Breast cancer is one of the most common cancers in females worldwide, and is the leading cause of cancer-related deaths among females in developing countries [1]. In Korea, breast cancer is the second most common cancer in females [2]. In 2008, the incidence of breast cancer was 18.7 per 100,000 people, and it has since increased at an average rate of 6.6% per year [2]. Breast cancer is prevalent in females aged 15-34 in Korea, and as such, those affected are on average 10-15 years younger than in the United States [3-5].

Breast cancer has a relatively good prognosis, with an overall 5-year survival rate of 89.5%, and 98.2% in patients with stage 0. However, the 5-year overall survival rate of females with stage IV cancer is only 30.5% [6], highlighting the importance of detecting and treating breast cancer at an early stage. Females who practice breast self-examination (BSE) are usually diagnosed at an earlier stage than those who do not [7]. Mammograms and BSE are the most widely used screening methods for the early detection of breast cancer. In Korea, the National Cancer Center recommends monthly BSE for females older than 30 years and a mammogram every 2 years for females over 40 years of age [8].

In the Korean National Cancer Screening Survey of 1,255 females conducted in 2007, 88.0% were aware of BSE. However, the percentage of females performing regular or irregular BSE was very low (13.2% and 16.1%, respectively) [9], which is lower than in other Asian countries [10-12]. Appropriate interventions are therefore needed to encourage BSE. There have been previous attempts to achieve this, such as oral contraceptive packaging in the United States, and a short message service (SMS) in India, which have been used to encourage BSE, and both trials demonstrated positive results [13,14].

In recent years, the use of smartphones has been increasing rapidly. For example, in Korea, smartphone use accounted for 47.7% of the total mobile phone usage in 2012 [15], and the average time spent on a smartphone by users was 2.4 hours per day [15]. Due to the widespread use of smartphones, many mobile health applications for the management of chronic diseases, such as hypertension and diabetes, have been developed. As a result, more than 40,000 mobile health applications are now available on multiple platforms, and several studies of these have been conducted [16-19]. However, most of these mobile phone studies have focused on the management of chronic disease, for example, to help with weight loss or lifestyle changes [20,21].

Although the early detection of breast cancer is critical, no studies have attempted to facilitate BSE using a smartphone application. The aims of this study were therefore to develop a smartphone application promoting BSE, and to evaluate its effectiveness.

Fifty-nine subjects were initially enrolled in the study; however, 14 participants were eliminated from the analysis since they either failed to complete a questionnaire, could not be contacted, or did not reinstall the application after changing smartphones and upgrading the operating system. Overall, data from 45 participants were analyzed.

The baseline survey revealed that the average age of participants was 29.5 ± 5.9 years and that 60% (n = 27) of subjects were unmarried. Sixty-eight percent of participants were employed, while most (88.9%) had graduated from college or university. The prevalence of a family history of breast cancer was 4% (Table 1). Of the 45 enrolled subjects, 28 (62%) had previously performed BSE. Before using the application, only four subjects (8.9%) practiced BSE regularly, and only one participant (2.2%) knew the optimal time to perform BSE (Table 2).

Differences in the practice of BSE before and after use of the smartphone application were assessed. The number of subjects performing BSE increased from 28 to 32 (62.2% to 71.1%), although the difference was not statistically significant (p = 0.503). Subgroup analysis was then carried out based on the age, marital status, profession, and level of education of the participants. In the subgroup of users under 30 years of age, the rate of BSE practice increased from 36.4% to 81.8% after using the application (p = 0.002). In contrast, the rate of BSE practice in subjects over 30 years of age decreased from 87% to 60.9%. Other factors, such as marital status, profession, and education level, did not appear to influence BSE practice. We developed a function to induce BSE at the optimal time (7 days after menstruation onset). Overall, the practice of BSE at the optimal time increased from 2.2% to 33.3% (p < 0.001) (Table 3). The developed application has a function to encourage BSE through the daughter's stimulation. Actually, six participants (13.3%) performed BSE with their mothers using the "mother motivation function". The purposes of BSE are to detect the presence of an abnormal mass that requires additional evaluation and to motivate patients to go to the hospital. After practicing BSE using the smartphone application, four subjects (8.9%) detected an abnormal mass, which led to a hospital visit.

The results demonstrated that the use of the proposed smartphone application could increase BSE practice. In the baseline survey, most subjects were aware of BSE (86.7%); however, the number of participants who had ever practiced BSE was moderate (62.2%), and few of those (9%) performed BSE regularly. Interestingly, the rate of regular BSE is significantly lower than has been observed in other Asian countries, which ranges from 67.0% to 84.4% [10,11,22]. After using our mobile application, the overall BSE practice rate increased from 62.2% to 71.1%, and the practice of BSE at the appropriate time significantly increased from 2.2% to 33.3%.

