1496
HUMAN GLANDULAR KALLIKREIN 2
CONCLUSIONS
distinguished from stages pT3a or greater, the distinction
between stages pT2a versus pT2b and pT3a versus pT3b
disease did not demonstrate a statistically significant differ-
ence. However, the fact that 7 patients had nondetectable
hK2 in the stage pT2a/b group strongly limits their evalua-
tion. A more sensitive hK2 assay may provide better analysis
but currently we cannot answer this question. A more obvi-
ous distinction occurred in pathological stages 3a/b to 4a and
lymph node positive disease. However, it would be premature
to speculate on that finding due to our small number of
patients. We are aware that the inclusion of stage pT4 and
lymph node positive cancer may bias the mean and median of
nonorgan confined cases (tables 3 and 4). It is important to
stress that disease in these patients was also judged to be
clinically localized and, thus, they were candidates for radi-
cal prostatectomy. Surgery was discontinued in patients with
positive lymph nodes. The fact that the perioperative and
postoperative evaluation provided information that cancer
was far more advanced than clinically expected does not limit
the application of hK2 determination for biochemical staging
purposes
The calculation of sensitivity and specificity showed that in
the most important aspect (prediction of stage pT2a/b disease
at 95% sensitivity) hK2 was significantly better than PSA
only and the algorithm combining hK2 with PSA. Calculating
the odds and crude odds ratios by multivariate logistic re-
gression analysis revealed that only the crude odds ratio
indicated a significant advantage for hK2 compared with free
and total PSA. The standard odds ratio only demonstrated a
nonsignificant advantage for hK2. However, this calculation
has limitations because our number of samples was rela-
tively small. In fact, the minimal number of values needed for
multivariate logistic regression is 30, which is exactly the
number of nonorgan confined cancer cases in our study. De-
spite these results the crude odds ratio showed that hK2
performed better since even small changes in the hK2 con-
centrations (increase by 0.2 ng./ml.) strongly elevated the
risk of capsular penetration.
hK2 only or the algorithm, hK2 ϫ (total PSA/free PSA)
improves the preoperative evaluation of patients who un-
dergo radical prostatectomy due to superior separation of
organ and nonorgan confined cancer compared with that of
total and free PSA, and percent free PSA. Thus, the inclusion
of hK2 in the preoperative biochemical evaluation of prostate
cancer may provide a substantial improvement in the selec-
tion criteria of patients with prostate cancer, particularly
with respect to electing nerve sparing radical prostatectomy.
Further evaluation of hK2 is necessary. However, our results
indicate the potential for hK2 to be a promising tumor
marker, perhaps equal to PSA, for adenocarcinoma of the
prostate.
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