Why
are Vietnam veterans worried about prostate cancer?
Prostate
cancer is one of the most common cancers among men.
The rate varies dramatically by age and race. The risk of getting prostate cancer increases fivefold
between the ages of 45-49 and 50-54 years, and nearly triples between 50-54 and
55-59. African-American men have
the highest recorded incidence of prostate cancer in the world.
Their risk is approximately double that of white men.
The causes of prostate cancer are uncertain.
Risk factors other than race and age include a family history of the
disease and a diet high in fats. Prostate
cancer is expected to account for about 29 percent of new diagnoses and 13
percent of cancer death per year in the United States.
Some
Vietnam veterans have already reached, while many are approaching, the age when
prostate cancer is typically detected. Since
prostate cancer is a slow-growing tumor, many men diagnosed with prostate cancer
will actually die from other unrelated causes.
Nevertheless, prostate cancer is the second leading cause of death in
men. It is estimate that more than
200,000 cases of prostate cancer (including about 10,000 veterans) will be
diagnosed annually with an approximately 40,000 death.
A problem with prostate cancer is that in about 40 percent of the cases
the tumors have spread beyond the prostate before it is diagnosed, making
treatment more difficult.
How
is prostate cancer detected?
There
are currently three methods of screening: (1)
digital rectal examination, (2) transrectal ultrasound, and (3) prostate
specific antigen (PSA, a blood test to measure a protein found only in prostate
tissue). Unfortunately, there are
significant problems with each of these screening techniques.
For each cancer detected, there are many false positives that may
incorrectly diagnose a patient as having prostate cancer.
What
treatments are available?
Since
prostate cancer is a relatively slow-growing tumor compared to other cancers,
the paradox in managing it is the need to intervene early to stop the disease
and also being cautious about using the major treatment, a surgery known as
radical prostatectomy. This is a
serious procedure with significant complications.
From 25 to 75 percent of patients will be impotent and 2 to 6 percent
severely incontinent after the surgery.
In
addition to surgery, current treatments for prostate cancer include radiation
therapy, which also has some unpleasant side effects, and male hormone
(androgen) deprivation. Chemical or
surgical deprivation or administration of estrogen is effective in relieving
pain, reducing urinary obstruction, and improving general well-being.
Endocrine therapy delays disease progression, but has not been shown to
prolong survival.
A
relatively new approach to treatment is known as “expectant management,”
which means following the patient and giving hormonal or surgical treatment as
necessary. This approach is
reasonable because the progression of the tumor for each patient is uncertain,
the treatment effectiveness is uncertain, and many patients with prostate cancer
eventually die of other causes.
What
did the National Academy of Sciences (NAS) conclude about the relationship
between exposure to herbicides and the development of prostate cancer in its
1993 report, entitled Veterans and Agent Orange - Health Effects of
Herbicides Used in Vietnam?
The
NAS reviewers observed that most of the agricultural studies they examined
indicate “some elevated risk” of prostate cancer.
Furthermore, one large well-done study in farmers showed an increased
risk, and subanalyses in this study indicate that the increased risk
specifically associated with herbicide exposure. The three major production worker studies reviewed by the NAS
all show a small, but not
statistically significant, elevation in risk.
The NAS report noted that most of the associations seen in the studies
reviewed are “relatively weak.” The
NAS added that Vietnam veterans have “not yet reached the age when this cancer
tends to appear.” In the report
released in July 1993, the NAS concluded that there is “limited/suggestive
evidence” of an association between exposure to herbicides used in Vietnam and
prostate cancer.
What
action did VA take in response to this NAS finding?
In
its July 1993 report, the NAS placed three health outcomes in its second highest
category of association (limited/suggestive evidence of an association):
multiple myeloma, respiratory cancers, and prostate cancer.
After careful review, VA’s Secretary Brown concluded that the credible
scientific evidence for an association is equal to or outweighs the evidence
against an association between exposure to herbicides used in Vietnam and the
development of multiple myeloma and of respiratory cancers.
On the other hand, the evidence for an association between these
herbicides and prostate cancers failed to reach that standard.
In
January 1994, VA published a notice in the Federal Register that
Secretary Brown has determined that a presumption of service connection based on
exposure to herbicides used in Vietnam is not warranted for a long list of
conditions identified in the NAS report. Prostate
cancer was included in this list. (See
59 Fed. Reg. 341, January 4, 1994).
VA
asked the NAS, in its follow-up report, to further consider the relationship
between exposure to herbicides and the subsequent development of prostate
cancer.