There have been several previous attempts to encourage BSE. In the United States, BSE prompts on oral contraceptive packaging were encouraged, and after 3 months of intervention, the rate of appropriately timed BSE increased from 24.5% to 68.1% [13]. Although the application resulted in increased BSE, it required the cooperation of pharmaceutical companies, which cannot easily be controlled. In India, a study using a SMS was performed in 2008, leading to an increase in the practice of BSE from 40.0% to 72.6% after six months [14].

Unlike previous studies, we used a smartphone application to improve BSE practice because this approach has several advantages. Today, people spend significant amounts of time using smartphones throughout the day, and mobile applications can be freely downloaded from the Google Play store. Due to their availability, accessibility, and low cost, smartphone applications are likely to be increasingly used for the improvement of health and disease screening. In addition, smartphones can provide multimedia content, including images, text, and video clips, all of which can help users to improve their health.

The overall frequency of BSE did not increase significantly after smartphone application use. However, subgroup analysis showed that the effectiveness of this technology varies by age group. The practice of BSE increased significantly, but only in females less than 30 years of age. This may be due to differences in smartphone usage since younger people tend to be more accustomed to using applications, such as social networks and mobile messaging services, compared with older participants [15]. It is possible that alternative, less complicated, technological approaches (such as SMS or e-mail alerts) may be more effective in older females. In previous studies about smoking cessation, SMS as a health behavior intervention was used, and the smoking quit rate was significantly increased (Table 3) [21].

However, this study has novel approaches to induce BSE and prevent breast cancer. First, we adopted the optimal timing of intervention based on user's menstrual cycle data. Because breast tissue softens and an abnormal mass can be more easily distinguished from normal breast tissue 7 days after the onset of menses, this user-tailored method could improve the effectiveness of BSE. Actually, during the study, we used repeated reminders to notify users of their optimal BSE date, which significantly increased the proportion of females carrying out BSE at the appropriate time from 2.2% to 33.3% (p < 0.001). However, this is still lower than the results of a previous study carried out in the United States [13]. This suggests that a multimodality method that is more sophisticated than simple notifications may be required to further increase the frequency of BSE. There have been previous attempts to modify health-related behavior using smartphone technology. For example, with human immunodeficiency virus-infected patients, collaborative methods to improve drug adherence, including videos about the effects of the drugs and personalized feedback from the physician, increased the overall adherence to the medication regimen [23]. In a study on weight loss, a sociable robot-based application interacted with the user, and was successful in modifying behavior and achieving weight loss [24]. Our study could therefore be further improved by including additionally mixed interventions, such as physicians' feedback.

Second, we used the social support of family to induce BSE. The prevalence of breast cancer is high in females aged 50-60 years [25]. However, many females in this age group do not know how to accurately perform BSE and live apart from their children. Also, the smartphone penetration rate for older people is increasing. The use of smartphones has sharply increased from 4.6% (2011) to 46.8% (2012) for those in their fifties, and from 9.5% (2011) to 35.9% (2012) for those in their sixties [26]. Therefore, we included a function encouraging participants and their mothers to practice BSE together. Although the application reminded users to call their mothers at the appropriate time so they could practice BSE together, only 6 of the 45 participants (13.3%) actually did BSE with their mothers during the study period. However, we believe that using daughters' recommendation to motivate their mothers could be an effective method to promote BSE in menopausal females. Social support could be an effective intervention in mobile health.

Third, we focused on the possibility of a mobile screening test for breast cancer. Mammography is a screening method for breast cancer in Korea, but dense breast tissue, which could decrease the accuracy of mammogram results is common in Korean women. Therefore, the use of ultrasonography for the detection of breast cancer is used to compensate for the lower accuracy of mammography. Because ultrasonography is not covered by the national health insurance, an additional charge is incurred. On the contrary, BSE improves the accuracy of mammography in breast cancer screening without the burden of increased expenses [27]. During daily practice, a palpable mass is the most common sign used by physicians to identify potential breast tumors. Participants could learn and apply BSE through the smartphone application containing a video clip. Four of the participants (8.9%) found an abnormal mass after BSE, and went to the hospital to have the mass assessed. This suggests that use of the smartphone application could facilitate the early detection of an abnormal breast mass, and potentially cancer.

It must, however, be noted that our study had several limitations. Most of our participants (88.9%) were highly educated and had graduated from university. This is significant, as the practice of BSE is significantly correlated with education [12,28]. Additional studies including participants with a wider range of education levels should therefore be performed. Another limitation was the short study period (2 months) since BSE should be performed regularly over a long period. However, to evaluate the long-term effects of the smartphone application, a central server capable of data collection and analysis may be required. To determine the long-term effect, the researchers need financial support to build a real-time data collection system and legal support regarding privacy to accumulate smartphone user's data. Also, it is necessary to reduce loss to follow-up. Unlike other interventions, the smartphone application could be removed by a user unintentionally through OS upgrade or a change of smartphone. Therefore, regular feedback is required to confirm use of the application.

In conclusion, our findings demonstrate the potential benefit of using a smartphone application to enhancing BSE practice using reminders, a "mother motivation" function, record keeping, and educational content. These results may facilitate the development of more sophisticated mobile screening methods for breast cancer.