BACKGROUND. The clinical value of DNA ploidy analysis in prostate carc
inoma has been an issue for investigation for more than 2 decades. In
general, diploid or pseudodiploid tumors are associated with a favorab
le prognosis and aneuploid tumors with an unfavorable prognosis, irres
pective of type of treatment. Turners with DNA values in the tetraploi
d region (around 4c) present a diagnostic problem. Such DNA distributi
ons may clearly represent aneuploid tumors with an unfavorable prognos
is. However, a 4c distribution may conversely represent a tetraploid t
umor (possibly a polyploid variant of the diploid tumor) with a favora
ble prognosis. Previous data from our laboratory indicate the existenc
e of such a tetraploid subgroup. The goal of the current study was to
investigate the diagnostic problem of 4c tumors in greater detail. MET
HODS. Ploidy classification of cytologic smears by image cytometry was
performed in a retrospective study of 334 patients with hormonally tr
eated prostate carcinoma. Follow-up time was 30 years or until death.
RESULTS. Three ploidy types were defined: near-diploid (D type), near-
tetraploid (T type), and highly aneuploid (A type). Tumors with a moda
l value within the tetraploid region were found in 27% (92 cases) of t
he total material. Of these, 9% were defined as T type and 18% as A ty
pe. Overall, 37% of the tumors were classified as D type, 9% as T type
, and 54% as A type. Of the A type tumors, one-third had modal DNA val
ues in the tetraploid (4c) region. Multivariate analysis showed a stat
istically significant difference between A type tumors and D and T typ
e, but not between D type and T type. Both D and T type tumors progres
sed slowly and killed the patients 5 to 30 years after diagnosis, wher
eas A type tumors progressed rapidly and killed the patients within 6
years of diagnosis. CONCLUSIONS. By image cytometry, prostate carcinom
a can be divided into three ploidy types: D, T, and A type. Biological
ly, however, the tumors fall into only two groups: low grade malignant
, pseudodiploid tumors of D or T type, and high grade malignant, highl
y aneuploid tumors of A type. (C) 1996 American Cancer Society.