Effectiveness of a community-based multicomponent lifestyle intervention (the ADA programme) to improve the quality of life of French breast cancer survivors: protocol for a pragmatic cluster randomised trial and embedded qualitative study

Abstract

Introduction

Breast cancer survivors (BCSs) are often faced with multiple mental and physical sequelae and are at increased risk of emotional distress, degraded health-related quality of life (HRQoL), chronic pain and fatigue.

Physical activity is strongly associated with improved HRQoL and survival rates; however, adherence rates to recommendations for a healthy lifestyle are seldom satisfactory among BCSs. Also, few studies have examined the effectiveness of multicomponent and personalised interventions that integrate physical activity and motivational techniques to improve the HRQoL of BCS.

Method and analysis

“Activité physique adaptée Doublée d’un Accompagnement d’après cancer” (ADA) is an integrated programme of physical activity enriched with a dietary and supportive care approach targeting BCS in the early post-treatment phase. The effectiveness of the ADA intervention will be evaluated using a cluster randomised controlled trial design with two arms (ADA programme vs usual care; 1:1 ratio).

The ADA intervention aims to recruit 160 participants and will be implemented by Siel Bleu, a non-profit association specialised in health prevention via adapted physical activity. Measurements will be performed at baseline, 3, 6 and 12 months after the start of the intervention. The primary outcome will be participants’ HRQoL, at 12 months measured by the Functional Assessment of Chronic Illness Therapy-Fatigue global score. Secondary outcome will include participants’ physical, social, emotional and functional well-being. The effect of the intervention on physical activity level, motivation for physical activity, relation to food and self-efficacy will also be evaluated.

Ethics and dissemination

The study was approved by the ‘CPP Paris XI’ Institutional Review Board on 5 May 2022 (Ref no.: 21.04512.000048-22004). The study’s findings will be shared through various channels, including academic publications, simplified reports for wider audiences and active engagement with medical and institutional organisations as well as patients’ associations.

Trial registration number

NCT05658341.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• The stratified cluster randomised design will limit contamination and maximise balance between the two randomised groups; the primary outcome, health-related quality of life, is of value to breast cancer survivors and will be assessed both at short-term and long-term (9 months after the end of the intervention).

• A qualitative and economic analysis is embedded in the study.

• Double blinding is not feasible, but several measures have been taken to prevent recruitment, performance and detection bias.

• The pragmatic design of the intervention will facilitate future generalisation.

Introduction

Worldwide, breast cancer (BC) is the most commonly diagnosed cancer, with around 2.3 million newly diagnosed cases each year, accounting for around 1 in 4 cancer diagnoses in women.¹ Despite it being one of the leading causes of cancer death among women, survival following a BC diagnosis has greatly increased in high-income countries.² As a result of advancements in early detection and treatments, the 5-year survival rate has risen well above 80% in most European countries (87% in France), for all stages combined.^{3 4} Although the number of women who survive BC is increasing, those women often suffer from psychological and physical problems, in part due to the long-term and late effects of cancer treatment(s).^{5 6} Emotional distress, depressive symptoms, anxiety, fatigue and pain are commonly experienced by breast cancer survivors (BCSs), who usually have a diminished QoL compared with the general population.⁷,⁹ Hence, improving the QoL of BCS has been the focus of a great deal of research during the past decades.

Numerous randomised controlled trials (RCTs) have shown that exercise programmes combining aerobic and endurance exercises improve physical functioning, mental health and overall health-related quality of life (HRQoL) and reduce/mitigate cancer-related fatigue among women with BC, both during and after treatment.¹⁰,¹² Moreover, evidence from observational longitudinal studies suggests that physical activity may decrease the risk of recurrence and improve overall and specific survival with a positive dose-response relationship.¹³ In recognition of these benefits, exercise prescription guidelines for clinicians and physical activity professionals have been issued,¹⁴ and adopting and maintaining an active lifestyle is part of the recommendations for women with BC, along with eating a healthy diet and avoiding smoking.¹⁵ The European Society for Clinical Nutrition and Metabolism (ESPEN) therefore emphasises the importance of regularly evaluating the nutritional status and weight fluctuations in patients with cancer. They also stress the implementation of early nutritional interventions, incorporating diets enriched in energy and protein.¹⁶ ESPEN also recommends for patients with cancer to either maintain or increase their level of physical activity, to support muscle mass, physical function and metabolic patterns.¹⁶

