Correlates of Distant Metastasis and Death in Prostate Cancer Patients Treated with Radiotherapy

Reviewer: Ryan Smith, MD
OncoLink
Last Modified: October 6, 2002

Presenter: Pollack, Alan
Presenter's Affiliation: Fox Chase Cancer Center
Type of Session: Scientific

Background

Prostate cancer is a slow growing disease that requires a long follow-up to determine data on survival. Due to this phenomenon, many patients die of intercurrent disease unrelated to prostate cancer. Therefore, other endpoints are used, including bDFS (biochemical disease free survival) as determined by PSA to track outcome of patients treated for prostate cancer. However, though biochemical failure (BF) has been shown to be a strong correlate of the development of distant metastases (DM), the relationship of BF to death is not established. This study reports on patients with BF and its relationship to DM, case specific death (CSD), and death.

Materials and Methods

This is a study of 942 patients treated with XRT +/- short term androgen depletion (STAD), of which 13% of the patients received. No patient received more than 3 months of hormonal therapy.
Patients had T1-3 prostate cancer, with 12% with T3 disease
Median pre-treatment PSA value was 9.9
27% of the patients had Gleason Score (GS) 7-10 disease
Median dose of radiation was 72 Gy
Endpoints were development of DM, CSD, and death
A subset of those patients with BF were also studied, analyzing them for correlation with the development of DM, CSD, and death
Median FU was 73 months

Results

316 patients (34%) had BF, with 7% with DM and 24% dying during the study period
OS was 92% in those patients without BF and 84% in those patients with BF
Factors related to the development of DM and death were T3/4 disease, BF, lower XRT doses, and higher nadir PSA, and higher GS
In the BF group, BF was strongly correlated with the development of DM. BF was less correlated with CSD, and not correlated with death.
In those with BF, longer PSA doubling time was inversely related to the development of DM.
In those with BF, the prior use of adjuvant STAD was inversely correlated with the development of DMs

Author's Conclusions

As expected, DM were correlated with BF.
Data is supportive of a relationship between CSD and BF
There was no correlation between BF and death
In those with BF, PSA doubling time is important, as is the use of STAD, as it seems that this use delays the development of DM
Longer follow up is needed to confirm these results.

Clinical/Scientific Implications

As expected, BF correlated with the development of DM, even though BF could reflect local failure only. Though there is less of a correlate between BF and CSD, there is a relationship. There is not a relationship between BF and death, likely because the majority of patients with prostate cancer will die of diseases other than prostate cancer. However, this does not mean that PSA failure as an endpoint should not be used. It does correlate with outcome, just not overall survival. It is obviously not a perfect endpoint, as few "artificial" endpoints are, but with the above correlations, it can still be used as a way to compare different populations and the overall outcomes of these populations. The fact that STAD seemed to decrease the rate of DM after BF indicates that adjuvant hormones may ultimately impact survival by reducing the rate of disease progression after BF is noted.

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