RESUMO
DNA methylation of polycomb group target (PCGT) genes is an early step in carcinogenesis and could potentially be assayed to determine cancer risk prediction. To assess whether methylation changes in PCGT genes in normal tissue is able to predict the presence of cancer, we studied HOXA gene methylation in normal endometrium from premenopausal ovarian cancer patients and age-matched healthy controls without ovarian cancer. DNA methylation of HOXA9 and HOXA11 genes in normal endometrium was associated with ovarian cancer in an initial test set and this was subsequently confirmed in independent validation sample sets. The overall risk of ovarian cancer was increased 12.3-fold by high HOXA9 methylation for all stages, and 14.8-fold for early stage ovarian cancers, independent of age, phase of the menstrual cycle and histology of the cancer. The results of this proof of principle study demonstrate the potential to detect ovarian cancer via analysis of normal endometrial cells and provide insight into the possible contribution of this novel approach in ovarian cancer risk prediction and prevention.