Table 1.

Tumor incidences and P values for difference between mutant and its wild-type group

C57BL/6J 1Xpa−/−PC57BL/6J 2Xpc−/−P
No. animals (absolute)40312938
All organs
    Tumor-bearing animals30 (75)21 (68)24 (83)23 (61)
Liver
    Hepatocellular tumor0 (0)3 (10)0.00022 (7)5 (13) *
Lung
    Bronchioloalveolar tumor0 (0)2 (6)1 (3)6 (16)0.02
Pituitary
    Pars distalis adenoma20 (50)8 (26) *20 (70)9 (24)0.01
All organs
    Pituitary adenomas excluded18 (45)19 (61)0.00121 (72)23 (61)
  • NOTE: Data are absolute values with percentages in brackets. Statistics: poly-k test (poly-3 test and Peto test generally gave similar significances, although exact P values may differ).

  • * Approaches significance with poly-3 test only (P = 0.08 for Xpc−/− liver and P = 0.054 for Xpa−/− pituitary).

  • Not reaching significance with poly-k test, but P = 0.05 (positive trend) by the Peto test in this case.