Current Treatment Options
Early detection of prostate cancer leaves several treatment
options.
Approximately 50% of diagnosed men elect to have surgery with or
without external beam radiation, and the other half elect to have
seed therapy (brachytherapy) with or without external beam
radiation. Approximately 30% of patients fail primary therapy over
a 5-year period and subsequently receive hormone therapy. Hormone
therapy slows the tumor growth by stopping or blocking testosterone
from entering the cancer cells. Prostate cancer cells are typically
dependent on testosterone or other androgens as growth factors.
Hormonal therapy can be effective for long periods of time,
reducing tumor progression and relieving pain as well as other
symptoms. Eventually, however, all men will progress into later
stage disease as the cancer becomes castration-resistant.
Rising PSA blood levels while on hormonal therapy identifies the
next stage of prostate cancer called castration-resistant prostate
cancer. Some men move into this stage with identified metastatic
lesions either in the bone or in lymph nodes, while the majority of
men have only rising PSA blood values.
Chemotherapy is mainly used to treat advanced prostate cancer
that is no longer being controlled by hormonal therapy. It is used
in an attempt to shrink and control the cancer and relieve symptoms
with the aim of prolonging life. Chemotherapy for the treatment of
metastatic prostate cancer is very limited; only one product, with
a survival benefit of ~ 2-3 months, is approved, and treatment is
complicated by toxic side effects.
Despite chemotherapy forming current standard
first-line regimen for castration-resistant prostate cancer, this
therapy is not appropriate for at least 25% of patients for various
reasons, including old age, poor performance status, or toxicity
concerns. This indicates a potential opportunity for drug
developers, as there is a high unmet need for a more tolerable
agent in patients who may be too ill to undergo chemotherapy or
unwilling to put up with the severe side effects.
