting cancer patient expectations, cultural preferences, beliefs and information needs improves patient outcomes [32]. One in two Australians with cancer uses CIM; it aligns with their personal values, beliefs and cultural identity [33]. People use CIM to help cope with the side effects of conventional cancer treatments, improve survival and long-term outcomes and support their mental health, wellbeing, weight management, self-efficacy and quality of life throughout the cancer continuum [7, 34–36]. Additionally, patients receiving treatment at an institution that supports an IO program may have improved survival [33, 36–38]. Our survey, in line with other studies, shows that the education, integration, pathways and translation of evidence into practice are major barriers to preferences being expressed by HCPs and people with cancer[16].

The establishment of designated cancer treatment centres in Australia with links to rural and remote centres may provide the basis for speciality advice on integrative oncology to patients and practitioners. Similar to the program of the National Cancer Institute designated cancer centres in the US have developed or are developing integrative oncology programs to assist, along with guidelines to support providers who participate in these programs [39, 40]. This would require the training of healthcare professionals in integrative oncology; competencies and training options are emerging [41, 42].

Whilst knowledge and attitudes of general practitioners to MC have been assessed [43], no studies conducted in Australia have explored attitudes of oncology HCPs. The findings in our study were similar to other studies conducted in Europe, where oncology healthcare professionals increasingly agree that MC reduces patient suffering and has benefits, particularly in people with advanced cancer [23].

The study was conducted at a hospital that has provided a range of CIM alongside conventional cancer care since it opened in 2013 and more recently prescription of MC. Through this exposure, we anticipated that the HCPs surveyed may have different knowledge and attitudes towards CIM compared to participants in other surveys. In other surveys 58–90% of HCPs reported having inadequate knowledge to answer questions about CIM, compared to 51% of HCPs in our study reporting that they felt confident in discussing CIM with patients[16]. However, this knowledge did not extend to side effects of MC or the endocannabinoid system, and most respondents did not have sufficient knowledge to make recommendations about MC use to people with cancer.