Introduction

Tobacco smoking is a known risk factor for several cancers including lung, pancreatic, bladder, cervical, stomach and gastrointestinal cancers [1,2,3]. Continued smoking following a cancer diagnosis is one of the strongest predictors of survival time and is associated with detrimental outcomes [4]. These outcomes include increased likelihood of recurrence, development of secondary primary cancers, reduced treatment efficacy and death [5,6,7,8]. Despite this, approximately 33% of patients continue to smoke after a cancer diagnosis, or relapse to smoking after attempting to quit [4, 9].

The overall global trend of e-cigarette use has shown an upward trend from 2011 to 2019 with current global lifetime and current prevalence of e-cigarette use at 23% and 11% respectively [10]. In Australia, about 11% of the general population aged 14 and over reported ever use of e-cigarettes in 2019 [11]. Ever use was highest among young adults aged 18 to 24 years old at 26%, with lower use among older people [11]. Pooled and weighted data from Australia’s five major cities (Sydney, Melbourne, Brisbane, Adelaide and Perth) also showed a gradual increase in current use of e-cigarettes between 2020 and 2023 (2 to 8.9%) in population aged 14 years and over [12]. Among people previously diagnosed with cancer, aged 18 to 44 years old, US studies showed that the prevalence of e-cigarette use is estimated at 12% [13]. Furthermore, the US National Health Interview survey (2014–2018) found that 23% of people previously diagnosed with cancer actively used e-cigarettes [14]. A recent systematic review and meta-analysis showed that approximately 15% of people previously diagnosed with cancer between 2005 and 2019 reported lifetime use of e-cigarettes, with a higher prevalence in younger people aged < 45 years (46.7%) compared to older people aged ≥ 65 years (24.8%) [15]. Additionally, one study found that 63% of people previously diagnosed with cancer who currently use conventional cigarettes also used e-cigarettes, suggesting dual use in this population [15]. This rise may reflect lower perceived health risks of vaping as a tobacco smoking cessation approach that gradually replaces conventional cigarettes with e-cigarettes.

Nicotine vaping products (NVPs) are a source of known toxic components such as heavy metals, metalloids, nitrosamines and aldehydes [16,17,18]. In vitro and in vivo studies show associations between respiratory conditions such as asthma, increased inflammatory response, oxidative and DNA damage and the aerosol produced during vaping [19]. Although tobacco smoking has higher risk profile for these domains, the health risks associated with NVPs cannot be ignored. Given the increased risk of developing health conditions such as cardiovascular and pulmonary diseases among people diagnosed with cancer during treatment [20], e-cigarette use may prove problematic given that the composition of these products has the potential to affect the development, course and prognosis of these health issues in people diagnosed with cancer. It is therefore imperative to understand the perceptions, attitudes and beliefs of people diagnosed with cancer towards the use of NVPs. We conducted a scoping literature review using a systematic search strategy to investigate the attitudes, beliefs and perceptions of NVPs among people diagnosed with cancer and their cancer care providers, and summarise key themes addressed in this literature. A secondary aim was to note any data on findings relative to information sources used regarding NVPs and prevalence of NVPs use.

Methods

Search strategy

Search terms were developed by reviewing published works for terms involving cancer, NVPs, attitudes, beliefs, or perceptions of NVP use. Research librarians were consulted to develop and refine the search strategy, which is provided in Table 1. Search terms related to “nicotine vaping products”, “perception”, “cancer” and “cancer patients and support” were selected. We identified relevant publications by searching the Scopus and OVID Medline databases for articles published from 2013 to 2023, with final searches run on 22 September 2023.

Table 1 Search terms by construct
Full size table

Inclusion and exclusion criteria

Articles were required to be available in full text, published in English and address perceptions, attitudes, or beliefs relating to NVP use among people with a current or previous cancer diagnosis or clinicians. No specification of cancer type or age was required. Studies from Australia, the USA, UK, Canada and New Zealand were included, to meet the high-income country focus, with other countries excluded. Primary studies using qualitative and quantitative methodologies were included, provided they reported subjective views (i.e., beliefs, attitudes, or perceptions) about NVP use among people with a current or previous diagnosis of cancer. Reviews, preprints, commentaries, conference abstracts, dissertations and grey literature were not included. Further eligibility criteria and participant information are presented in Tables 2 and 3.

