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  • Writer's pictureSuzanne Caruso

Cancers Dismissed by the VA Based on Dated Science

Updated: Jan 29

The VA M21-1 Adjudication Manual, the published procedures for VA employees who rate and determine service connection for Veterans, includes a list of specific cancers that the VA claims are

“not associated with herbicide exposure.”


And, since the specific toxins found in herbicides are also independently present at many military locations today, the ramifications of the VA’s exclusion list reaches far beyond Vietnam & Agent Orange.


In November of 2023, a highly credentialed Medical Expert in the Field of Oncology performed an important analysis of the VA’s exclusion list. His conclusions were eye-opening. The M21-1 Manual, the very guidelines used to evaluate service connection for Veteran claims, is tragically wrong.


Along with his worldwide contributions, this distinguished Scientist has worked with us for over six years supporting Veterans by authoring Nexus Opinions. As such, we are privy to this work, and with his permission to distribute,

we hope you find this analysis as valuable as we do.


Suzanne M. Caruso

Director, Case Management

Correcting the Science on Behalf of Veterans - Dioxin, Benzene, Arsenic

The M21-1 Analysis


The objective of this analysis is to review those cancers on the VA’s "not associated with  herbicide exposure" list which are being unfairly categorized and tragically overlooked.  I predict that many cancers on this list will one day follow the example of Bladder Cancer, where the VA ultimately recognized its validity for service connection relative to herbicide exposure.  Until then, every Veteran’s case should be considered individually on its merits, and not be categorically dismissed based simply on a questionable exclusion list unfortunately put into practice by the VA.

The information used in this analysis comes from:

M21-1, Part VIII, Subpart I, Chapter 1, Section B – Ratings for Disabilities Associated with Herbicide Exposure

Under the heading: (live link)

In this section, the VA publishes a list of cancers and other diseases that it asserts:

“Based on cumulative scientific data reported by NAS since 1993, the Secretary has determined that a positive association does not exist between herbicide exposure and the following conditions and that a presumption of SC is not warranted for any of the conditions:”

“Note:  No positive association means that the evidence for an association does not equal or outweigh the evidence against association”


It is well known that the VA relies upon the National Academies of Sciences (NAS) reports to grant or deny service connections based on toxic exposure and specifically, to herbicides. Within the VA’s M21-1 Adjudication Manual, also known as the “VA Rater Handbook”, a specific list of cancers and other diseases are cited that the VA asserts are “not associated with herbicide exposure”. For all practical purposes, this is an “auto-deny” list, and unfortunately, it causes Veteran Advocates to turn away cases where herbicide exposure could be linked to one of the listed diseases. This is both unfortunate and unfair to Veterans who suffer greatly as a result of herbicide exposure, and it is also critically important to their surviving spouses.

The NAS report that the VA relies on was last updated in 2018, in Update No. 11.  Not only is the update more than 5 years old but the research publications it relied upon date back several additional years.  The resulting effect is that the basis for the VA’s M21-1 exclusion list lags behind the scientific evidence by as much as 10 years, or even longer.  A good example of this lag is Bladder Cancer, which only made the presumptive list in 2021.  However, numerous animal studies, epidemiological studies, and meta-analyses had convinced the scientific and medical communities (and everyone else) for over 5 years prior to 2021 that exposure to these herbicides can cause Bladder cancer.

Herbicide Toxins: Vietnam and Beyond

Herbicide exposure includes Agent Orange (which contains Dioxin) as well as Agent Blue (which contains Arsenic).  Furthermore, Agent Orange was diluted in practice with Jet fuel or Diesel to facilitate spraying, and thus exposure to Agent Orange should also include exposure to Benzene within these fuels, which is relevant for several cancers, including Leukemia.

It should also be noted that the toxins present in Herbicides, Dioxin, Benzene, and Arsenic, are also found in many military environments beyond Vietnam. This would include Dioxin & Benzene in Burn Pits (per the Pact Act of 2022), and Camp Lejeune and other Superfund Sites contaminated with Benzene and Arsenic. Therefore, the evidence that will be presented here is relevant beyond “herbicides” and beyond Vietnam.  These toxins are present in many military installations and the evidence below travels with the toxin, no matter where it is located.

Included in this analysis is TABLE 1, which outlines the diagnoses and analysis for cancers that the VA incorrectly claims: “a positive association does not exist” with herbicide exposure.

How the Strength of Each Connection is Determined [A]

The link between exposure and diagnosis derives from Epidemiological studies, the size of the effect between exposure and diagnosis, and whether a meta-analysis of multiple Epidemiological studies exists. [B] The 4 levels used in Table 1 indicate the strength of the research in support of a connection.

The indices used are: Strong, Very Good, Good, and Too Weak. 

  • Strong: based on published meta-analyses of Epidemiological studies, which are the strongest evidence available.

  • Very Good, or Good: when several Epidemiological studies consistently demonstrate a link.

  • Too Weak: when there aren’t sufficient supporting studies available yet.


The Competing Personal Risk Factors

When evaluating any Veteran case, one must weigh the supporting evidence of a link with herbicide exposure, against the competing personal risk factors for a particular disease.  Hence, every case must be considered individually.  Some risk factors are more important than others, and so each risk factor must be quantified.  Also consider that some risk factors may themselves be service-connected, often based on herbicide exposure.  For instance, Hypertension is an herbicide presumptive, which is also linked with Kidney cancer.  Similarly, Diabetes is another herbicide presumptive and is linked with multiple cancers.  Table 1 below lists risk factors to consider.  This list is a starting point, representative, and not exhaustive.


TABLE 1: Evidence in Support of a Link Between Herbicide Exposure

and the Cancers on the M21-1 “Not Associated with Herbicides” List


Vietnam herbicide exposures include the carcinogens Dioxin, Arsenic, and Benzene. The list published in the VA’s M21-1 Adjudication Procedures Manual, which asserts that the listed cancers and diseases are “not associated with herbicide exposure”, relies on dated science and is incorrect. Every Veteran’s case deserves fair consideration. Veteran Advocates should be keenly aware that Table 1 outlines potential pathways to connection based on current and reliable medical and scientific data. The analysis is also specific to the toxin; meaning that support for the connection applies to any military location where the toxin is present.

To reflexively deny any Veteran case based solely on the M21-1 list deprives Veterans and their surviving spouses of the consideration they deserve, and are entitled to.



[A] The “Risk” percentage cited in Table (1) is the incremental risk to individuals who were exposed versus individuals who were not exposed. So, if in a group of 100 people not exposed to the toxins found 10 incidences of Thyroid Cancer, and then in a group of 100 people who were exposed to the toxins found 20 incidences of Thyroid Cancer, then the ratio is 2:1. Meaning: Those individuals exposed to the toxins have a 100% higher risk of Thyroid Cancer compared to those not exposed.

[B] A meta-analysis is a powerful statistical tool combining the results from multiple epidemiological studies to derive  robust quantitative estimates between exposure and diagnosis.

[1] Head & Neck cancers: includes tongue, oral cavity, nasopharynx, tonsils, and pharynx.

[2] Leukemia: includes AML, CML, ET, PCV, MDS, all Myeloproliferative Neoplasms.

[3] Gastrointestinal cancers: includes esophagus, stomach, small bowel, colon, rectum.

[4] Breast cancer: male and female.

[5] Skin cancers: includes Basal Cell Carcinoma, Squamous Cell Carcinoma, Melanoma.

[6] Brain cancers: includes Glioblastoma Multiforme, all Gliomas, Astrocytoma.



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