Mobile applications in radiation oncology—current choices and future potentials

Smartphones have revolutionized people’s lives, including the way they seek medical information [1]. In 2020, 78% of the worldwide population was in possession of a smartphone and the forecast predicts a further increase in the future [2]. There is a wide variety of health care applications (apps) for smartphones available. The top two categories are wellness management/fitness and disease management apps, whereas other categories include self-diagnosis, medication reminders, and electronic patient portal apps [1]. The World Health Organization (WHO) classifies such tools under the label mHealth or eHealth, and defines them as “medical and public health practice supported by mobile devices, such as mobile phones, patient monitoring devices, personal digital assistants, and other wireless devices” [3].

Cancer is a leading cause of disability and mortality worldwide [4]. Accordingly, a variety of cancer-focused apps exist and the number of research articles that study the use of apps in the field of general/clinical oncology is increasing [5]. The majority of health care professionals (HCP) are in favor of the use of oncological apps by patients according to Kessel et al. [6]. Moreover, the acceptance of mobile apps for the surveillance and follow-up of cancer patients undergoing radiotherapy is high [7, 8]. Indeed, there are several advantages like monitoring patient-reported outcomes (ePRO) and education of patients to increase compliance and optimize the HCP interaction. In addition, these applications can have positive psychologic effects by empowering patients, e.g., to track treatment, monitor side effects, or to schedule follow-up appointments [9].

Despite the large selection of apps in the field of oncology in general and the resonance in the scientific literature, little is known about their particular impact and use in the field of radiation oncology. Therefore, this review aims to summarize data on the scientific reception of apps in radiation oncology in the literature and to gain information on currently available apps for patients and HCP online.

A systematic review of the literature in the PubMed database and Cochrane Library was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [10] in August 2022 using the terms (“radiotherapy” OR “radiation oncology” OR “radio-oncology”) AND (“smartphone app” OR “mobile application” OR “app”).

To improve the retrieval rate of studies, the reference sections of eligible articles were additionally screened. Moreover, Google Scholar was searched using the identical search terms. To further enhance search output, a manual search was conducted within the table of contents of annual meetings of the European Society for Radiotherapy and Oncology (ESTRO), the German Society of Radiation Oncology (DEGRO), and the American Society of Radiation Oncology (ASTRO), including oral and (e-) poster contributions (past 10 years). Furthermore, ClinicalTrials.gov was searched using the same search terms to detect ongoing trials (search field: “all studies” and “other terms”).

Inclusion and exclusion criteria were defined before the search. Inclusion criteria were as follows:

Exclusion criteria were:

The respective PRISMA flowchart is given in Fig. 1.

Concomitantly, a search was conducted in the two major app stores to find commercially available smartphone apps. These two app stores were the Play Store (Android, Google; https://​play.​google.​com/​store) and App Store (iOS, Apple; https://​www.​apple.​com/​de/​app-store). Search terms were “radiotherapy,” “radiation oncology,” and “radiation therapy.” The search was carried out in August 2022 independently by two authors (S.J. and L.K.) using an iPhone 13 and a Samsung Galaxy S10. The respective PRISMA flowchart is given in Fig. 2.

Along with the increase in smartphone usage in all age groups, there is a growing interest in mobile health apps. Both HCP and patients are in favor of the use of oncological apps to support treatment adherence, to monitor side effects, and to improve communication [6, 7]. A body of research has been published focused on apps in the general/clinical oncological setting [5]. RT is an innovative, future-oriented discipline [48], representing a major pillar in cancer treatment and requiring special considerations. To our knowledge, this is the first review article to give a comprehensive overview of existing scientific literature on radiation oncology apps and the availability of commercial RT apps in major digital marketplaces.