Table 2 Characteristics of included studies
Full size table
Table 3 Characteristics of participants in included studies
Full size table

Study selection

Figure 1 displays the flow chart for selection. The search and selection of articles followed PRISMA-ScR guidelines for scoping reviews [21]. The initial set of articles were deduplicated in Covidence, with the final set of unique papers undergoing title, abstract and full-text screening against inclusion and exclusion criteria in Covidence. All literature was reviewed by JB and cross-checked by JT against inclusion and exclusion criteria, with discrepancies resolved by group discussion (LO, JB, JT).

Fig. 1
figure 1

Diagram of study identification, screening and selection

Full size image

Data extraction

A data extraction tool was created in Covidence to summarise study characteristics, including publication year, country of origin, participant characteristics, study design, aims and main findings for all studies that included a quantitative or qualitative component. Extraction was completed independently by two researchers (JB, LO) and any discrepancies resolved by group discussion (JT, LO, JB). Findings were extracted to a descriptive summary table (Tables 2 and 3).

Data analysis

Findings from all included studies were narratively synthesised, given the range of methodologies and populations addressed in the final set of studies, and to identify key concepts across the studies. Study outcomes were first categorised according to initial themes, and these were discussed among the study team. We then refined and named the final themes, with one author (LO) summarizing included studies in a narrative framework. This framework included the data extraction fields and factors relating to risk perception, smoking cessation, social interaction and NVP use context. This framework was then discussed in relation to the original themes for consensus.

Results

Nine articles met the eligibility criteria for inclusion in this review, following screening of 790 studies, with 605 unique studies screened by title and abstract, and 17 unique studies screened by the full text (Table 2). Studies were excluded at full text due to being out of scope, or by originating country and population. The included studies spanned from 2018 to 2022, with seven studies from the USA and two from the UK. Other high-income countries were not represented in studies eligible for inclusion. Eight quantitative and one mixed methods study with a qualitative component were identified. No solely qualitative studies were eligible for inclusion. Two studies assessed clinician perspectives, while seven studies assessed perceptions of people with a current or previous cancer diagnosis. Beliefs assessed included relative harm in comparison to cigarettes, smoking cessation aid and use during cancer treatments. The aim of this study was to scope the literature; therefore, study quality was not assessed.

Perception of NVPs

Four studies examined perceptions or attitudes towards e-cigarettes among people with a current or previous cancer diagnosis [22, 24, 25, 27]. Of these studies, three reported reduced harm perception and risk belief of e-cigarettes compared to conventional cigarettes [24, 25, 27], and one study reported a greater harm perception of e-cigarettes compared to conventional cigarettes among people diagnosed with cancer [22]. One study showed that current users considered e-cigarettes to be less detrimental to their cancer treatment effectiveness and less likely to increase the risk of cancer treatment-related problems, relative to smoking [25]. One study also noted that participants (with and without a cancer diagnosis) who believed that e-cigarettes were just as or more harmful than conventional cigarettes were less likely to ever use e-cigarettes compared to those who believed that they were relatively less harmful [27]. Among those with a history of cancer, the belief that e-cigarettes were more harmful than conventional cigarettes was associated with lower likelihood of having ever used e-cigarettes (aOR 0.16; 95% CI; 0.04–0.57) [27]. Four studies assessed possible reasons for e-cigarette use among people diagnosed with cancer [24, 25, 28, 29]. Smoking cessation or reduction was the most common reason given for e-cigarette initiation and continued use, followed by ability to use nicotine in non-smoking areas, and use of a perceived lower risk alternative to tobacco. One study reported that 21% of people diagnosed with cancer initiated use due to health concerns related to their cancer diagnosis [25].

Clinician attitudes towards NVPs as smoking cessation tools

Two studies also assessed clinician attitudes and beliefs towards e-cigarettes [30, 31]. One study (n = 147) [30] reported that practitioners were most likely to advise that e-cigarettes were less harmful than regular cigarettes (23.7%). Practitioners also reported a scarcity in research and uncertainty regarding possible health effects associated with e-cigarette use (21.6%). Some practitioners provided no advice to patients or suggested that they had inadequate knowledge to advise patients (6.3%), while 3.7% stated that they would encourage use and 5.8% would discourage use [30]. The second study [31] reported that 29% of clinicians (n = 506) would not recommend e-cigarettes to patients with cancer who smoke tobacco, 51% would recommend e-cigarettes as an interim option to patients, while 20% would recommend e-cigarettes as a partial replacement for smoking [31]. Many clinicians (42%) felt uncomfortable discussing e-cigarettes with their patients, and 38% noted that most of their colleagues would also feel uncomfortable recommending e-cigarettes to patients with a cancer diagnosis. Furthermore, 37% were unsure whether clinicians should discourage patients with a cancer diagnosis from using e-cigarettes [31].

