Examination of mRNA expression in all 21 cancer types revealed positive correlation between three NR gene clusters, namely 1) NR4A1, NR4A2, NR4A3 (NR class IV), 2) AR, ESR1, ESRRG, NR2E3, NR3C2, PGR, RORC, THRB (NR class I/II/III), and 3) HNF4A, HNF4G, NR0B2, NR1H3, NR1H4, NR1I2, NR5A2, PPARA, PPARG (NR class 0/I/II/V; Fig. 4A). This evidence concerns the gene PGR and cancer.