Eradicating cancer is one of the serious challenges facing global health in the modern era. In 2020, based on data from the Globocan Project¹, breast cancer was one of the cancers with the largest number of new cases (11.7% of all new cancer cases) and one of the cancers with the highest number of deaths (6.9% of all cancer deaths). The Globocan Project² also showed that the incidence of new cases of breast cancer in Indonesia accounts for the largest proportion (16.6%) compared to the number of new cases of other cancers. The proportion of new cases of breast cancer from the total number of new cases in women in Indonesia is even greater, reaching 30.8%.²

The latest developments in multidisciplinary medical science and technology allow for an increase in the chances of successful therapy in breast cancer patients, although it requires a more comprehensive therapeutic approach.³ However, a preventive approach by suppressing risk factors remains one of the keys to success in controlling breast cancer.⁴ Another important factor in controlling this disease is detecting breast cancer at the earliest possible stage in order to increase the chances of successful therapy and reduce the risk of suffering and death.^3,4

There are several methods used for breast cancer screening, including mammography and various other imaging techniques, clinical breast examination (CBE), and breast self-examination (BSE).³ Until now, mammography has been the definitive method used for early detection because of its effectiveness and contribution to reducing breast cancer mortality rates.⁵ However, this method requires the support of adequate health facilities, infrastructure, and resources.⁶ In developed countries, the use of imaging methods such as mammography may not face major obstacles, but in developing countries, limited health facilities and resources are a very serious challenge. Therefore, in developing countries, CBE and BSE, which are more resource-efficient, may need to be considered for campaigning so that they can be implemented more widely in the community. These practices are expected to help increase the chances of successfully detecting breast cancer at the earliest possible stage.⁷

In Indonesia, the CBE screening program is implemented in primary health care facilities by general practitioners and trained midwives.⁸ However, a study by Wahidin et al.⁹ showed that the coverage of CBE is still low, reaching only 9.8% of the target population of women aged 30 to 50 years. The study also showed that although this program is implemented in all provinces, only about 51% of primary health centers have implemented it. There appear to be serious obstacles to expanding the coverage of this program evenly across regions due to the high disparity in resources between provinces and the limited capacity of primary health care facilities and finances in the regions.⁹ Therefore, increasing the coverage of BSE participation can be a rational choice in improving the success of screening. BSE also seems more likely to be practiced widely and routinely in women because it is practical, can be done at home, is free and non-invasive, and seems to be preferred by women.^10,11 Although it is not a substitute for imaging methods such as mammography,³ screening using BSE is also expected to initiate women to carry out further breast examinations in healthcare facilities and form habits and high awareness of their respective breast health.⁶

Thus, identifying factors associated with BSE practices in female populations in developing countries becomes even more crucial.³ Initially, identification may need to be prioritized in a more specific population.⁶ Prioritizing female health science students may be appropriate, given their greater exposure to health information and knowledge, as well as their potential for greater influence on the general female population in the future. The results of various studies seem to indicate a tendency for diverse factors to be associated with both general breast cancer screening^3,12 and BSE participation rates among female students in developing countries.^13–15

Two factors seem crucial to investigate in their association with BSE participation. First, knowledge about breast cancer, specifically about BSE. The association between knowledge about BSE and BSE practice has been demonstrated by several studies,^10,14,16 but it seems that the relationship between knowledge about breast cancer risk factors and BSE practice has not been widely demonstrated. The second factor is fear of breast cancer, which seems to be prevalent in the female population and has been widely studied.^17–21 The hypothesis that fear factors are related to breast cancer screening participation¹⁷ seems quite reasonable, although it has not been proven by several previous studies;^19,21,22 thus, gathering evidence in different populations seems necessary.

Although there have been studies on BSE in Indonesia,^23–25 domestic studies that quantitatively describe breast cancer fear in the local population have not been conducted. Furthermore, domestic studies that examine the interaction between breast cancer knowledge and fear in the context of their association with BSE participation—to our knowledge—appear to be lacking. Therefore, to address these research gaps, this study aims to examine the relationship between a) breast cancer knowledge, b) breast cancer fear, and c) BSE practice among female undergraduate students.