Many clinicians and healthcare professionals reported low levels of confidence or insufficient knowledge regarding e-cigarette related advice, with the vast majority stating that they need more information and guidance regarding e-cigarette advice to patients [30, 31]. Uncertainty regarding the safety of e-cigarettes in comparison to conventional cigarettes or tobacco was also evident in both studies [30, 31]. One study reported inconsistent advice given to patients by practitioners [30]. Almost one in four (24%) of practitioners (n = 141) advised patients that e-cigarettes were less likely to be harmful compared to conventional cigarettes despite insufficient evidence available to inform the adverse effects of e-cigarette use. On the other hand, 6% of clinicians provided no advice [30].

While participants in one study stated that they felt comfortable discussing e-cigarettes with their oncology provider and believed it was important to do so, most participants did not know their provider’s stance because it was never discussed [25]. Less than half (n = 121) told their providers about their e-cigarette use, and only 24% reported being asked about their usage [25]. Participants in a separate study reported speaking to their physician about e-cigarette use and noted that their doctors do not support use due to perceptions of harm or lack of knowledge about harms and safety [29]. Some participants also perceived that their doctor viewed e-cigarettes as more harmful than conventional cigarettes [29].

Information sources

In one study, all people diagnosed with cancer (n = 39) had heard of e-cigarettes and reported initial exposure from various sources [24]. Common sources of e-cigarette information included television (77%), stores (49%), friends (36%), family (31%), internet advertisements (10%), magazines (5%), radio (5%), newspaper (5%) and healthcare providers (5%) [24].

Regarding health practitioners, many clinicians in one study (n = 506) had sought information about e-cigarettes from government or health agencies (55%), professional associations (37%), healthcare colleagues (29%), news media or advertising (24%), in scientific literature (23%), or professional development training (22%) and charities (18%). Notably, 19% of clinicians reported having never sought information about e-cigarettes [31].

Prevalence of NVP use among people with a current or previous cancer diagnosis

All studies identified prevalence of e-cigarette use among people with a current or previous cancer diagnosis [22, 24,25,26,27,28,29,30,31]. Two studies compared nature and frequency of e-cigarette use between people with a previous cancer diagnosis and those without a cancer history [22, 27] with one large study (n = 11,847) reporting current e-cigarette use in 2.9% (95% CI 1.4–4.3) of people with a previous cancer diagnosis and 5% (95% CI 4–6) in respondents without a cancer diagnosis [22]. However, similar overall distinctions in frequency and nature of use were not clearly defined in the second study [27]. Other studies focused solely on people with a current or previous diagnosis of cancer [24,25,26, 28,29,30,31] with up to 49% of participants (n = 302) reporting ever use and 19% reporting current use [28]. In two studies, up to 42% of practitioners and clinicians estimated regular use of e-cigarettes among 25% or more of the ever-smoking patients seen in the past year [30, 31]. One study also reported dual use of tobacco cigarettes and e-cigarettes among 51% of people diagnosed with cancer (n = 121 current users) [25].

Discussion

This scoping review sought to examine attitudes, beliefs and perceptions of people diagnosed with cancer and their health practitioners on NVP use. Findings revealed lower harm perception of e-cigarettes compared to conventional cigarettes among people with a current or previous diagnosis of cancer. Reasons for use included smoking cessation, nicotine use in non-smoking areas and lower perceived health risk relative to conventional cigarettes. Findings also suggested that most clinicians would not recommend e-cigarettes to their patients due to low confidence in the efficacy and safety of e-cigarettes as well as insufficient knowledge. Prevalence of e-cigarette use remains quite high among people with a current or previous cancer diagnosis, with dual use reported in just one study.