What
did the 1996 NAS update conclude about prostate cancer?
Citing
additional studies, the NAS report concluded that there is “limited/suggestive
evidence” of an association between exposure to herbicides used in Vietnam and
prostate cancer.
What
was VA’s response to the NAS 1996 finding regarding prostate cancer?
Secretary
Brown found that the credible evidence for an association equals or outweighs
the evidence against an association between exposures to herbicides used in
Vietnam and prostate cancer. He
concluded that prostate cancer should be added to the list of conditions
recognized for presumption of service connection for Vietnam veterans based on
exposure to herbicides. President
Clinton announced this, along with other decisions, on May 28, 1996. The proposed rule to implement this decision was published
for public comment in the Federal Register in August 1996.
(See 61 Fed. Reg. 41368, August 8, 1996). The final rule was
published in the Federal Register in November 1996.
(See 61 Fed. Reg. 57587, November 7, 1996).
What
did the subsequent NAS updates conclude about prostate cancer?
The
1998 report concludes that there is limited/suggestive evidence of an
association between exposure to the herbicides used in Vietnam and prostate
cancer. The report includes the
following statement:
Although the associations are not large, a number of studies provide evidence that is suggestive of a slight increase in either morbidity or mortality from prostate cancer. The evidence regarding association is drawn from occupational studies in which subjects were exposed to a variety of herbicides and herbicide components and is also based on data from studies of Vietnam veterans. An important consideration is the fact that prostate cancer tends not to be fatal; thus, mortality studies have lower statistical power to detect a comparable effect than a similar-sized morbidity study would have.
In the 2000 update, the NAS concluded that there is limited/suggestive evidence between exposure to herbicides and prostate cancer. Although the associations are not large enough, there are a number of studies providing evidence suggestive of a small increase in either morbidity or mortality from prostate cancer.
The
2002 report also concludes there is limited/suggestive evidence of prostate
cancer being linked to exposure to herbicides.
The associations are not large but there are studies providing evidence
that suggest a small increase in either morbidity or mortality from prostate
cancer.
Information regarding prostate cancer and related matters can be obtained at VA medical center libraries, from the Environmental Health Clinicians at every VA medical center, or from the Environmental Agents Service (131), Department of Veterans Affairs, 810 Vermont Avenue, N.W., Washington, DC 20420.
The October 2001 and March 2002 issues of the VA’s Agent Orange Review newsletter reprint in two parts an excellent brochure provided by the American Urological Association (AUA). The Web address for the AUA is www.auanet.org. The Agent Orange Review can be seen at the Web site listed below.
Where
can a veteran get additional information regarding Agent Orange – related
issues?
The
following Agent Orange Brief fact sheets (including the one you are reading) are
available on the World Wide Web at www.va.gov/AgentOrange:
A1.Agent Orange - General Information; A2.Agent
Orange Class Action Lawsuit; B1.Agent
Orange Registry Program; B2.Agent
Orange – Health Care Eligibility; B3.Agent
Orange and VA Disability Compensation; B4.VA
Information Resources on Agent Orange and Related Matters; C1.Agent Orange – The Problem Encountered in Research; C2.Agent
Orange and Vietnam Related Research – VA Projects; C3.Agent
Orange and Vietnam Related Research – Non-VA Projects; D1.Agent Orange and Birth Defects; D2.Agent Orange and Chloracne; D3.Agent
Orange and Non-Hodgkin’s Lymphoma; D4.Agent
Orange and Soft Tissue Sarcomas; D5.Agent
Orange and Peripheral Neuropathy; D6.Agent
Orange and Hodgkin’s Disease; D7.Agent
Orange and Porphyria Cutanea Tarda; D8.Agent
Orange and Multiple Myeloma; D9.Agent
Orange and Respiratory Cancers; D10.Agent
Orange and Prostate Cancer; D11.Agent
Orange and Spina Bifida; D12.Agent
Orange and Diabetes; and D13.Agent Orange and Chronic Lymphocytic
Leukemia. Hard copies can be obtained
from local VA medical centers or from the VA Central Office at the Environmental
Agents Service (131) Department of Veterans Affairs, 810 Vermont Avenue, N.W.,
Washington, DC 20420.
At the same Web site you will find copies
of past and current issues of the “Agent Orange Review” newsletter and other
items of interest.
This fact sheet was updated in late October 2003 and does not include any subsequent developments.