[PSA doubling time in prostate cancer relapsed after endocrine therapy]

The PSA level of prostate cancer patients generally declines after endocrine therapy, but elevates when the cancer relapses in most cases. However, the rate of elevation differs with the case. We investigated the PSA doubling time (PSA-DT) of the prostate cancer patients whose PSA declined after endocrine therapy and later re-elevated, and investigated the relationship with other parameters.

We investigated 55 prostate cancer patients who underwent endocrine therapy between 1991 and 1998. Their PSA re-elevated continuously after their PSA fell below 10 ng/ml after the endocrine therapy as the first line treatment. First, the correlation coefficients with time and PSA were calculated in order to decide whether their PSA elevation was exponential or linear. PSA-DT was calculated thereafter, and compared with the clinical stage, pathological differentiation, clinical relapse style, time from the beginning of the therapy to PSA relapse, pre-treatment PSA value, and prognosis. The relationship between PSA-DT and each clinical parameter was tested using the Kruskal-Wallis test. Differences in survival rates and PSA-DT were calculated using the log-rank test.

PSA elevated exponentially after cancer relapsed. PSA-DT in all cases ranged from 0.5 to 26.3 months, with an average of 4.4 +/- 4.8 (S.D.) months and the median was 2.5 months. PSA-DT was significantly (p < 0.01) short when the pre-treatment clinical stage was high, the time from the beginning of the therapy to PSA relapse was short, or the pre-treatment PSA value was high. PSA-DT tended to be short when the pre-treatment pathological differentiation was low, but not significantly. PSA-DT tended to be short when the cancer relapsed as distant metastasis rather than regional relapse, but not significantly. Prognosis from the initial treatment and PSA relapse was significantly poor when the PSA-DT was short.

PSA elevated exponentially in the relapsed prostate cancer patients after the endocrine therapy. PSA-DT was distributed in a very wide range, and this value was considered to reflect the malignant potential and prognosis of the cancer. PSA-DT may be useful for determining the strategy after relapse.