This study uses a cross-sectional design because this design is relatively easy to carry out, can collect many measurement results of research variables at the same time quickly, so that it is suitable for use when resources are very limited, and is the main choice for determining the prevalence and relationships between many variables.²⁶ Data were collected in September 2023. Participants were female students of the Health Polytechnic of the Ministry of Health, Jakarta III, located in Bekasi City, West Java, Indonesia. This campus is the only state campus majoring in health in Bekasi City, making it suitable to be chosen as a research location in accordance with the background that we have mentioned previously, to focus on the population of female health students as our research subjects. The minimum sample size was estimated based on the formula proposed by Lemeshow et al.²⁷ for proportion: where Z²_1-α/2 is the Z statistic (1.96 at a 95% confidence interval), and “P” is the estimated proportion of female students who practice BSE. In this study, “P” was 0.499, referring to the results of a meta-analysis of studies from 2017–2022 in Indonesia,²³ while “d” is the absolute precision, which we set at 10%. After calculating with a laptop calculator, we got a minimum sample size (n) of 97 participants.

For sample selection, we used the convenience sampling method. Data were collected from participants using an online questionnaire (Google Form) in Indonesian until the minimum sample size was exceeded. We distributed the questionnaire link to prospective participants through face-to-face meetings in class and also distributed it via the class WhatsApp group. At the beginning of the questionnaire, there was a written explanation of the study. Only prospective participants who voluntarily gave online consent to participate in this study could continue to fill out the questionnaire. We made arrangements so that each participant could only fill out the questionnaire once. We ensured that the participants who filled out the questionnaire were female students at the campus by verifying the participants' identities. In addition, we also took steps to protect data confidentiality by providing passwords for both the data file and the laptop used to store and process data. After verifying the participant's identity, in further data processing and analysis, we replaced it with a number code.

Overall, of the 320 participants who filled out the questionnaire for this study, 59 participants were excluded from further data analysis because they were 30 years old and above, the campus location was outside Bekasi City, or the profile data was incomplete. Thus, the number of participants in this study was 261 female undergraduate students.

Digital-based information media seems to be the main choice of participants to get information about breast cancer. It can be seen that social media (28.7%), physicians (28.3%), and websites (22.6%) were chosen by far more participants than conventional media such as television (0.4%). More complete characteristics of the participants in this study are shown in Table 1. The proportion of participants who had a good knowledge of BSE was slightly larger than those who had a poor knowledge. The majority of participants had a poor knowledge of breast cancer risk factors. In addition, the majority of participants had high CBCFS scores (Table 2).

Table 3 shows the description of BSE practices among participants. Although most participants admitted to having or being used to practicing BSE, only 30% of participants admitted to practicing it regularly every week/month. It was also seen that there were various reasons for participants to practice or never practice BSE, but there was no reason with a dominant proportion. It appears that although fear of breast cancer was the reason with the largest proportion, the figure did not reach half, only 39.9 percent, indicating that there were other reasons that encouraged participants to practice BSE. Most participants who had never done BSE admitted to having plans to seek more in-depth information and practice BSE. As seen in Table 4, seven variables based on bivariate tests have a P-value ≤0.25, namely breast cancer fear, knowledge of BSE, knowledge of breast cancer risk factors, age, work, father's education, and history of other cancers in the family.

The 7 variables were then included in the multivariate logistic regression test with the backward likelihood ratio method to determine the determinant factors of BSE practices. In the final model (step 5), the Cox and Snell R² value was 0.100, the Nagelkerke R² value was 0.139, and the Hosmer-Lemeshow test Significance was 0.862.

In Table 5, it can be seen that in the final model, 2 variables were statistically significant (P-value <0.05) as determinants of BSE: knowledge of BSE and age.

Most participants in our study chose social media and websites as sources for obtaining information about breast cancer. This is understandable considering that among young people—especially Millennials (those born between 1981 and 1996) and Generation Z (those born between 1997 and 2012)⁴⁶— Internet use is relatively high. The 2024 Indonesian Internet Penetration Survey⁴⁷ results prove this: 93.17% of Millennials and 87.02% of Generation Z in Indonesia use the internet. The 2024 IIPS appears to be quite strong in representing the internet behavior of the Indonesian people because it is a face-to-face survey of 8,720 respondents aged 13 years and over who are spread proportionally across all provinces and selected using multistage random sampling.⁴⁷ These findings seem to support the potential of digital media or internet-based mobile applications as health promotion media that will be more effective in increasing awareness among young women in breast cancer prevention.^48,49 In addition, our study also shows that physicians are still one of the main sources of information about breast cancer for female undergraduate students—chosen from almost throughout the participants. Apparently, the credibility of physicians as a source of health information is still relatively high from the perspective of female undergraduate students.

