Citation Nr: 21001833 Decision Date: 01/12/21 Archive Date: 01/12/21 DOCKET NO. 09-33 575 DATE: January 12, 2021 ORDER Entitlement to service connection for cause of death is denied. Entitlement to service connection for basal cell and squamous cell carcinoma of the skin, claimed as due to exposure to herbicide agents, for accrued benefits purposes is denied. FINDINGS OF FACT 1. The Veteran died in August 2008. His death certificate listed recurrent squamous cell carcinoma of the head and neck as the primary cause of death. 2. The Veteran’s death was not caused, or contributed substantially or materially to, by a service-connected disability. 3. The preponderance of the evidence is against finding that basal cell and squamous cell carcinoma of the skin began during active service, or is otherwise related to an in-service injury or disease. CONCLUSIONS OF LAW 1. The criteria for service connection for the cause of the Veteran’s death have not been met. 38 U.S.C. §§ 1110, 1310, 5107; 38 C.F.R. §§ 3.303, 3.307, 3.309, 3.312. 2. The criteria for service connection for basal cell and squamous cell carcinoma of the skin are not met. 38 U.S.C. §§ 1110, 1131, 5107; 38 C.F.R. §§ 3.102, 3.303. REASONS AND BASES FOR FINDINGS AND CONCLUSIONS The Veteran had active service from January 1968 to January 1969. The appellant is his surviving spouse. This matter comes before the Board of Veterans’ Appeals (Board) on appeal from a January 2009 rating decision by a Department of Veterans Affairs (VA) Regional Office (RO). The Veteran testified before the undersigned Veterans Law Judge at a hearing in August 2013. A transcript is of record. Briefly, this appeal was originally denied by the Board in a July 2014 decision. The appellant appealed the Board’s decision to the United States Court of Appeals for Veterans Claims (Court). By way of an April 2015 Order, the Clerk of the Court granted a Joint Motion for Remand (JMR) which vacated the Board’s decision and remanded the matter for adjudication consistent with its terms. Following additional development, the Board again denied this appeal in April 2018. The appellant appealed the Board’s 2018 decision to the United States Court of Appeals for Veterans Claims (Court). In a July 2019 memorandum decision, the Court vacated the Board’s decision and remanded the matter for adjudication consistent with its terms. In April 2020 the Board remanded the case for additional development, which has since been completed. 1. Entitlement to service connection for cause of death The appellant seeks service connection for the cause of the Veteran’s death. The Veteran and the appellant asserted that the disease is due to exposure to Agent Orange. The appellant reported the Veteran believed he had the carcinoma for a long time, and the Veteran’s previous representative testified that the Veteran contended his disease had its onset during service. Service connection may be granted for disability resulting from disease or injury incurred in or aggravated by active service. 38 U.S.C. §§ 1110, 1131, 5107; 38 C.F.R. § 3.303. The three-element test for service connection requires evidence of: (1) a current disability; (2) in-service incurrence or aggravation of a disease or injury; and (3) a causal relationship between the current disability and the in-service disease or injury. Shedden v. Principi, 381 F.3d 1163, 1166 -67 (Fed. Cir. 2004). Service connection for the cause of a veteran’s death is warranted if a service-connected disability either caused or contributed substantially or materially to the cause of death. 38 C.F.R. § 3.312. The death of a veteran will be considered as having been due to a service-connected disability when the evidence establishes that disability was either the principal or a contributory cause of death. 38 C.F.R. § 3.312 (a). A service-connected disability will be considered as the principal, or primary, cause of death when that disability, singly or jointly with some other condition, was the immediate or underlying cause of death or was etiologically related thereto. 38 C.F.R. § 3.312 (b). For a service-connected disability to be the principal cause of death it must singly or with some other condition be the immediate or underlying cause of to be etiologically related. 38 C.F.R. § 3.312(b). For a service-connected disability to be a contributory cause of death, it must be shown that it contributed substantially or materially; it is not sufficient to show that it casually shared in producing death, rather there must be a causal connection. 