Abstract: Background and purpose: Recurrence and metastasis are the key factors affecting the survival prognosis of breast cancer patients. The pathological mechanisms involved in recurrence and metastasis of breast cancer are complex, and biological markers for early monitoring have not been developed clinically. This study aimed to investigate the correlation between polymorphisms of adenosine triphosphate-binding cassette family G2 (ABCG2) gene and recurrence of breast cancer in Xinjiang Uygur Autonomous Region after 2 years of adjuvant chemotherapy, and explore its possibility as a marker of breast cancer recurrence. Methods: We collected the data of 150 patients with recurrence within 2 years following surgery from Dec. 2014 to Dec. 2015 at the Third Clinical Medical College of Xinjiang Medical University. Meanwhile, data of 162 patients without relapse within 2 years were collected as the control. The clinical information was collected, and the polymorphisms at four sites of rs2032582, rs1045642, rs2231137 and rs2231142 were detected. The correlation between the four sites and recurrence of breast cancer within 2 years was compared. Results: There was difference in age, number of lymph node metastasis, estrogen receptor (ER) (+), progesterone receptor (PR) (+) and the histological grading between the two groups. The difference in rs2032582 expression was observed between the two groups, and the expression of rs2032582 GG type mutation in recurrent group was obviously higher than that of other type. The patient with the rs2032582 locus G/T allele was significantly older in the 2-year recurrence group compared with the A allele group (P<0.01), while the A allele group had significantly higher tumor size, number of lymph node metastasis and ER (+) compared with G/T allele group (P<0.05). Conclusion: rs2032582 GG type was associated with breast cancer recurrence in the first two years after surgery. ABCG2 could be a marker gene for early detection of breast cancer recurrence.

Key words: Breast cancer, Adenosine triphosphate-binding cassette family G2, Genetic polymorphism, Drug resistance