Although the majority of participants admitted to having practiced BSE, of that number, those who practiced it regularly every week or every month did not reach half. In addition, of the female students who practiced BSE, most did it not on the days recommended by the guidelines^31,32 (1 to 3 days after menstruation ends) but on other days at random. This seems to indicate the need for more effective education so that female students can practice BSE correctly according to the guidelines.

Based on our study, the proportion of participants who had good knowledge about BSE was 51.3 percent, not much different from the proportion of participants who had good knowledge (49.9%) in a study¹⁰ in Ethiopia. Meanwhile, the majority (70.9%) of participants in our study had poor knowledge about breast cancer risk factors. A previous study in Bandung, Indonesia⁵⁰ also reported that most female high school students and undergraduate students (53.1%) had poor knowledge about breast cancer risks.

The main findings of our study showed that the level of BSE knowledge was a statistically significant determinant of BSE practices. Female undergraduate students with good knowledge of BSE had an odds ratio of 2.46 times to practice BSE compared to female undergraduate students with poor knowledge of BSE. This result confirms previous studies.^10,14,16 Our study also showed that having good knowledge of breast cancer risk factors was not a determining factor for female undergraduate students to practice BSE, confirming the results of a study by Al-Ismaili et al.⁵¹ in Oman. Knowledge of the various conditions that increase the risk of breast cancer alone may not be enough to motivate a woman to do BSE, but there needs to be sufficient knowledge on how to practice it. That most participants who practiced BSE admitted to not doing it regularly and at the wrong time seems to be due to their poor knowledge of BSE practices. Thus, it seems reasonable that more focused education is needed to improve understanding and practical steps of BSE.

The majority of our participants tended to have high levels of fear of breast cancer. A previous study¹⁸ among women aged 17 to 35 years in Spain, also reported similar findings: more than half of the participants (59.73 percent) had a high fear of breast cancer. A study¹⁹ in Nigeria also reported that the majority (68%) of participants (women aged 40–64 years) had a high fear of breast cancer. An interesting finding was that fear of breast cancer, although recognized by almost 40% of our participants as the main reason for performing BSE, was not statistically significant enough as a determining factor for practicing BSE. This result strengthens the findings of previous studies.^19,21,22 The findings of a qualitative study in Turkey¹² may help explain this: fear of breast cancer and anxiety about the possibility of undergoing further diagnostic processes are factors that make many women reluctant to undergo breast cancer screening, although for some women, it is a motivation to participate in screening.

In addition, our study also showed that age is a determining factor for performing BSE. Participants aged 20–29 years were more likely to practice BSE compared to those aged 17–19 years. This result is in line with the results of another study¹⁹, which showed that older women were more likely to participate in mammogram screening. Older women may tend to have more exposure to health information than younger women. In addition, there also appears to be a perception among women that as they age, they are at greater risk of developing various diseases.¹³

This study also contributes to the identification of factors associated with BSE participation. However, we acknowledge the limitations of this study. Our study was only able to explain 13.9% (Nagelkerke R² of 0.139) of the possible factors associated with BSE participation, indicating that many factors have not been identified by our study. In addition, the convenience sampling method used in this study may lead to potential selection bias.²⁶ We must acknowledge that our study may not be representative of female students in general, so these results may not be directly generalizable to a wider population.

Finally, we can conclude several things. First, although the participation rate of BSE among female undergraduate students in our study appeared to be quite high, the time and frequency of the practice generally still need to be improved. In line with this, the government and organizations in the field of breast cancer control are expected to conduct massive health campaigns among female undergraduate students. Health campaigns that include the dissemination of health information messages, video-based tutorials, and Q&A sessions can be conducted primarily by doctors through social media or mobile applications, which appear to be more appropriate for young women and may be more effective.^48,49 Second, good knowledge of BSE has been proven to be a determining variable in BSE participation. Thus, campaign materials that focus on knowledge of how to perform BSE correctly are expected to increase not only the level of participation but also the quality of BSE practice. Third, other determinants of BSE participation still need to be identified in further studies. Further studies are recommended to involve more variables, larger sample sizes, and wider geographical distributions. Mixed methods studies may be needed to reveal more about the phenomenon of breast cancer fear and its interaction with breast cancer screening.

This study protocol has been reviewed and ethically approved by the Health Study Ethics Commission, Faculty of Public Health, Universitas Muhammadiyah Jakarta (No. 10.229.B/KEPK-FKMUMJ/VII/2023).

Data related to this study are presented in the article.