There were no significant differences in clinical parameters like tumor volume, clinical stage or lymph node status between the two hypoxia groups There was, however, an increased occurrence of hypoxic tumors in the invasive lobular carcinomas (p=0.02), and decreased occurrence of hypoxic tumors in estrogen receptor negative tumors (p=0.04) (Table 1). This evidence concerns the gene ESR1 and invasive lobular breast carcinoma.