Studies show an association between reduced harm perception of e-cigarettes and greater odds of e-cigarette initiation or use among young people [32,33,34,35]. It is likely that the reported reduced harm perception of e-cigarettes may influence prevalence of use of these products among people with a current or previous cancer diagnosis, particularly among people who currently smoke or have smoked in the past. Nevertheless, reasons frequently given for e-cigarette use among patients include smoking cessation and use of a perceived lower risk alternative. Continued smoking during cancer treatment is associated with detrimental outcomes [4], such as cancer recurrence, secondary primary cancers and reduced treatment efficacy [5,6,7,8]. Considering e-cigarettes as less detrimental to treatment effectiveness and less likely to increase risk of treatment complications [25] may increase the likelihood of using e-cigarettes in this context. Although evidence exists to support the use of e-cigarettes as a smoking cessation tool [36, 37], the application of this for people with a cancer diagnosis who aim to quit smoking requires more evidence, particularly for longer-term outcomes. Interestingly, the only longitudinal smoking cessation trial selected for synthesis in this review showed that e-cigarette use during trial participation was not associated with smoking abstinence at 6 months among individuals who smoke and have been recently diagnosed with cancer [29].

Clinicians and healthcare workers also expressed apprehension regarding NVPs. Findings suggested that clinicians remained uncertain about the safety and efficacy of e-cigarettes and viewed these products as just as harmful or more harmful than conventional cigarettes. This sentiment is echoed in different medical fields [13, 38, 39]. However, unlike current findings, we do see an increased likelihood of physicians such as general practitioners recommending e-cigarettes to people who smoke in other patient groups depending on age, smoking status and prior use of nicotine replacement therapy [13, 40] despite sharing similar uncertainties about the efficacy of e-cigarettes. The increased risk of e-cigarette use on health or treatment outcomes of people diagnosed with cancer compared to other patient groups is likely to inform hesitance to suggest NVPs for smoking cessation.

Differences in harm perception and attitudes were identified between patients and clinicians in this review, which may be attributed to information sourcing. While patients obtain information from television, stores, friends and family [24], clinicians tend to rely on health-related sources such as scientific literature, government or health agencies and professional colleagues [31]. Despite accessing scientific literature, clinicians still expressed a lack of confidence in discussing e-cigarette related information with patients. One study observed an association between a greater frequency of discussing patients’ e-cigarette use and greater perceived knowledge of e-cigarettes among health practitioners [41]. The same study also showed that nursing practitioners and physician assistants were more likely to discuss e-cigarette use with patients compared to oncologists [41]. Currently, clinical guidelines on smoking cessation are being adapted to incorporate evidence and practice considerations for patients’ use of NVPs to quit smoking [42]; however, there is a need for further evidence to inform use among people currently or previously diagnosed with cancer to facilitate discussions between health practitioners and patients. The development of accessible and reliable health materials and campaigns is also required to bridge the difference in harm perceptions of NVPs between people diagnosed with cancer and their healthcare providers.

This scoping review is not without limitations. Studies captured in this review were not able to be directly synthesised (e.g. across age groups), due to methodological variation and use of different outcome measures. Studies in this review also mainly evaluated knowledge, attitudes or perception of e-cigarettes but not the impact of perception on initiation or frequency of use in people diagnosed with cancer. This was largely due to the deliberate focus on subjective and attitude outcomes, rather than standardised outcome measures. As all but two studies were from outside the USA, the findings have less relevance to lower income countries, and further research on this is warranted. One other important consideration is the prevalence of NVP use among clinicians. Although this lies beyond the scope of this review, it is an important consideration for future work given its likely influence on NVP recommendation to patients among clinicians. Interestingly, results from this review only yielded articles published between 2018 and 2022 and predominantly from the USA (none identified from Australia, Canada or New Zealand). This further highlights the lack of research in this space and points to the need for sufficient evidence to enable discussion between health practitioners and people diagnosed with cancer.

Conclusion

People with a current or previous cancer diagnosis commonly perceive e-cigarettes to be less harmful and safer than conventional cigarettes, while clinicians and healthcare providers remain uncertain about the safety of these devices, both of which have implications for clinical practice. Communication between clinicians and patients regarding use of these devices remains inconsistent due to differences in harm perception and confidence in use. Future study is needed to identify the relationship between decreased harm perception and initiation and use of e-cigarettes among people diagnosed with cancer. Further evidence is also needed on the efficacy of e-cigarettes as a smoking cessation tool for people diagnosed with cancer, given its popularity within this population. As it stands, e-cigarette use is associated with adverse lung and cardiovascular outcomes; however, little is known regarding its potential risk of on cancer treatment efficacy and outcomes. Development of resources for healthcare professionals is also required to aid in discussions and recommendations regarding e-cigarettes between clinicians, people diagnosed with cancer, survivors and supports.