MedWire News: A novel single nucleotide polymorphism (SNP) in the cyclooxygenase-2 (COX-2) gene PTGS2 is associated with the risk of breast cancer, Chinese study shows.
Overexpresion of COX-2 has been reported in breast cancer, and indeed SNPs in PTGS2 have been linked to increased risk of other tumor types. The aim of this study, published in the journal Clinical Oncology, was to identify new mutations and polymorphisms in the COX-2 gene and determine any possible correlation with breast cancer risk.
Using polymerase chain reaction and single-strand conformation polymorphism analysis, Ren Guo-Sheng (First Affiliated Hospital of Chongqing Medical University, China) and colleagues identified a new SNP in PTGS2, in which cytosine is replaced by guanine at nucleotide 169 in exon 2 (169C–>G).
To investigate the role of this SNP in breast cancer, 310 consecutive Chinese Han women with breast cancer were inlcuded in this population-based study between January 2006 and July 2007. Each patient was age-matched with a healthy woman as control.
The homozygous GG variant of PTGS2 was more commonly found in patients (15.2%) than controls (9.4%; odds ratio (OR) 1.76, 95% confidence interval (CI) 1.20–3.05, p=0.03). There was no difference in the heterozygous CG variant between the two groups (OR 0.97, 95% CI 0.84–1.43), thus it appears that any effect on breast cancer risk is recessive.
No association was found between PTGS2 variant and tumor grade or size, lymph node metastases, age at diagnosis, or progesterone receptor status. However, estrogen receptor positivity was less frequent in patients with the GG variant.
The authors conclude that “the 169C–>G polymorphism in exon 2 of the COX-2 gene is associated with the risk of breast cancer and may be a genetic marker for breast cancer”.
They suggest that the role of COX-2 inhibitors in the prevention and treatment of breast cancer may be of potential interest.