38 C.F.R. § 3.312(c). In October 2006, a squamous cell carcinoma was partially excised from the left floor of his mouth. Treatment records reflect that the disease spread to the tongue, mandible and ultimately the neck and lymph nodes. The Veteran died in August 2008. The Veteran’s death certificate documents that he died in August 2008. His immediate cause of death was listed as recurrent squamous cell carcinoma of the head and neck, and oral cutaneous fistula. The Veteran’s service records indicated he served in the Republic of Vietnam during active service; therefore, he is presumed to have been exposed to an herbicide agent such as Agent Orange. Squamous cell carcinoma is not a chronic disease under 38 C.F.R. § 3.309 (a) associated with exposure to herbicide agents. Even if service connection is not warranted on a presumptive basis, if exposure to herbicide agents is presumed, the effects of that exposure must be considered on a direct basis. Combee v. Brown, 34 F.3d 1039 (Fed. Cir. 1994). An advisory medical opinion from a VHA oncologist was received in March 2014. The adequacy of this opinion was the subject of a JMR. Both parties to the JMR agreed that the opinion was inadequate because the examiner applied a higher standard than required by law. As a result, the Board will disregard this opinion in its adjudication herein. In a December 2007 private treatment record, Dr. J.M. wrote that the Veteran and the appellant inquired regarding the evidence of Agent Orange as an etiologic factor in the development of the carcinoma. Dr. J.M. explained that there are cases in which exposure to toxic carcinogens have led to the development of squamous cell carcinoma. Dr. J.M. did note that the Veteran had a history of smoking and alcohol use, which are causative factors for the disease; however, as he had been exposed to Agent Orange, the possibility of that as an etiologic agent should not be overlooked. In a February 2008 letter, Dr. Z.S. wrote that the Veteran asked him to write this letter on his behalf as he acknowledges being exposed to Agent Orange. Dr. Z.S. added that the Veteran has a history of smoking and alcohol exposure. Dr. Z.S. wrote that all three factors have shown to be toxic carcinogens and, certainly, agents that could potentially lead to the development of malignancy in the head and neck region. In a March 2008 VA treatment record, Dr. F.M. wrote that the Veteran inquired about the relationship of his tumor to Agent Orange. Dr. F.M. explained that there have been reported cases of squamous cell carcinoma of the head and neck associated with Agent Orange exposure in the past. In a May 2016 VA medical opinion and addendum, a VA examiner concluded that it was less likely than not that the Veteran’s disease was incurred in or caused by the claimed in-service injury, event, or illness. The examiner noted that squamous cell carcinoma of the floor of the mouth is not considered a presumptive disease associated with Agent Orange exposure. The examiner noted that the Mayo Clinic shows major risk factors for developing squamous cell cancer of the mouth include smoking and ETOH. Applied to the Veteran’s case, his history shows he was a long-term smoker and that he did consume alcohol. The examiner noted that the Merck Manual shows that oral squamous cell carcinoma affects about 30,000 people in the U.S. each year, and over 95 percent of those affected smoke tobacco, drink alcohol, or both. The examiner considered the medical opinions of Drs. J.M. and Z.S. but noted that they did not refer to any medical literature supporting a relation between the exposure to Agent Orange and the oral carcinoma. Instead, the examiner favored his review of well-regarded medical journals (Mayo, Merck, etc.) that did support a direct nexus between smoking and alcohol use and the development of oral cancer and did not even mention Agent Orange as a risk factor. The examiner concluded that the majority of medical evidence points to the Veteran’s oral cancer being caused by his lifelong extensive history of smoking and alcohol consumption. In December 2017, VA received an IME opinion from an Assistant Professor of Otolaryngology/Head and Neck Surgery. The expert opined that the Veteran’s squamous cell carcinoma was less likely than not related to his herbicide exposure and more likely than not related to his known history of smoking and alcohol abuse. The expert reasoned that tobacco and alcohol use are well-established risk factors for head and neck carcinogenesis and in combination have demonstrated a synergistic effect. For the combination of heavy tobacco and alcohol use, there can be as high as a 300-fold increase in oral cavity cancer compared to nonsmokers and non-drinkers of alcohol. The expert considered the potential association between herbicides such as Agent Orange and head and neck cancer but found that the data was limited. The expert discussed a unique study of 180,000 Korean soldiers who were exposed to Agent Orange during the Vietnam War; the data was further stratified into groups of high and low exposure. Based on the study, the adjusted hazard ratio for cancers of the mouth was significantly higher in the high-exposure group versus the low-exposure group. On a granular level, 9 individuals in the low-exposure group and 23 individuals in the high-exposure group developed a mouth cancer. The authors of the study also analyzed tongue cancer separately and found the difference not to be significant. Skin cancer other than melanoma was also not significant. The authors of the study noted that the