Sometimes when patients originally present with very high
PSA levels, a negative bone scan, and CT, they are put on permanent hormone
therapy because the doctor just assumes it is micrometastatic. A closer look at
the data demonstrates that an attempt at curative radiation may improve
outcomes.
Lawrence et al. screened the 2004-2008 SEER database, and found 75,539 patients
diagnosed with non-metastatic prostate cancer, and excluded those treated with
surgery or brachytherapy. The patients had a median age of 70 years. Their
findings based on a median of 60 months of follow up were:
- · Use of RT was associated with a reduction in prostate cancer mortality of 59%.
- · 4-yr prostate cancer survival was 94% in those who had RT vs. 77% in matched patients who had no local therapy.
- · The benefit held even for those with PSA≥75 ng/ml
Three important caveats:
(1) This
is a retrospective study and is subject to selection bias. This means that
those who received no local therapy may have done so for reasons not readily
apparent in the available records. Although the authors made an attempt to
account for age, grade, PSA level, stage and perhaps other variables, there may
have been signs of greater progression that the doctor was aware of.
(2) The
PSA values recorded in the SEER database have recently been called into
question. Interested readers may read more about it here.
In fact, the National Cancer Institute has withdrawn PSA data from the current
files. This analysis was evidently performed before that withdrawal on April
29, 2015. This does not affect the survival data.
(3) A median of 60 months of follow up is
not long enough to determine whether survival benefits are sustained in the
long run. Neither the radiation-treated cohort nor the non-treated cohort
reached median survival during the time period of observation so far available.
Given those caveats, we can only conclude that there may
be something to this, but that can only be determined by a clinical trial where
patients with extremely high PSA levels are randomized to radiation therapy or
hormone therapy only, and they are tracked for ten years or more. The study does
suggest
that PSA alone is not a good risk
factor on which to base the decision about whether to pursue curative therapy.