In comparison to clinical oncology [5], our search revealed a limited number of research papers focusing on apps in radiation oncology. Of those, most studies consisted of a one-arm testing of a certain app or were descriptive in nature. Still, the vast majority of single-arm studies showed feasibility, high acceptance, and patient satisfaction. In the prospective two-arm studies with published results, apps showed improved exercise compliance in follow-up, with reduced adverse reactions for head and neck cancer [13, 15, 17] and increased compliance/communication in patients with prostate cancer [19] compared to the regular standard of care without the use of an additional app. However, the positive impact was largely limited to improving symptom control/reducing side effects. These results are in line with a study of Osborn et al. reviewing mHealth apps of patients with cancer (no special focus on RT). Their overview article included 17 studies with smartphone apps or internet portals collecting data on symptoms or patient activity. In summary, they showed statistically significant differences in ePROs when symptom monitoring using an app was compared to usual care [49]. The authors concluded that apps might improve aspects of symptom control in patients with cancer, but there was only little evidence for impact on other outcomes (e.g., mortality, cancer-related morbidity, long-term outcomes) [49]. Another systemic review of studies on symptom management interventions in people with advanced cancer also showed web- and mobile-based interventions to be efficient in decreasing the overall physical symptom burden [50].

ePROs, as seen in the majority of articles analyzed in our review, are still collected in a generally uncoordinated fashion. In recent years, the European Organisation for Research and Treatment of Cancer (EORTC) has tried to provide guidance in terms of ePRO measurement [51]. However, the problem of unstandardized measurements has already been stated by Giordano et al. [52]. In comparison to laboratory data, there is no common terminology or a common standard for accessing and analyzing ePROs [52]. This is in line with our results showing a wide variety of ePRO measurements in different studies. Mostly, evaluation focused on possible symptoms according to the RT field, but no standard was defined. This also applies to the times of PRO measurements: some study groups focused on the time period during RT (ranging from multiple daily to once-a-week collections), while others gathered data exclusively after RT (during follow-up), or both.

In addition to their importance in clinical day-to-day life, the collection of ePROs or other data (e.g., blood pressure, heart rate, etc.) via apps might also be useful and convenient in randomized controlled trials (so called smartRCTs), especially in the field of radiation oncology [53]. While legal limitations concerning data protection might be a hurdle, apps could potentially reduce costs, study duration, and subjectivity bias [53]. However, to our knowledge, there are currently no existing smartRCTs in the radiation oncology research field.

Collection of app-based ePROs could also hold some disadvantages: Hauth et al. stated that strategies to handle the large amount of data are among the major challenges to be addressed in the future [34]. Moreover, in an early paper published in 2011, Cox et al. pointed out some concerns particularly for palliative patients, where personal contact and the intuition of experienced HCP play an important role. Some clinicians found the age of patients often too advanced, with concomitant rapid deterioration of their condition, to be able to genuinely participate in a study using e‑technology [11]. Still, we found several examples of encouraging results in elderly patient cohorts. Buergy et al. found app-based follow-up feasible in a patient group ≥ 60 years [20]. In the randomized study of Sundberg et al., median age was 69 years [19]. Mean ages of around 60 years were described by others [13, 31, 39]. In line with the demographic transformation and an increase in personal usage of smartphones in the age group ≥ 65 years [54], we believe that the elderly population benefits from technical innovations and should not be excluded.

However, one still has to take the concerns of Cox et al. about personal contact und its impact into account [11]. Nevertheless, the use of new technologies does not automatically imply the neglect of personal contact. On the contrary, apps can be an additional tool to enhance patient empowerment and to personalize the patient–HCP relationship. Future app developers should therefore aspire to these goals.

In 2019, Cunha et al. published a review of the literature on mobile apps for remote support of RT patients similar to our review and found only four articles in the English language [55]. We revealed significantly more publications (n = 38). Apart from the fact that our search was more comprehensive, this shows that the existing literature is increasing, reflecting interest in this topic. More than half of the articles found in our search had been published within the past 3 years.

