We analysed the number of somatic mtRNA variants (grouped variable as 0 variants, 1 variant and >1 variant per tumor, Table 1) and the expression of the entire mitochondrial contig (continuous variable, Table 1) in relation to traditional clinicopathological variables including age at diagnosis (n = 291 cases), tumor size (T-stage) (n = 216 cases), pathological grade (n = 282 cases), estrogen receptor (ER) status (n = 291 cases) and progesterone receptor (PR) status (n = 288 cases). The gene discussed is ESR1; the disease is neoplasm.