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A Consortium Of Expert Brachytherapists
Publish State-Of-The-Art Results
(November 2007)
Optimal outcomes for seed brachytherapy are importantly
dependent upon the skill and experience of the operator. Dr. Greg
Merrick, Schiffler Canter Center, Wheeling, WV, leading a group of BT
practitioners (including Dr. Kent Waller, Group Health Cooperative,
Seattle, WA) has demonstrated that with scrupulous dosimetry and
meticulous placement of some seeds beyond the physical boundary of the
prostate in Gleason score (GS)7 disease they have been able to
neutralize the adverse consequences of a major Gleason pattern 4. This
pattern is considered more inherently aggressive and likely to
metastasize than pattern 3 and is associated with a greater extent of
extracapsular extension. Dr. Merrick's team treated 530 men, 300 with GS
3 + 4, and 230 with 4 + 3. His report, "Primary Gleason Pattern Does
Not Impact Survival After Permanent Interstitial Brachytherapy for
Gleason Score 7 Cancer", appeared in CANCER July 15, 2007.
The results of their work challenge the notion "that
Gleason score 7 can be stratified into prognostic categories by dominant
histologic grade." This report is important, additionally, as being
illustrative of the excellent outcome that can be achieved by
state-of-the-art technique. Since the management strategies applied ADT
and EBRT differently according to individual patient risk factors, it is
difficult to compare the results with other primary modes of therapy.
An important collateral observation arose from analysis
of the causes of death in the study: "...cardiovascular/pulmonary
disease and second malignancies accounted for 46 of the 57 deaths
(80.7%), with only 5 of the deaths (8.8%) attributable to prostate
cancer (0.9% of all patients) [at a median follow-up of 5.7 years]. This
9.6 fold increase in non-cancer related deaths suggests the need for
counseling prostate cancer patients to optimize healthy life-style
choices. Overall in this study "Patient age, diabetes, and tobacco usage
were the strongest predictor of OS [overall survival, as opposed
to CSS]."
What were the demographics of the 530 men in the study?
The two groups were comparably composed: median age, 67 years; median
pretreatment PSA, 6.8 ng/ml; prostate volume, 33.5 cc; percentage of
positive biopsies, slightly higher in the Gleason 4 + 3 group (50% vs.
36.9%); and the dosimetry was similar with a median D90 of 118.9 Gy.
Pd-103 was used in 93.2% and 6.8% received I-125. The clinical stage was
T1b-T2b in 94.3% of the Gleason 3 + 4 group (n=283) vs 87.4% (n=201);
and was T2c-T3 in 5.7% (n=17) for men with GS 3 + 4 vs 6.1% (n=14) for
GS 4 + 3 men. Patients with PSA values > 10 and/or stage > T2c
received a staging pelvic CT and bone scan. "No patient underwent
seminal vesicle or pathologic lymph node sampling."
What variation of adjuvant treatments were used to
address the differing risk categories among the men? EBRT (45 Gy) was
given (before BT) in 77.7% and applied to a similar extent in both
Gleason groups, with a larger pelvic treatment field given to those
whose risk of lymph node involvement was judged to be more than 10%. ADT
(< 6 months) was given to 23.4% pre-BT to address the suboptimal
geometry of large glands; and 10% (n=53) received prolonged ADT (> 6
months) for poor prognosticators. The overall median duration of ADT was
4 months.
Practitioners treating prostate cancer will recognize
that the population under treatment in this study reflects the current
community demographics of men who present for prostate cancer treatment,
and that the management regimens in this study correspond to accepted
high-grade radiotherapy practice.
The results: "At 10 years, Gleason 3 + 4 versus 4 + 3 did
not predict for CSS (96.7% vs. 93.3%), bPFS (97.0% vs 92.9%5), or OS
(77.0% vs 78%). Clinical stage and radiation dose predicted for CCS; and
clinical stage, pretreatment PSA, and prostate volume predicted for bPFS.
Dr. Merrick would argue that his study gives credence to
aggressive therapy ( EBRT and permanent seeds) in these mostly
intermediate risk patients.
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