In the second part of our review, we searched digital marketplaces for available radiation oncology apps. A similar attempt was carried out by the study group of Charbonneau et al. [9]. They included 123 apps for general oncology: 50% of apps focused on general information for cancer, followed by specific apps for breast cancer (15%) and skin cancer (7%). Interactive features, including the ability to monitor symptoms, side effects, and treatment, were found in 20% [9]. These observations were similar to the RT-specific results presented here. However, we identified more apps for head and neck cancer patients, which is probably due to the fact that these patients often receive RT/RCT. Lu et al. found 41 apps, with the majority (73%) being general health/pain symptom trackers, when searching app stores for oncological apps [56], which also confirms our findings. Another review article focused on the more specific topic of apps in radiation oncology and was therefore more comparable to our search [57]. In total, Calero et al. identified 31 apps. However, the study group also included tumor staging apps which are not specific to radiation oncology. After subtracting these apps, 13 apps which would have met our inclusion criteria remained. The fact that we identified 39 apps in our search further underscores the emerging interest in this topic in the past few years.

Interestingly, we found a great discrepancy between our search results in scientific literature and search results for existing apps in the two major app marketplaces. While the literature search mainly returned apps for patients (ePROs, information, reminder, and workflow management), the two major app stores contained only four patient-centered apps (three for information/teaching and one workflow management). Only for one app found in app stores was a corresponding scientific publication found. On the other hand, 18% of scientific research articles dealt with an app that was available commercially. Most of those apps were not specifically designed for radiation oncology, but rather general health care apps tested in a radiation oncology setting. This was also seen in the review of Ana, where several apps tended not to be available after completion of the studies [5]. One reason for this discrepancy could be legal difficulties in setting up patient apps outside a clinical trial, with expensive accreditation procedures, e.g., CE marking or accreditation to the European Device Regulations (EU MDR), and reservations on data safety as well as an obligation to update information [58, 59]. Amortization of development, validation, and accreditation costs of RT apps may be facilitated by reimbursement frameworks with prescriptions for RT apps by the healthcare provider [59]. However, the potential target group for radiation oncology apps might be too small to compensate accreditation and maintenance costs. Nonetheless, the demand for digital education in radiooncology has increased since the beginning of the COVID-19 pandemic, especially among medical students [60‐62]. In conclusion, while more and more apps are being developed and tested, currently existing apps for HCP and patients found in app stores lack scientific background, whereas clinically validated apps do not become available through app stores or as prescribable medical products.

There are certain limitations to our study. First, in both parts of the review, i.e., the literature search and the app marketplace, search terms for general/clinical oncology were excluded. While beyond the scope of this review, we acknowledge that oncology apps could significantly contribute to advances in radiotherapy, especially for patients undergoing chemotherapy in addition to radiotherapy. Moreover, certain synergistic intersections between oncology and radiotherapy regarding the collection of ePROs (e.g., EORTC QLQ C30 quality of life forms) are conceivable.

Secondly, apps found in our research were downloaded for evaluation but not tested in full detail or even rated.

The current scientific literature provides some evidence for helpful apps in the field of radiation oncology, with a clear emphasis on apps for patients. The vast majority cover ePROs during or after RT. Most studies are single armed, showing the “feasibility” of tested apps without further randomized testing against standard of care. In contrast, app marketplaces mainly offered apps for dose calculations for HCP in the field of radiation oncology. Therefore, efforts directing the transfer of existing scientific research into the development of commercially available apps in the field of RT should be undertaken.

In pursuing this goal, creation of quality-assured apps for RT patients which combine information sources, ePROs during and after therapy, and the possibility of contact with an HCP would be desirable. Ideally, such apps could transfer highly standardized ePRO data to a hospital interface for easy analysis. Moreover, app development in the field of radiation oncology should involve a certification process of radiation oncology societies, with subsequent testing in trials. After successful studies, apps should be transferred for continuous support of patients and HCP outside the trials [5]. Furthermore, ePROs could also be used for app-accompanied clinical trials (smartRCTs) [53].