Table 2.

Effect of selenomethionine on prostate carcinogenesis and nonneoplastic prostate lesions in 17β-estradiol plus testosterone–treated NBL rats

Group123
Selenomethionine dose (as selenium, mg/kg diet)01.53
Effective no. of animals303030
Mortality (wk after start of hormone treatment)
Mean wk of death ± SD43 ± 6.041 ± 6.244 ± 5.7
Median wk of death (95% confidence interval)42 (40,45)41 (39,44)46 (41,46)
Range (minimum to maximum)28-5322-5532-52
Lesion incidenceNo. (%) of rats with lesion
Adenocarcinoma
    Total cancer incidence29 (97%)28 (93%)29 (97%)
        Periurethral dorsolateral/anterior prostate ducts27 (90)25 (83)27 (90)
        Distal anterior prostate ducts16 (53)19 (63)17 (57)
        Dorsolateral prostate lobe (glandular portion)01 (3)1 (3)
        Anterior prostate lobe (glandular portion)2 (7)01 (3)
        Seminal vesicle (glandular portion)1 adenoma01 carcinoma
    Tumor multiplicity
        One or two carcinomas5 (17)7 (23)8 (27)
        More than two carcinomas24 (80)18 (60)21 (70)
    Carcinoma in situ (but no carcinomas)
        Anterior prostate (glands & ducts)3 (10)02 (7)
        Seminal vesicle (glands & ducts)1 (3)01 (3)
Focal dysplasia in anterior prostate (no. of animals with lesion/evaluable animals)
    Anterior prostate (glands & ducts)16/25 (64)23/26 (88)15/22 (68)
Inflammation & focal dysplasia in lateral prostate
Inflammation (no. of animals with lesion/evaluable animals)
    Total incidence30/30 (100)30/30 (100)30/30 (100)
        Marked inflammation3 (10)3 (10)2 (7)
        Slight, moderate inflammation27 (90)27 (90)28 (93)
Dysplasia associated with inflammation (no. of animals with lesion/evaluable animals)
    Total incidence25/25 (100)26/26 (100)22/22 (100)
        Moderate dysplasia3 (12)07 (32)
        Slight dysplasia22 (88)26 (100)15 (68)
Dysplasia not associated with inflammation (no. of animals with lesion/evaluable animals)
    Total incidence25/25 (100)26/26 (100)22/22 (100)
        Moderate, marked dysplasia25 (100)*24 (92)13 (59)*,
        Slight dysplasia0*2 (8)9 (41) *,

NOTE: Data were tested for significance using the Fisher's exact test and for linear trend with dose using a 2 × 3 χ2 test. Differences were considered statistically significant at P ≤ 0.05 (two-sided for Fisher's exact test). Note that for lesions that can only be assessed micropscopically, the number of evaluable animals (with nonautolytic tissue) was often lower than the effective number of animals.

  • *P = 0.0004.

  • P = 0.0134 for difference between high-dose group and control or low-dose group, respectively (Fisher's exact test).