Despite the large body of evidence on the safety and benefits of physical activity on BC outcomes, women typically diminish their physical activity commitment as their treatment progresses, as well as within the first years after treatments.¹⁷ And it has been estimated that only 10%–20% of BCSs follow physical activity recommendations (ie, at least 120–150 min per week of moderate-intensity to vigorous-intensity physical activity) 5 years after diagnosis.^{18 19} Even in RCT of exercise interventions, participation rates and adherence to the intervention (when reported) are often suboptimal (ie, mean participation rate is around 60% and mean sessions attended is between 63% and 78%).²⁰ Furthermore, both interventions and follow-up times are generally relatively short, and the long-term (ie, beyond 6 months postintervention) effectiveness of interventions on physical activity behaviour and HRQol is unclear.

Physical activity initiation and maintenance are particularly challenging for BCSs who face multiple barriers to practice including physical (fatigue, increased weight and other cancer-related physical symptoms), environmental/organisational (time constraints, lack of information/knowledge and inadequate facilities) and psychosocial (lack of motivation, low social support or self-confidence).²¹,²⁴ Main motivators reported were body image, positive physical benefits, improvement in psychological well-being, increased self-esteem, empowerment and social support.²¹,²⁴

Little is known about the best strategies to encourage BCS to engage in physical activity and sustain a physically active lifestyle. Existing RCTs on physical activity during and after treatment comprise home-based, telephone-supported as well as supervised and unsupervised interventions.^{25 26} A systematic review and meta-analysis of RCT targeting physical activity behavioural change in recent post-treatment BCS found that highly structured interventions involving more intense supervision/monitoring (ie, in-person, frequent interaction) tended to produce larger effects than those who are predominantly unsupervised or home based, although it was noted that many larger effect sizes also came from interventions supported by phone counselling or email.²⁷ The findings of several meta-analyses of qualitative research which have explored BCSs’ individual, lived experiences of participating in a supervised exercise intervention^{23 24 28} provide additional useful information to guide the development of effective programmes. In particular, many participants perceived that exercising with other women who had similar cancer experiences and having an exercise instructor who was knowledgeable of their physical limitations increased their motivation to join and adhere to the exercise programme. This suggests that both the group element and the quality of supervision are important to BCS. A recent systematic review of physical activity interventions in women with BC further indicates that group-based interventions may provide additional benefits (eg, a greater increase in physical activity level and/or improvement in QoL), as compared with individual interventions.²⁹ But this conclusion cannot be drawn definitively due to the low quality of several trials, the limited number of group-based interventions and the overall lack of evidence of long-term intervention effects.

