Breaking new ground in the treatment of prostate cancer
A new 10-year study of 800 Australian and New Zealand men finds that the most successful way to treat locally advanced prostate cancer is with a combination of hormone treatments and radiotherapy.
Each year, more than 5,000 Australian men are diagnosed with
'locally advanced' prostate cancer - tumours that are often
inoperable because surgery cannot fully extract all the remnants of
the cancer.
Many of these men also face the problem that their cancer has
already spread to other parts of the body, commonly the lymph
glands of the abdomen or the bones of the trunk, prior to their
primary cancer being diagnosed.
These men face a very real risk that their cancers could cause
further harm or death within five years. This is because the
primary cancer in the prostate will become dangerously enlarged and
block the flow of their urine, or because secondary cancers (i.e.
cancerous spread) grow to dangerous sizes causing pain and other
manifestations of advanced cancer.
Prior to the early 1990s the preferred treatment method of
locally advanced prostate cancer involved radiation therapy alone.
Unfortunately, this did not produce satisfactory reductions
in recurrence of the primary cancer or the development of
secondary cancer.
The combination of hormone treatment and
radiotherapy is much more successful in treating the primary tumour
in the prostate than radiotherapy alone.
This led to trials of short-term neo-adjuvant and long-term
adjuvant (supplementary) hormone treatment throughout the 1990s,
which resulted in improved outcomes. The hormone treatment
uses drugs to starve prostate cancer cells of testosterone. This
kills massive numbers of cancer cells wherever they are in the
body, but not all. Radiotherapy is then applied to the primary
tumour in the prostate because this is where most cancer cells are
located.
There were, however, documented cases of serious, unwanted side
effects from the long-term use of androgen deprivation therapy,
such as prolonged sexual dysfunction, permanent hypogonadism,
osteoporosis, muscular atrophy, anaemia as well as cognitive
disturbances and depression.
Researchers from the Australian and New Zealand Trans Tasman
Radiation Oncology Group (TROG) set out to examine cases of locally
advanced prostate cancer in more detail in an attempt to identify
the optimum duration of the hormone treatment. In what became
the largest treatment trial for any type of cancer in Australia and
New Zealand, more than 800 eligible men took part (known as TROG
96.01).
The TROG 96.01 trial, coordinated by Professor Jim Denham from
the University of Newcastle, involved 19 cancer centres across
Australia and New Zealand and tested the value of attacking the
cancer on two flanks: short-term hormone treatment and
radiotherapy.
The 10-year results of the study, published
recently in Lancet Oncology, found the combination of
hormone treatment and radiotherapy was much more successful in
treating the primary tumour in the prostate than by radiotherapy
alone and also reduced cancerous spread.
Specifically the study showed:
- The chances of cancer returning were reduced by up to 60 per
cent following six months of hormone treatment.
- The risk of cancer spreading to other parts of the body fell by
50 per cent.
- The number of deaths due to cancer also halved.
Importantly, the trial also found that supplementary hormone
therapy for a period of up to six months only added temporary side
effects and inconvenience to patients and dissipates following
conclusion of the treatment.
This combination of hormones and radiotherapy has become today's
standard of care for locally advanced prostate cancer.
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