Abstract Breast cancer is a malignant and deadly disease for women. The high number deaths causes by breast cancer comes second after cerucal cancer, some of the risk factors of breast cancer are fast food or junk food and the lack of knowledge of the symptoms. The purpose of this study is to analyze the different of knowledge and history consumed fast food junk food between mother breast cancer first stadium and last stadium at RSUD Dr Kanudjoso Djatiwibowo Balikpapan. The method is riset survey with approach restrospective. The respondents consist of 45 people individuals by using accidental sample technique. The data is obtained from questionare. The data analysis univariat, bivariat analysis with statistic test chi square (x2) and multivariat analysis of logistic regression. the result with minimum knowledge are 25 (55.6 %), who consumed fast food are 34 (75.6 %), also there is a correlation between knowledge toward breast cancer at P value = 0.006, there is a correlation between fast food towards breast cancer at P value = 0.04. on the regression test there is meaningful correlation between knowledge towards breast cancer than fast food where the P value = 0.04 and the result of data analysis obtained and fast food P value = 0.264 The conclusion that the dominant factors of breast cancer is knowledge whereas fast food is the effect of the risk.There fore, health professionals, the agencies to give a socialization, giving information about breast health, to consume healthy food for our body as prevention of breast cancer. Keyword :knowledge, fastfood, breastcancer Abstrak Kanker Payudara penyakit yang berbahaya bagi kaum wanita dan mematikan, Tingginya angka kematian kanker payudara pada urutan kedua setelah kanker rahim. Faktor penyebab resiko kanker payudara,makanan cepat saji junk foof dan kurangnya pengetahuan tanda gejala kanker payudara. Tujuan penelitian mengetahui analisis perbedaan pengetahuan dan riwayat konsumsi makanan cepat saji antara Ibu kanker payudara stadium awal dan stadium lanjut di RSUD Dr.Kanudjoso Djatiwibowo Balikpapan. Metode penelitian survey dengan pendekatan restrospective. Responden berjumlah 45 orang dengan tekhnik Accsidental sample. Pengambilan data menggunakan kuesioner. Analisis data univariat, bivariat dengan uji statistik chi square (x2) dan analisis multivariat uji regresi logistik. Hasil penelitian: pengetahuan kurang baik 25 (55.6%), yang suka makanan cepat saji 34 (75.6%), terdapat hubungan pengetahuan terhadap kanker payudara nilai (p value = 0.006), terdapat hubungan makanan cepat saji terhadap kanker payudara nilai (p value = 0.04). Uji regresi terdapat hubungan bermakna pengetahuan terhadap kanker payudara p value = 0.04 daripada makanan cepat saji p value = 0.264. Kesimpulan: faktor dominan berhubungan dengan kejadian kanker payudara adalah pengetahuan sedangkan makanan cepat saji merupakan efek resiko. Harapan: tenaga kesehatan, instansi terkait dapat mensosialisai, memberikan informasi kesehatan tentang payudara, mengkonsumsi makaanan yang sehat tepat untuk tubuh sebagai upaya pencegahan kanker payudara. Kata kunci : pengetahuan, makanan cepat saji, kanker payudara