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.
Where can a veteran get additional information about 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.