A number of psychological theories and techniques related to motivation have also been used to enhance exercise uptake and adherence in BCS.^{30 31} These include the theory of planned behaviour, social cognitive theory, self-determination theory and transtheoretical model. In addition to these theoretical frameworks, intervention programmes have made use of various strategies like self-monitoring, social support, problem-solving and participative goal-setting to enhance uptake and adherence. Motivational interviewing, in particular, has been considered as a very promising method to promote sustained positive lifestyle changes, in particular physical activity improvement.^{31 32} In a systematic review and meta-analysis of RCT targeting physical activity behavioural change in recent BCS, the authors found evidence to suggest that the extensiveness of the use of theory-related behavioural change methods enhanced intervention effectiveness.³³ Reviews of studies that examined the effectiveness of non-pharmaceutical interventions (physical activity and/or psychological) for improving the HRQoL of adults with cancer further indicate that physical activity interventions that integrate behavioural change/motivational techniques (in particular cognitive-behavioral therapy) generally have positive effects on the HRQol of BC and other cancer survivors.^{26 34 35} However, the effectiveness of such combined and necessarily complex interventions as compared with individual interventions is unclear. In particular, the added value of complex interventions as compared with exercise training alone has not been established since their effectiveness has generally been established in comparison with a control group who received no treatment (usual care/waitlist controls). Given that exercise is now considered an imperative support for BC management, it would seem important from a scientific as well as ethical point of view that future studies compare the effectiveness of complex interventions to exercise alone, especially under usual practice conditions (ie, in pragmatic trials). Furthermore, it is difficult to draw a definite conclusion regarding which interventions are most successful and for whom. Indeed, interventions are usually poorly described, outcome measures vary and cancer populations are often heterogeneous (mix of BC and other cancers, adults at different stages on the cancer continuum of care and period of time since completion of treatment of varying length). Further research is also needed to better understand the mechanisms through which behavioural change occurs so that the results can be used to design and implement future behavioural change interventions. Mediation analyses that allow to examine the link between the behavioural change strategy and determinants of physical activity (eg, self-efficacy) with regard to intervention effectiveness would be helpful in this respect.³³

Multicomponent and comprehensive interventions that help BCS build healthy habits (eg, active lifestyle and healthy eating) while addressing women’s psychosocial needs (eg, social support and chronic stress/anxiety relief) are likely to be the most successful in improving BCSs’ QoL, a hypothesis congruent with the tenets of integrative oncology,^{36 37} and supported by the findings of our qualitative study on women’s experiences of life postbreast cancer treatment, as well as of a number of qualitative studies conducted in patients with cancer in general.³⁸,⁴⁰ In this perspective, integrating stress reduction tools, such as progressive muscle relaxation and deep breathing techniques, into conventional exercise programmes may provide additional benefits in terms of reduction of fatigue and improvement in emotional well-being and overall HRQoL.^{36 41} These stress reduction tools are key ingredients of cognitive behavioural therapy as well as ‘body-mind’ practices such as yoga and mindfulness-based interventions, which have all been shown to improve mental health and QoL of patients with BC and survivors, at least in the short term.⁴²,⁴⁴ In addition, support for the initiation and/or the continuation of physical activity combined with a balanced diet is becoming increasingly important in therapeutic patient education (TPE) in cancer therapy. According to WHO,⁴⁵ TPE aims to ‘help patients acquire or maintain the skill they need to best manage their lives with a chronic disease’. It is a person-centred approach that differs from traditional patient education in the self-management skills conferred to the patient. Several cancer-specific programmes of TPE have been developed to help patients with cancer manage symptoms (fatigue and pain), side effects of treatment or compliance with treatment. Although few have been thoroughly evaluated, there is evidence to suggest that TPE interventions improve anxiety, depression and psychological distress in older patients with cancer (over 65 years old) and treatment adherence.^{46 47} However, there are yet limited data on the potential benefits of TPE on lifestyle behaviours, in particular on physical activity practice.^{38 39 48} The challenge of TPE interventions targeting lifestyle changes (regular physical activity and healthy diet) is to integrate these new health practices into usual cancer care, including the post-treatment surveillance phase. However, the effectiveness of this type of support system, particularly in terms of whether or not a healthy lifestyle is maintained beyond the intervention period, outside of the hospital setting, and the durability of the positive effects on health and HRQoL, has not been established, especially in the context of BC and exercise interventions.

In conclusion, there is a need for developing and evaluating more comprehensive, multicomponent and personalised lifestyle interventions which take into account the needs, expectations and preferences of women following BC treatment. Interventions that combine group-based exercise and a person-centred educational and motivational approach to lifestyle change appear particularly promising, as they are likely to improve adherence to recommendations and the effectiveness of existing interventions. However, to be widely deployed and to benefit the greatest number of women possible, they must be relatively simple to implement and carried out in the usual conditions of practice (particularly outside hospitals and cancer care centres) and take into account the costs to society. They also need to have a durable effect, which extends beyond the intervention period.

