Helping cancer patients quit smoking by increasing their risk perception: a study protocol of a cluster randomized controlled trial

The present study aims to test the effectiveness of a specially designed smoking cessation intervention using a risk communication approach for cancer patients who are smokers, to (i) achieve a higher quit rate, (ii) improve their smoking behaviour, (iii) motivate their intention to quit smoking, (iv) improve their risk perceptions of continued smoking, and (v) improve the quality of life.

The theoretical framework is shown in Fig. 1. The framework is constructed with reference to the nicotine addiction context in smoking [18], and a modified Theory of Planned Behaviour (TPB) to guide the development of the smoking cessation intervention [19]. We assume smokers who have cancers will quit smoking if they have positive attitudes, subjective norms and perceived control on quitting, while the antecedents are mediated by intention. In addition, we will use a risk communication approach in the Self-Regulation Model of Illness [20] to influence patients’ attitudes toward quitting (behavioural beliefs) and their normative beliefs. We will apply part of the Transtheoretical Model (TTM) to guide the risk communication (in form of the pros and cons of behavioural change) and increase the self-efficacy of participants [21]. The concept of risk perceptions have been found to be a cue to promote healthy behaviour among patients.

Cancer patients fulfilling the following inclusion and exclusion criteria will be invited to participate in the study. The inclusion criteria are: (1) smoked weekly in the past 6 months, (2) diagnosed with cancer that are related to smoking [2], such as cancer of the oropharynx, larynx, lung, oesophagus, trachea, bronchus, acute myeloid leukaemia, stomach, liver, pancreas, kidney, ureter, and bladder, and colorectal, (3) diagnosed with cancer for at least 6 months (such that their conditions and treatments would be stable), (4) patients in all stages I, II, III, or IV, (5) aged 18 or above, and (6) can communicate in Cantonese. The exclusion criteria are: (1) those with unstable medical conditions as advised by the doctor in charge, (2) poor cognitive state, (3) having mental illness, and (4) those participating in other smoking cessation program. The oncologists and oncology nurses will assess and inform us the stability and suitability of the cancer patient to participate. The patients would be at different phases/ stages but they will also be eligible, if confirmed by the oncologists/ oncology nurses.

Approval for the study has been obtained from five hospital ethics committees (Kowloon West Cluster Research Committee; Hong Kong East Cluster Ethics Committee; Kowloon Central/Kowloon East Research Ethics Committee; Hong Kong West Cluster Ethics Committee; and New Territories West Cluster Clinical & Research Ethics Committee). To ensure the rights of all participants will be protected, the research carried out will be in compliance with the Helsinki Declaration (http://​www.​wma.​net/​en/​30publications/​10policies/​b3/​index.​html). Research assistants will approach patients in the oncology out-patient clinic and ask them whether they are smokers or not. The eligible subjects will then invite to participate in this study after they are told the purpose of the study. They will be given the option of participating or refusing involvement in the study and will be told that their participation is voluntary without prejudice. Written consent will then obtain from all participants.

To evaluate the effectiveness of a smoking cessation intervention using risk communication approach, a total of 560 eligible Chinese cancer patients were recruited from five out-patient clinics in Hong Kong. After completing the baseline questionnaire, subjects will receive proposed intervention according to their group assignment. Four consecutive (3-, 6-, 9- and 12-month) follow ups will be conducted by trained interviewers (blinded to the group assignment) with all subjects via telephone. We will assess hospital readmission and other clinical outcomes from the participants’ medical records accordingly. Patients who have successfully quit smoking at 6-month will be invited to come back to the out-patient clinic and have biochemical validation tests (saliva cotinine test and exhaled CO test). We will offer HKD300 (USD38.5) per client to cover their travel expenses and time cost. From our previous experience, such an incentive is necessary to secure a sufficiently high response rate.

Randomization will be done with each session in an out-patient clinic as a cluster unit. Currently there are 10 sessions per week per study site. Before the study, we will randomly draw the sessions by computer generated random sequence (block randomization with each hospital as a block unit), so that 5 sessions will be treated as intervention group and another 5 sessions will be treated as control group per week. Participants who consent to participate in the study will be assigned to either intervention or control group depending on the out-patient clinic session that they are seeking consultation. By using this experimental design, we can ensure similar proportion of smoking cancer patients will fall into the intervention and control group in each out-patient clinic, and each out-patient clinic will have a similar proportion of cancer patients into the intervention/ control group. We expect the intervention and control group would have similar socio-demographic profile, smoking history, and clinical history and we shall check for any differences, and if any, we shall adjust for them in the analyses. In using the cluster randomization design with a session being a cluster unit, the patients who are randomized into the experimental and control groups would have less chance to meet each other in the out-patient clinic and discuss the contents of the smoking cessation interventions.

Ten patients from the experimental group will be invited to participate in an in-depth interview after they have completed the 6-month follow up survey to examine their experience in quitting and the effect of the interventions from their perspective. Questions such as their satisfaction, perceptions on the advantages and disadvantages of the intervention, and any other suggestions for improvement will be explored and discussed

The primary outcome is the self-reported 7-day point prevalence (PP) quit rate of the smoking cancer patients during 6-month follow up. The secondary outcomes include (a) self-reported 7-day PP quit rate at 12-month follow-up and the biochemically validated quit rate at 6-month follow-up (non-smoking status is confirmed by a carbon monoxide level in expired air < 9 ppm and saliva cotinine level < 115 ng/mL in parallel test), (b) percentage of patients reduced smoking by at least 50 % at 6- and 12-month follow-up compared to baseline, (c) percentage of patients with quit attempt(s) at 6- and 12-month follow-up, (d) change in the intention to quit smoking (stage of readiness to quit) at 6- and 12-month follow-up compared to baseline, (e) change in risk perceptions of continued smoking at 6- and 12-month follow-up compared to baseline, and (f) change in health-related quality of life at 6- and 12-month compared to baseline.

