In invasive breast carcinomas, negative hOGG1 immunostaining was associated with several factors linked traditionally to poor prognosis: very high Ki-67 expression (P=0.023), grade III differentiation (P=0.01), presence of lymphatic vessel invasion (P=0.036), and absence of oestrogen (P=0.016) and progesterone (P=0.016) receptor expression. This evidence concerns the gene OGG1 and invasive breast carcinoma.