Background: P-glycoprotein expression in tissues acts on pharmacokinetics and pharmacodynamics
of drugs. In this context, the C1236T (rs1128503) variant in ATP binding cassette subfamily
B member 1 (ABCB1) gene has been linked to inter-individual responses to many drugs.
Objective: Our study evaluated the association between clinical and laboratory markers of breast cancer
severity, including the recurrence, and C1236T variant in ABCB1 gene.
Method: A total of 138 breast cancer patients were enrolled in our study. The rs1128503 screening
was done by allele-specific polymerase chain reaction. The following data were registered: selfdeclared
ethnicity, body mass index, diabetes mellitus, systemic hypertension, age at menarche, age at
menopause, lactation, use of oral contraceptive, use of hormone replacement therapy, neoadjuvant
chemotherapy, hormonal therapy after surgery, smoking, radiotherapy, estrogen and progesterone receptor
expression, and breast cancer characteristics (recurrence, histological type, histological grade,
nuclear grade, TNM staging and clinical stage). Statistical analysis was performed using the Statistical
Package for Social Sciences software version 21.0 through the χ2 test, Fisher's exact test and
Kruskal-Wallis test. α=0.05 was adopted.
Results: The rs1128503*CC genotype and rs1128502*C allele were associated with breast cancer recurrence
with an OR=2.256 (95%CI=1.054 to 4.829) and OR=2.112 (95%CI=1.18 to 3.781), respectively.
Also, after the correction by multiple tests, only the association between the rs1128502*C allele
and recurrence was kept with a p-value<0.05.
Conclusion: Our data showed that the rs1128503 variant in ABCB1 gene can contribute to breast cancer