Sample size is calculated by “Power Analysis and Sample Size (PASS) v. 13” (http://​www.​ncss.​com/​pass.​html) and based on the main outcome variable according to the main hypothesis, the 7-day point prevalence self-reported quit rate at 6-month in the experimental group is higher than the control group. A previous RCT study [28] conducted in Australia, which applied motivational intervention to 137 smoking patients with mixed cancer sites. Based on that study, the self-reported 7-day point prevalence quit rate at 6-month follow up was 29 % for the intervention group and 18 % for the control group. To detect a statistical difference at 5 % significant level and a power of 0.8, 233 patients will be needed in each of the 2 groups (based on independent samples Fisher exact test). With reference to the local RCT on smoking cessation intervention for cardiac patients [22], we assume a 15 % attrition rate at the 6-month, and 274 patients will be required in each group to achieve a significant outcome. Accounting for the clustered randomized sampling design with 20 clusters (sessions) and an intra-class correlation of 0.002, 280 patients will be required per group, adding up the total sample size to 560 from the experimental and control groups together.

From the information provided by our clinical partners on site screening, there are around 2000 new patients per hospital per year. According to our previous qualitative study [23] conducted in an out-patient clinic on Chinese current smokers and ex-smokers, about 13.7 % patients continued smoking after receiving a cancer diagnosis (274: 13.7 % of 2,000). However, more than 50 % of these smokers were reluctant to quit (137: 50 % of 274). In a rough estimation, there will be around 700 eligible subjects in five acute Hospital Authority hospitals each year. We have confidence that we can recruit adequate subjects (560) according to the power analysis within an 18-month (78-week) recruitment period.

For the process evaluation, all qualitative data from interviews will be tape-recorded and transcribed verbatim. Content analysis will be employed and themes identified. The constant comparative method will be used to search for common constructs and themes about the implementation and the effect of the intervention as perceived by the participating subjects.

This study will make an important contribution to evidence-based practice by testing the effectiveness of a tailored smoking cessation intervention targeting cancer patients.

If it is proven to be effective, the findings of this research have great potential to influence practice not just in out-patient clinics but also in wider health service and other public sector settings. Most importantly, the results primarily serve the purpose to support the development of clinical practice guidelines and interventions to promote smoking cessation in cancer patients to improve their cancer prognosis and in long-term, increase their survival time and quality of life. For the 280 cancer patients in the experimental group, we expect to help at least 81 to quit smoking at 6-month (29 %). For the sessions that are randomized as the experimental group, all cancer patients (no matter they participate or not into the study) would receive a specially designed leaflet and health warning from oncologists/ nurses. In addition, all the 580 subjects would receive a generic self-help booklet to help them quit smoking. Among the quitters who have lung cancer, their risk of cancer recurrence can be reduced by 20–47 %; the mortality rate (all-cause) can be reduced by 46–66 %; the risk of second primary tumor can be reduced by 76 % (among those with limited stage small cell lung cancer); and the likelihood of 5-year survival can be doubled, compared to still smokers [16]. Patients with cancer in other sites will also have clinical benefits after they quit smoking. Subsequently, the quality of life among cancer patients who stopped smoking can also be improved.

There are serval potential limitations or barriers of implementing the proposed intervention in clinical practice. First, the proposed intervention is relatively comprehensive, which generally takes 30 to 45 min to implement including the baseline assessment. According to our previous smoking cessation projects in outpatient clinics, some patients are too impatient to undergo a long intervention and some are reluctant to participate for fear that they might miss or experience delays in their medical consultation or other medical procedures. Nevertheless, the intervention will only implement during the waiting time for medical consultation in the out-patient clinics and all potential subjects will be reinforced by nurse counsellors that they will not miss the medical consultation or medical procedures through participating in this study. Second, the intervention that we proposed for the experimental group is not on a one-off basis. Each subject will receive at least one boost up telephone intervention within one week and another telephone intervention within one month by a nurse counsellor. Such practice may not be feasible in busy clinical settings in Hong Kong at this moment. Nevertheless, such approach is necessary and crucial as smoking is addictive and quitting is very difficult, with a high rate of relapse. Based on our previous smoking cessation projects on promoting smoking cessation, continuous reminding and offering support is of paramount importance to achieve the ultimate goal of complete cessation. Indeed, each telephone counselling will take only 10–15 min. If the telephone follow up effect size is proven and substantial, this would justify additional resources for such practice. In the short run, smokers may be referred to smoking cessation hotline for continuous support and follow up after receiving the initial intervention by healthcare professionals. Third, we do not use biochemical indicator as the primary outcome, which is more scientific and objective to ascertain whether a person has successfully quitted smoking. Nevertheless, using biochemical validation is costly, difficult to obtain for all subjects, and may not correspond to the time frame of the assessment. Furthermore, the response rate for participating in biochemical validation is far less than self-report; this situation is not only in Hong Kong but also has been reported in elsewhere [29]. In fact, subjects might refuse to comply with a biochemical validation for a wide variety of reasons unrelated to smoking status, continuing to classify all these subjects as smokers would represent a distortion of the outcome data, resulting in a gross overestimate of smoking rates. After that, we decide to use self-reported 7-day point prevalence quit rate as the primary outcome.