To meet all these challenges and needs, we developed the Activité physique adaptée Doublée d’un Accompagnement d’après cancer (ADA) (ie, Adapted physical activity coupled with a postcancer support approach in English) programme, an integrative intervention combining group-based workshops of adapted physical activity incorporating relaxation and breathing techniques with a lifestyle-oriented therapeutic education approach designed for BCS in the early post-treatment phase. The main purpose of this 12-week programme is to induce positive and sustainable changes in women’s attitudes and practices regarding physical activity and diet for long-term improvement of their QoL and long-lasting health benefits.

The ADA study aims to examine the immediate and sustained effects of the 12-week ADA programme on the HRQoL of BCS, overall and in its various dimensions (physical, emotional, functional and social well-being) and on health practices and related measures (physical and sedentary behaviour, motivation for physical activity, anthropometrics, relation to food and perceived self-efficacy with regard to health behavioural changes) in comparison with a 12-week standard postcancer exercise programme (considered as usual care). Our primary interest is in the long-term effects of the intervention. We hypothesise that women in the intervention group will have a better overall HRQoL (primary outcome) and more favourable health-related parameters (in particular, a higher physical activity level) at 12 months of follow-up (ie, 9 months postintervention) than women in the control/usual care group. A final exploratory aim is to determine the extent to which any positive effect of the intervention on the HRQoL is mediated by factors such as women’s motivation for physical activity, relation to food or self-efficacy.

The ADA study has been codesigned by a multidisciplinary team of researchers with different expertise (cancer epidemiology, interventional and public health research, sociology and philosophy of health, and healthcare ethics), with a contribution of health professionals specialised in clinical oncology and cancer supportive care, and in partnership with Siel Bleu, a non-profit association specialised in adapted physical activity, that is, physical exercises tailored to the needs, possibilities and expectations of specific population groups such as people with a chronic disease or disability or old adults.^{49 49} The ADA programme builds on Siel Bleu experience in developing and testing innovative postcancer supportive care programmes centred around adapted physical activity, and it will be implemented by the Siel Bleu network of qualified professionals, in usual practice conditions. This pragmatic approach is intended to facilitate transfer of the results into practice and implementation at the scale of the ADA programme in case a significant added value of this programme is demonstrated.

A qualitative study is embedded in the ADA trial. Interviews of both participants and instructors will be conducted to better understand the experience of women and physical activity professionals with regard to the interventions. This reflexive approach holds promise to adapt and improve the ADA programme for even greater benefits for BCS. An economic analysis of the intervention will also be conducted to assess its costs (direct and indirect) from the perspective of the public payer.

Methods

Study design

We will conduct a cluster randomised controlled trial to assess the effectiveness of the ADA programme (intervention) as compared with a standard postcancer physical exercise programme (control/usual care) at a 1:1 ratio for the two comparison groups or trial arms. A cluster corresponds to a small group of women who follow the same exercise programme (ADA programme/usual care) delivered by the same instructor. Based on our sample size calculation, a total of 20 clusters, each comprising an average of 8 women, will be formed in 10 geographical sites located in different cities and regions of Mainland France where Siel Bleu already implements community-based physical activity workshops for cancer survivors. Figure 1 summarises the design of the ADA trial and shows the chronological sequence of the trial’s implementation steps in each study site.

Figure 1. The ADA cluster randomised controlled trial design.

The provision of cancer-related supportive care for improving the HRQoL of patients with BC, such as psychological support, pain management, dietary support or adapted physical activity workshops, has increased significantly in France since the national 2003–2007 Cancer Plan. However, large geographic disparities in supportive care provision still exist, and these disparities are not necessarily related to the size of cities or to the size or nature (public vs private) of the local hospitals or cancer treatment centres. Thus, to limit potential bias stemming from differences in supportive care provision between study sites, we plan to form two clusters in each geographic site: one cluster will receive the ADA programme, while the other will receive usual care. Based on the expected enrolment speed (as assessed based on the current speed of formation of the patient queue in the selected study sites), these two exercise groups will be created in two successive waves of recruitment, each lasting up to around 4 months.

