Dietary aspirin decreases the stage of ovarian cancer in the hen. 
We aimed to determine the effects of dietary aspirin treatment on ovarian cancer incidence and progression in the hen as a model for the human disease.  Hens were fed a standard layer diet (control) or the same diet containing 0.1% aspirin for 1 year.  Liver prostaglandin E(2) (PGE(2)) was measured using an enzyme immunoassay.  Incidence and stage of ovarian cancer were determined through necropsy and immunohistochemical analysis of ovarian sections for each hen.  Aspirin treatment decreased liver PGE(2) in treated hens as compared to control hens.  Treatment with aspirin did not decrease ovarian cancer incidence.  Significantly more control hens developed late stage ovarian cancer than early stage, while the same was not true for aspirin-treated hens.  Hens that developed ovarian cancer, even early ovarian cancer, produced significantly fewer eggs in the year prior to diagnosis than hens without ovarian cancer.  Aspirin treatment may inhibit the progression of ovarian cancer in the hen and egg production may be used to identify hens with early stages of the disease.