Table 3

Incidence of lung tumours in the left lung following treatment of A/J mice with NNK or PBS

Duration of treatment (weeks)TreatmentNo of miceNo (%) mice with tumourTotal number of tumours (left lung)p Value
26NNK71 (14.3%)10.317
30NNK93 (33.3%)30.065
34NNK106 (60.0%)90.005
38NNK85 (62.5%)50.009
  • Animals were treated with NNK (100 mg/kg/day) or PBS and killed at 4-week intervals starting weeks after treatment. The number of lung tumours in the left lung was evaluated by H&E staining as described in and the Methods section.

  • NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone; PBS, phosphate buffered saline.