The order of the two exercise groups is as follows: which of the first or second group formed will receive the ADA programme will be determined at random prior to the beginning of the recruitment period in each site. In other words, cluster randomisation will be stratified on study site, and participants will be assigned chronologically to one of the two exercise groups according to the time of their recruitment.

The intervention phases of the two clusters (ADA programme/usual care) will not overlap, and the two exercise groups will be run by two different Siel Bleu instructors, which should prevent contamination bias due to participants changing exercise group or instructors modifying their practice. Measures taken to prevent selection/recruitment bias as well as contamination/performance bias are detailed in sections below (see ‘Randomisation and blinding’ and ‘Intervention implementation’).

Each woman will be followed up during 12 months through self-report questionnaires delivered at the beginning (baseline) and the end (at 3 months) of the intervention and then at 6 and 12 months. Data regarding primary and secondary outcomes will be assessed at each time point.

The ADA trial started in October 2023 (the start of the recruitment phase in the first study site opened) and will end after all women from the last cluster formed in the last site opened will have been followed for 12 months. In a given study site, the trial’s implementation is planned to last approximatively 20 months, depending on the efficiency of the recruitment phase.

Participants

Inclusion/exclusion criteria

Participation in the trial will be proposed to any women aged 18–72 years, with a diagnosis of localised BC of any type and who have completed their initial treatment (surgery, chemotherapy and radiotherapy) for less than 15 months. Given the duration of hormone therapy (at least 5 years), participants may still be undergoing hormone therapy. They may also be nearing the end of their anti-Her2 therapy treatment. In addition, participants must be French speaking and covered by the French Social Security system or be a beneficiary of a similar health insurance system, as required by the French law governing medical research. Physically active women, whatever their type of activity (individual or supervised/group based), are eligible to participate. This is in keeping with our pragmatic approach and intention to assess the effectiveness of the ADA programme in habitual practice conditions in community settings.

Women will not be included if they have a cancer diagnosis other than BC, a relapse/metastasis of BC, generalised cancer, a medical contraindication to exercise or a significant visual, auditory or cognitive problem (as assessed by Siel Bleu instructors) which makes it difficult to participate in group physical activity workshops. Women who are participating in another clinical trial or who plan to move away from the study site before or during the planned intervention period will also be excluded. Men are excluded from our study to optimise group homogeneity, especially regarding the HRQoL measures.^{50 51}

Recruitment process

Siel Bleu will recruit participants based on recommendation or referral from various local partners (hospitals, cancer treatment centres, the French League against Cancer, community health and social services, etc) according to usual practice. Potential participants may also be recruited through advertisements (printed posters and flyers), as well as through cancer-related groups or events.

A preinclusion questionnaire will be filled out when the local Siel Bleu instructor first contacts a woman, which will allow to verify inclusion criteria and to document non-participation. The study will then be presented in more detail to eligible women. An information letter along with an informed consent form will be sent (by mail or email) to interested women. The signed informed consent form will then be collected by the instructor at the beginning of the intervention.

Randomisation and blinding

Randomisation will be stratified by site with a 1:1 ratio for the intervention and control groups (10 study sites, 2 clusters per site). It will be performed using the blockrand function of the R package ‘blockrand’ by an INSERM researcher (FEK) who will forward the cluster allocation sequence (ie, which of the ADA or control exercise group to be formed will be the first to start) to the local Siel Bleu investigators prior to the beginning of the recruitment period in each site.

To avoid potential selection bias, local partners involved in participants’ recruitment will not know which of the two exercise groups (intervention or control) is in the making at the time they direct women to Siel Bleu or when the intervention is going to begin. All potential participants will be informed that the trial aims to compare two different support care programmes that both involve adapted physical activity and will receive complete information regarding the specific programme they will follow if they consent to participate. They will not know the exact content of the other programme or which one is the intervention to be evaluated and which one is the comparator.

