Worldwide, there were around 2.1 million breast cancer cases diagnosed in 2018. There was nearly 1 of 4 cancer cases among women with an incidence of 38,1 per 100.000 and mortality of 14,1 per 100.000. This study was aimed to determine whether there was a change in response score of systemic inflammation by using peripheral blood neutrophil level in female patients with advanced stage of breast cancer before and after treatment. This was an interventional analytical study with a cross sectional design, conducted at Prof. Dr. R. D. Kandou Hospital Manado. The results showed that there were 43 patients in the period of May 2018 to August 2018. The youngest age was 34 years and the oldest age was 70 years with a mean of 52.16 years (SD±10.002). The most frequent stage was III B (58.1%), followed by IIIC (25.6%), IIIA (11.6%), and IV (4.7%). Before treatment, the highest level of neutrophil was 55%, the lowest level was 12%, with a mean of 27.84% (SD±10.005). After treatment, the highest level of neutrophil was 45%, the lowest level was 11%, with a mean of 22.7% (SD±6.635). The paired-t test showed a very significant difference in peripheral blood neutrophil level between before and after treatment (P<0.001). Conclusion: There was a significant decrease of peripheral blood neutrophil level in breast cancer patients after treatment.Keywords: plasma neutrophil, advanced stage of breast cancerAbstrak: Di seluruh dunia, terdapat sekitar 2,1 juta kasus kanker payudara wanita yang didiagnosis pada tahun 2018, serta terhitung hampir 1 dari 4 kasus kanker di kalangan wanita dengan insidensi 38,1 per 100.000 dan kematian sebanyak 14,1 per 100.000. Penelitian ini bertujuan untuk untuk menilai adanya perubahan skor respons peradangan sistemik dengan menggunakan kadar neutrofil darah tepi pada pasien kanker payudara stadium lanjut sebelum dan setelah terapi. Jenis penelitian ialah intervensional analitik dengan desain potong lintang, yang dilakukan di RSUP Prof. Dr. R. D. Kandou Manado. Hasil penelitian mendapatkan 43 pasien sejak Mei 2018 s/d Agustus 2018. Usia termuda 34 tahun dan usia tertua 70 tahun dengan rerata usia 52,16 tahun (SD±10,002). Stadium terbanyak ialah stadium IIIB (58,1%), diikuti stadium IIIC (25,6%), stadium IIIA (11,6%), dan stadium IV (4,7%). Sebelum dilakukan tindakan didapatkan kadar neutrofil tertinggi 55%, kadar terendah 12%, dan rerata 27,84% (SD±10,005). Setelah dilakukan tindakan didapatkan kadar neutrofil tertinggi 45%, terendah 11%, dan rerata 22,7% (SD±6,635). Hasil uji t berpasangan mendapatkan perbedaan yang sangat bermakna dari kadar neutrofil sebelum dan sesudah terapi (P<0,001). Simpulan: Terdapat penurunan bermakna dari kadar neutrofil darah tepi pada pasien kanker payudara setelah dilakukan tindakan.Kata kunci: neutrofil darah tepi, kanker payudara stadium lanjut