| Prostate Update |
| August 2000 Vol.
5 No. 1 |
HIGHLIGHTS OF THE 2000 CUA
PROSTATE CANCER
Many excellent papers on prostate cancer were presented
at this year Canadian Urological Association meeting in Kelowna. Interestingly,
the focus of the majority of these presentations was directed to the improvement
of existing therapeutic modalities or the development of new treatment strategies.
First, Drs Chin and Donnelly reported their experience with cryotherapy. Dr Chin
reported on 126 patients treated for locally recurrent prostate cancer following
radiation therapy with a median follow up of 30 months. Using 3D ultrasound for
planning and treatment, a clinical and/or biochemical failure was observed in
only 22.2% of the patients. In addition, they identified PSA > 5.0 ng/ml, Prostate
volume > 40 gm, stage >T3a and Gleason score >7 as predictive factors
for treatment failure. Dr Donnelly reported their results using cryotherapy as
first line of treatment in 76 patients with localized prostate cancer. Interestingly,
both investigators reported an acceptable morbidity associated with the use of
cryotherapy. Dr Donnelly results demonstrated a PSA failure free at 3 and 4 years
of 78% and 74% respectively.
Two presentations reviewed results of radiation therapy trials. First, Catton
et al demonstrated the feasibility of dose escalation to 75.6Gy using 3D conformal
radiotherapy. Their results did not suggest any increased toxicity using this
treatment strategy. Although their follow up was relatively short, the PSA nadir
observed in their patients seems to predict a favorable outcome using this approach.
Warde et al reported their results on 415 patients randomized to either radiation
therapy alone or associated with 3 years of adjuvant androgen ablation. Their
results confirmed Bolla’s data with an increased overall survival from 62%
to 78% in favor of the combined modality treatment. In addition, the disease specific
survival was also improved from 40 to 75 %.
La Bianca et al from Vancouver reported on 156 men who received 8 months of neoadjuvant
therapy prior to radical prostatectomy. Their results reinforced the presence
of a low rate of positive margins with prolong androgen ablation. Furthermore,
they demonstrated a risk of biochemical failure of 12.2% at a mean postoperative
follow up of 54 months.
Trachtenberg et al reported their progress using microwave thermal therapy for
locally recurrent or persistent prostate cancer following radiation therapy. According
to the authors, this novel treatment strategy has limited morbidity compared to
the use of cryotherapy. In addition promising results were demonstrated as 12
of the 19 patients treated had negative prostate biopsy at 6 months.
Excellent basic research presentations were also given during the CUA meeting.
Again, the focus of many of these presentations was on the development of novel
therapeutic approach. Siemens reported on the use of immunotherapy with adenovirus/PSA
vaccination associated with intratumoral cytokine gene transfer. This group observed
the generation of an important anti-tumor activity, mediated primarily by CD8+
T cells in treated patients.
Kiyama et al demonstrated the importance of anti-apoptotic genes such as Bcl-2,
Bcl-xL and TRPM-2. Furthermore, they demonstrated the potential benefit of anti-sense
therapy against these genes. In fact, anti-sense therapy directed against Bcl-2
and Bcl-xL was shown to delay the emergence of androgen insensitive tumors. In
addition, this approach was found to be synergistic with the use of chemotherapeutic
drug such as Taxol. This group also clearly demonstrated the important role played
by TRPM-2. In fact, they demonstrated that TRPM-2 overexpression confers resistance
to cytotoxic chemotherapy and may also mediate resistance to radiation therapy.
Their results suggest a potential role for antisense therapy directed against
TRPM-2 in the treatment of prostate cancer.
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Canadian Prostate Health Council