Outcomes

The primary outcome will be the HRQoL at 12 months, as measured by the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) global score. This score is based on the 27-item Functional Assessment of Cancer Therapy-General (FACT-G) scale which measures four primary HRQoL domains in patients with cancer: physical well-being, social/family well-being, emotional well-being and functional well-being. Additionally, the 13-item FACIT-F scale provides self-reported data on fatigue, a major factor linked to diminished QoL among BCS.^{52 53}

Secondary outcomes will be measured at 12 months of the following parameters: participants’ physical, social, emotional and functional well-being as measured by the four subscales of the FACT-G^{52 53}; self-reported fatigue and its impact on daily activities and function (FACIT-F); physical activity level measured with the short version of the International Physical Activity Questionnaire⁵⁴; motivation for physical activity assessed with the short version of the Behavioral Regulation in Exercise Questionnaire-2 scale⁵⁵; sedentary behaviour (sitting time) measured with a questionnaire adapted from the Recent Physical Activity Questionnaire⁵⁶; body weight and waist circumference; relation to food, adapted from the Positive Eating Scale⁵⁷; and self-efficacy with regard to health behavioural change, assessed by an ad hoc scale.

Measures of primary and secondary outcomes will be collected using the same instruments at all time points (see figure 1figure 1).

Data collection

The baseline questionnaire and questionnaire at 3 months will be handed to participants by the Siel Bleu instructor during the physical activity workshops, whereas the questionnaire at 6 and 12 months will be sent to participants by the study’s project manager. Participants will be instructed to complete each questionnaire at home and then return it to the study’s coordination team (at Inserm) in the accompanying prepaid and preaddressed envelope.

In addition to the outcomes, self-reported data will be collected on sociodemographic variables: regular physical activity prior to BC diagnosis (at baseline only); tobacco and alcohol use (at baseline and 12 months); participation in supervised adapted physical activity classes (other than those offered by the ADA study) including alternative forms of exercise such as yoga, Qigong, etc (at baseline and 3 months); satisfaction with the intervention received (ADA programme/usual care) (at 3 months); and participation in supervised physical activity classes (whether organised by Siel Bleu or another physical activity provider) after the end of the intervention (at 6 and 12 months).

Interventions

ADA programme

The development of the ADA programme and its analysis is based on a theoretical framework about people’s experience of adapted physical activity in chronic disease.⁵⁸ This framework was elaborated during the first French TPE intervention for BCS that was developed by Siel Bleu association in partnership with Curie Institute, a large cancer treatment centre in Paris.⁵⁹ This framework mobilises philosophical and sociological concepts useful to understand people’s experience of lifestyle changes recommended after cancer. We saw that, for them, these changes constitute an important daily life revolution that demands a real comprehensive, caring and empowering approach.^{38 39} The ADA programme is an integrated and multimodal programme with adapted physical activity at its core. It also includes educational and motivational components, incorporating techniques from TPE, and is delivered at both the individual and group levels. Developed with the intention of better addressing the needs of BCS’s for comprehensive support, the ADA programme aims to help women become more autonomous in their self-care, in particular by adopting an active lifestyle.

The content and timeline of the ADA programme are described in figure 2. The 12-week programme will include weekly 1 hour workshops of adapted physical activity including exercise of moderate intensity as per current recommendations.^{14 16 60 61} Each workshop will end with a discussion of relaxation techniques and the undertaking of breathing and deep muscle relaxation exercises. A series of ‘minute for nutrition’ short information leaflets will also be distributed and discussed at the end of each workshop. These leaflets, based on booklets of the National League Against Cancer and the INCA (French National Cancer Institute), will provide advice on eating a healthy diet and address different nutrition-related themes relevant to BCS. In addition, two workshops about ‘living well after breast cancer’ will be offered: one on movement and general mobility during daily activities and the other on daily nutrition. Based on discussions and disclosure of personal experiences from the participants, these workshops will be led using TPE techniques.

Figure 2. The ADA programme.

