New Strategies for Prostate Cancer Care Demanded by
Longer Life Expectancy, Aging Population
As boomers pass age 65 – the most common time of
prostate cancer diagnosis – researchers have a handful of new barriers
to put in the path of the disease
By Garth Sundem, University of Colorado Cancer
Dec. 4, 2012 - The population of the United States
is getting older, due not only to aging boomers but also to a four-year
increase in life expectancy from 1990 to 2010. An aging population means
increased diagnosis of prostate cancer. Statistically, the older the
patient at time of diagnosis, the more aggressive the disease – and also
the less well the patient is likely to tolerate traditional
chemotherapies. In sum, we have more, aggressive prostate cancer that
can’t be targeted by traditional treatments.
Members of the
University of Colorado Cancer Center
recently published a review in the journal
Drugs and Aging
describing the modern state of prostate cancer care – examining not only
new drugs but entirely new classes of drugs that may be effective and
well-tolerated in these aging patients.
“For patients with advanced prostate cancer, there
are more options than ever before. But with more options comes a more
complex decision tree in choosing appropriate therapies,” says Elizabeth
Kessler, MD, oncology fellow at the University of Colorado Cancer Center
and the review’s lead author.
First among these options are targeted therapies.
Modern targeted therapies are able to selectively kill cancer cells as
opposed to accepting high collateral damage in healthy tissue and so
frequently have fewer side effects than traditional chemotherapies.
(And, are thus better tolerated by elderly patients.)
“These are drugs like abiraterone and enzalutamide
that have been approved for use in late stage prostate cancer and are
now being evaluated for earlier use,” Kessler says. Prostate cancer
generally depends on androgen hormones like testosterone to survive and
grow – even after traditional hormone blockade, the body continues to
produce minute amounts of testosterone and even this little bit is
enough to drive prostate cancer.
By completely removing the body’s ability to
produce testosterone or the cancer’s ability to use it, these drugs
break the messaging chain that tells prostate cancer to grow. CU Cancer
Center researchers have played an important role in the clinical
development of both of these drugs.
Researchers are also looking for additional,
molecular drivers of prostate cancer, perhaps for example insulin growth
“We’re also exploring the use of targeted kinase
inhibitors,” Kessler says. For example, the drug known as XL184 by
Exelixis is currently in clinical trials to target MET and VEGF, “and
appears to show effect against bone lesions, the most common location of
prostate cancer metastasis,” Kessler says.
“Another promising strategy to treat metastatic
prostate cancer is immunotherapy,” Kessler says. In immunotherapy,
drugs, devices or treatments are used to sensitize the body’s immune
system to attack cancer cells – boosting the body’s ability to clear
itself of cancer.
For example, the drug Sipuleucel-T was approved by
the FDA in 2010 for treatment of metastatic prostate cancer – “but it
requires blood to be removed, treated, and reinfused,” Kessler says – a
procedure that can only be accomplished by shipping the patient’s blood
to facilities in other cities before reinfusing it here. Second
generation prostate cancer immunotherapies including Prostvac are in
development or clinical trials, including an open trial at the CU Cancer
Finally, researchers are exploring ultra-precise
targeting of radiation that rides along with drugs that attach to bone
metastases and affects only the tumor cells in the immediate areas of
attachment. “One of these drugs is Alpharadin,” Kessler says, “which
goes only shallowly into bone and so targets lesions without stopping
the production of bone marrow.”
“There has been a major shift in the acceptance of
these drugs,” Kessler says. “We’re learning to reach for them sooner and
more frequently in place of traditional chemotherapies.”
This shift means that just as boomers pass age 65 –
the most common time of prostate cancer diagnosis – researchers have a
handful of new barriers to put in the path of the disease.
Cancer Statistics 2011 shows among men the
reduction in lung, prostate, and colorectal cancers is nearly 80% of
decline; among women, almost 60% of decrease in breast and colorectal -
see chances of seniors getting cancer - June 17, 2011