The OncoAppstore is, to our knowledge, the first platform to offer cancer-specific and cancer-relevant self-management applications for people directly affected by cancer and their relatives. In this case, it is specifically developed for the Dutch cancer population to improve access to these applications. This study, as part of the real-world OncoAppstore study, provides the first insights into the sociodemographic and HRQoL of the OncoAppstore user population.

In the first 15 months, 3620 users requested a health credit and purchased 4333 applications. On average, users utilised €53 of the available €100 health credit. Given that the implementation of healthcare interventions is estimated to take approximately 17 years, we are satisfied with the number of users reached in the first 15 months and expect a continued steady increase in user adoption going forward [30,31,32,33]. Users were predominantly highly educated females diagnosed with breast cancer who seek applications targeting cancer-related fatigue. Clinically significant distress was reported by the majority of users and approximately half indicated experiencing substantial functional impairments and expressed a need for support. Most users were employed before diagnosis, though many were on sick leave or retired afterward. Symptom burden was highest for fatigue, pain, and nausea/vomiting.

Previous research has highlighted disparities in healthcare utilisation, unmet needs, and health-seeking behaviours among people directly affected by cancer [34,35,36,37,38,39,40]. The use of healthcare services and/or health technologies is often associated with younger age, female gender, higher education level, employment, receiving chemotherapy, and higher levels of distress and depression [34,35,36,37,38,39,40]. Research suggest that age and distress are interrelated due to the responsibilities inherent to different life stages. Managing work and a cancer diagnosis can increase the need for additional support [37]. Similarly, gender and distress are interrelated. There are differences between men and women, both in levels of stress as well as coping strategies. Women experience higher levels of stress and they have a more emotional-focused coping style [41]. This aligns with our findings, as the majority of users in this study were distressed, females, and employed prior to their diagnosis.

Furthermore, our user population received more surgery, chemotherapy, radiotherapy, hormone therapy, and targeted therapy compared to the Dutch adult cancer population, which could be related to the differences in tumour site and tumour stage. These differences may have contributed to an increased symptom burden. More treatment could also have led to more contact moments with healthcare professionals and/or fellow patients. This could have enhanced the relationship with healthcare professionals and knowledge of additional care services, both of which are known facilitators to access to additional care services [42].

Additionally, one specific application, Untire Now, which focuses on cancer-related fatigue, was purchased by two-thirds of all users who purchased an application [8]. This is consistent with our HRQoL findings as most users reported experiencing problems with fatigue, concentration issues, and cognitive functioning. Decision aids to support treatment-related decisions and applications focused on the period from diagnosis to the end of treatment are well represented in the applications offered in the OncoAppstore, as well as applications targeting breast-cancer patients. These applications specifically attract users who were recently diagnosed and/or had breast cancer, which is reflected in our user population.

We consider it probable that individuals engaging with the OncoAppstore, and self-management applications in general, exhibit more proactive help-seeking behaviour. Their engagement is likely driven by unmet needs, significant functional impairments, and/or a high symptom burden.

Additionally, previous research indicates that people directly affected by cancer have limited awareness of self-management tools and/or additional care services [19, 43, 44]. This lack of awareness appears to be more prevalent in older individuals with a low socioeconomic position and lower education levels [43,44,45], a trend that is consistent with our findings. In recent years, psychosocial care has increasingly become an integral component of the cancer treatment. With nearly 30% of our users who became aware of the OncoAppstore through a healthcare professional, guidance from healthcare professionals to appropriate additional care services is an important facilitator of self-management adaptation in our study population as well. Further integrating psychosocial care and increasing awareness of additional care services is warranted.

A strength of this study is the direct implementation of the OncoAppstore into a real-world setting, providing immediate access to self-management applications for all interested Dutch people directly affected by cancer and their relatives. The applications target some of the core issues that the majority of people directly affected by cancer are facing, such as cancer-related fatigue, pain, depressive symptoms, and improving lifestyle and knowledge [8,9,10,11,12,13,14,15,16,17]. Furthermore, to ensure quality, applications had to meet GGD assessment criteria, which include usability, reliability, privacy, and scientific foundation, before inclusion in the OncoAppstore [22]. The OncoAppstore operates within kanker.nl, a widely recognised online platform among people directly affected by cancer, their relatives, and healthcare professionals, attracting over one million visits per month and more than 39,500 users with an account. Unawareness of digital interventions and concerns over cost have been identified as barriers to self-management application uptake [19, 46]. By eliminating financial constraints and using a well-known platform, the OncoAppstore addresses these barriers, aiming to improve broader accessibility of online self-management tools. Insights from this study could further promote broader user inclusivity by specifically targeting the potential user not described in the user population of this study.

This study has several limitations. As part of an implementation project, the study period was predetermined rather than based on participant inclusion, and no sample size calculations were conducted. Additionally, participation in the study is voluntary for OncoAppstore users, resulting in sociodemographic, clinical, and questionnaire data being collected from only 10% of all users. This may introduce bias when characterising the user population and comparing users to non-users; e.g., it could be that specific groups of people directly affected by cancer, that are currently underrepresented in the OncoAppstore user population, do use the OncoAppstore but are less inclined to provide data. Moreover, the OncoAppstore appears to attract a distinct user population compared to the general Dutch cancer population. Efforts should be made to further enhance its visibility and extend its reach to engage more people directly affected by cancer who can benefit from self-management applications. However, the changing proportions of users who discovered the OncoAppstore through the platform kanker.nl versus healthcare professionals, friends and family, and other sources suggest that awareness of the OncoAppstore is already increasing. Additionally, one specific application focusing on cancer-related fatigue was purchased a lot more often than other applications [8]; thus, users of this application are overrepresented in this study. However, research shows that fatigue is one of the most common symptoms in people directly affected by cancer, especially in patients who receive chemotherapy and/or radiotherapy or patients with metastatic disease, where the prevalence of cancer-related fatigue (CRF) exceeds 75% [47]. Furthermore, data from the NCR of 2023 and 2024 concern preliminary data; hence, data from non-users is still subject to change. This study included solely completed registration from the NCR. The percentage of complete registrations from 2024 was 31%; for 2023, this was 81%, which is similar to the 84% from 2022 and 2021. This could explain some of the difference seen in time since diagnosis between users and non-users. Moreover, detailed data on application usage were not collected, limiting the ability to assess the effectiveness of specific applications or the OncoAppstore as a whole. As usage patterns vary between individuals, drawing definitive conclusions on impact remains challenging. Although, this allows users to personalise their selection and use of applications, reflecting real-world usage more accurately.

The OncoAppstore was created to enhance access to self-management tools for Dutch people directly affected by cancer and their relatives. During the first 15 months, users were primarily highly educated women diagnosed with breast cancer seeking applications targeting cancer-related fatigue. Findings from this study may offer valuable insights into the characteristics of users who are receptive to online self-management tools, contributing to the improvement of self-management infrastructure and its long-term integration into Dutch cancer care. Identifying characteristics of the users could help allocate resources to people directly affected by cancer who both need and seek this type of support, while recognising that others may require additional care and may be unwilling or unable to engage with digital tools. Notably, the OncoAppstore is not intended to replace care or reach all cancer patients and relatives in need of supportive care, but by providing self-management tools to those who are able to use it, we can potentially save scarce resources for those who are unable to profit from self-management alone. Further research is needed to evaluate the impact of the OncoAppstore on health-related quality of life and healthcare utilisation.