A 45 min individual assessment will take place before the first physical activity workshop, to allow the evaluation of participants’ experience of physical activity, postcancer experience and motivation. This will enable the personalisation of the intervention which will take place in small groups after the baseline assessment. In addition, women will be asked to set personal challenges as a method of motivational reinforcement. They will then be called twice during the physical activity cycle, for about 15 min each time, to further motivate them and personalise the programme and to receive their concerns or remarks. These additional individual assessments throughout the intervention, as well as shared experience during group discussion workshops, will allow us to further adapt the ADA programme to the needs and expectations of participants. A final 30 min follow-up call will be made to each participant after the last physical activity workshop which will include discussion about ways to maintain regular physical activity beyond the intervention. The protocol of the entire ADA programme has been precisely described in the instructors’ training manual.

In addition, participants of the ADA intervention group will have access to a dedicated internet space containing several documents and videos on topics of concern to patients during the post-treatment phase (sleep, returning to work, weight gain, well-being, etc). They will also have references to various other media such as books, comics and films depicting different aspects of life after cancer and to online exercise sessions to complement the group workshops. The link to the online platform is exclusively provided to participants in the intervention group after their individual assessment at baseline.

Comparator

Participants in the control group will be offered weekly 1 hour workshops on adapted physical activity for 12 weeks. The workshop’s content is adapted to people who have been treated for cancer and are based on current recommendations.^{60 61} Such sessions are commonly organised by Siel Bleu in hospitals, community groups or local committees of the French National League Against Cancer.

Intervention implementation

Workshops in the intervention and the control groups will be implemented in community settings such as local associations or community centres. These workshops will be entirely carried out by instructors who are regular Siel Bleu employees. These instructors are all specialised in adapted physical activity and have a bachelor’s (Bac+3) or a master’s degree in this domain. All instructors are therefore trained in methods of adapting physical activity workout to the capacities of each participant in order not to set him/her back while allowing him/her to progress.

The instructors in charge of supervising the ADA intervention groups have received a minimum of 40 hours of additional university training in TPE techniques. They will lead all the workshops and will also ensure the initial individual assessment of the women included in their respective exercise group (cluster) as well as the three individual monitoring phone calls that take place during and at the end of the intervention.

All study instructors will be specially trained in the implementation of the study. Instructors who will deliver the ADA programme will receive additional training on how to implement the ADA programme and will be asked not to discuss its content with their counterparts in charge of implementing the usual care exercise workshops in the same study site.

In each study site, the intervention (ADA programme or usual care) will begin as soon as a group of eight women is formed or at the end of the recruitment period as long as a minimum of five women have been enrolled. A maximum of 11 women per group has been set, which may compensate for possible small groups in some sites. Once the first group has started, inclusions for the second group will begin (see figure 1).

As part of the pragmatic trial approach, ensuring our study closely mirrors real-life conditions, participants will also have the opportunity to engage in complementary activities and consult other healthcare and wellness professionals.

Process evaluation

To examine the quality of the intervention implementation which might affect the study outcomes, we will be carrying out a process evaluation. Therefore, we will be documenting all activities related to the ADA intervention continuously during the intervention phases in each site, in order to assess the fidelity and quality of implementation. Participants’ attendance at the workshops will be systematically recorded by the instructors, and the average number of workshops followed in the two groups (ADA programme/control) will be compared by study site and overall.

Patient and public involvement

Patients with BC who have previously participated in various exercise and supportive care workshops organised by Siel Bleu have been solicited to review the overall ADA programme content and to select the various media resources included in the ADA-dedicated internet space with Siel Bleu investigators.

Statistical analyses

Sample size calculation

The primary outcome is the HRQoL, as measured by the FACIT-F global score at 12 months. The score varies between 0 and 160, with a higher score denoting a better HRQoL. We hypothesise that the mean score in the intervention group will be 10 points higher than in the control group at 12 months.^{51 62} Assuming a significance level of 5% (α=0.05), a power of 80% (β=0.20), a SD equal to 9 and an interclass correlation up to 0.5, a total number of 16 exercise groups (clusters) of 8 participants on average is required (calculated with the R package CRTSize and the function ‘n4means’).⁶³ We also hypothesised a 25% loss of follow-up rate. Thus, we will recruit 160 participants in total, divided into 20 exercise groups (clusters) of 8 participants, that is, 80 participants in each comparison group (intervention vs control).

Statistical analysis plan

For the primary analysis, we will compare the difference in means of the FACIT-F global score at 12 months between the two groups with a Student’s t-test. We will also model the effect of the randomisation group in the variation of the FACIT-F global score using a multivariable linear regression with a random effect (mixed model) to take into account the study design and repeated measures. This will allow us to examine within group and between groups changes in HRQoL at different time points over the 12-month follow-up. We will follow the same statistical analysis plan for the secondary endpoints. Depending on the outcome’s distribution, we will perform multivariable linear or logistic regressions with a random effect (to account for study design) to model the effect of the randomisation group on the outcome considered. We will be testing the potential mediating role of several variables, including motivation to engage in physical activity, relation to food or self-efficacy, to provide insight into ‘why’ the intervention works. We will perform mediation analyses⁶⁴ to quantify the effect of each of the potential mediating variables in the relationship between the randomisation group and the HRQoL.

Qualitative study

Semistructured interviews will be conducted with a sample of study participants and with all instructors across both the intervention and control groups. Around 20 participants will be chosen by instructors to reflect different profiles in terms of age groups, social background and place of living (urban, semirural and rural). Interviews will be conducted by one of the researchers involved in the study, reminding the study participants that they are completely free to accept or not the interview, the content of which will remain confidential (as specified in the notice and participant’s consent form). Interviews of participants will allow to collect information regarding the following: how they perceived the programme’s presentation; their interest and initial motivation for participating; how they perceived the programme’s general interest, its benefit(s), limitation(s) and potential negative effects; the evolution of their physical activity practices and way of life following the programme; their interest and motivation to continue practising physical activity; their general opinion on physical activity, diet, health and cancer; and how to prevent cancer.

Interviews of study instructors will allow us to collect data on the following: their experience with the programme; the difficulties encountered and the perceived facilitators; their insights into participants’ perceptions and motivations; their opinion on the programme, its general interest and its limits; their views on life after BC, prevention and behavioural changes which can be fostered; their views on their role in the programme and in health prevention; and the relationship with the participants.

Interview guides are available in online supplemental material. All interviews will be recorded and fully transcribed. The analysis will follow the inductive method of the Grounded Theory proposed by Strauss and Corbin⁶⁵ and continue until data saturation is achieved, ensuring a comprehensive understanding of the different perspectives involved, both from participants and instructors.

Medicoeconomic evaluation

We will perform a medicoeconomic analysis according to the methodological recommendations of the French National Authority for Health.⁶⁶ The medicoeconomic analysis will be an analysis of costs from a societal perspective, including direct and indirect costs with a 1-year time horizon. We will also assess the relevance of performing a cost-consequence analysis, which consists of listing the different costs and benefits of the two interventions in the two randomisation groups. This type of analysis is relevant if it is not possible to evaluate the costs and/or benefits in monetary terms.

Ethics and dissemination

The study was approved by the ‘CPP Paris XI’ Institutional Review Board on 5 May 2022 (Ref no.: 21.04512.000048-22004). The study’s findings will be shared through various channels, including academic publications, simplified reports for wider audiences and active engagement with medical and institutional organisations as well as patients’ associations.

Expected results and potential impact

This trial aims to provide scientific evidence of the ‘real-world’ effectiveness of an easily generalisable prevention programme to promote sustained positive lifestyle changes and improve the QoL of BCS and thereby to best respond to the needs of an ever-growing number of women living beyond BC treatment. We, therefore, hope that the results of this trial will bring compelling evidence that will warrant large-scale dissemination and implementation of the intervention. One of the advantages of the pragmatic approach and collaboration between professionals and researchers in the ADA project is that the intervention will be readily available for larger dissemination using Siel Bleu’s existing infrastructure and network.

Data availability statement

Data are available upon reasonable request.