exposure index may be limited in terms of accuracy and precision and further concede that there may be a bias in the relationship between Agent Orange and cancer. Additionally, there was a 19-year lag between the creation of this cohort database and the return of these soldiers from war, and a temporal relationship with exposure and cancer development is uncertain. Finally, the study did not adjust for smoking or alcohol consumption. Given the foregoing, the expert found that the Veteran’s squamous cell carcinoma were less likely than not related to his herbicide exposure and more likely than not related to his smoking and alcohol use. In support of her claim, the appellant submitted a medical opinion by Dr. C.K. dated February 2020. He noted that the Veteran was diagnosed with invasive squamous cell carcinoma of the floor of the mouth in October 2006. He opined that it is at least as likely as not that the Veteran’s floor of the mouth cancer was caused by his exposure to Agent Orange during service in Vietnam. He indicated that the primary known risk factors for cancers of the oral cavity include alcohol abuse and smoking. He noted that the Veteran had smoked a pack of cigarettes per day and drunk 2 to 8 beers per day for the previous 40 years. However, he also stated that Dioxin or Agent Orange is a carcinogen. He opined that it is impossible to identify the specific carcinogen, or combination of carcinogens, that was the ultimate trigger of the Veteran’s oral cancer. He stated that any carcinogen has the potential to cause, or interact with other carcinogens to cause, any cancer. Thus, he concluded it is at least as likely as not the Veteran’s oral cancer was related to exposure to Agent Orange during service. In a July 2019 memorandum decision, the Court vacated the Board’s April 2018 decision that had denied the appeal. Specifically, the Court found that the Board did not sufficiently explain how it could rely on the May 2016 VA medical opinion and December 2017 IME report to deny service connection for the Veteran’s skin cancer. It noted that both opinions focused on squamous cell carcinoma of the mouth, and that the May 2016 VA examiner did not mention skin cancer at all in his opinion. Therefore, the Court found that the opinions provided no basis on which the Board could conclude the Veteran’s skin cancer was not related to Agent Orange exposure. The Court also highlighted the potentially contradictory findings in the May 2016 VA opinion. Specifically, the examiner referenced a Mayo clinic journal to support his conclusion. However, as the appellant’s brief pointed out, a Mayo clinic article on squamous cell carcinomas of the skin noted a positive association between exposure to toxic substances, including herbicides, and the development of the condition. The Court directed the Board to evaluate these apparent contradictions pursuant to McCray v. Wilkie, 31 Vet. App. 243 (2019). Following the July 2019 memorandum decision, the Board remanded the appeal for an addendum opinion. In July 2020, a VA examiner reviewed the evidence and offered an addendum opinion. He opined that the Veteran had two separate cancers: oral squamous cell carcinoma (also identified as floor of the mouth cancer, oral cancer, and head and neck cancer), and basal cell and squamous cell skin cancer. He explained that cancers are often identified by the specific type of cell that becomes malignant. He noted that squamous cells are found in multiple areas, such as the skin, oral pharynx, respiratory, and the gastrointestinal tract. Each area is considered a separate type of cancer with different epidemiology, risk factors, treatment, and prognosis. With respect to the cancer found in the mouth, floor of the mouth, oral cancer, and head and neck cancer mattered only in attempting to more specifically identify where the lesion started. Oral cancer had risk factors of smoking and alcohol. This was noted as different than the squamous cell carcinoma of the skin, which had a risk factor of ultraviolet exposure in sun-exposed areas. Further, he explained that skin cancer usually spreads by direct extension, thus if the Veteran’s oral cancer was from his skin cancer there would be an obvious skin cancer overlying the same region. Further, if the Veteran’s skin cancer were to metastasize it would typically spread to the parotid lymph nodes, which was not where the Veteran’s oral cancer was found. Thus, he concluded that the Veteran had two separate cancers: 1) oral cancer and 2) cutaneous basal/squamous cell cancer. Given the July 2020 VA examiner’s conclusion, the Board finds that the May 2016 VA opinion and December 2017 IME opinion addressed the Veteran’s oral squamous cell carcinoma, but did not evaluate or offer clear opinions with respect to the skin cancer. Based on consideration of all of the evidence of record, the Board finds the evidence does not establish a nexus between the Veteran’s oral carcinoma and his active service, to include exposure to herbicide agents such as Agent Orange. The record contains conflicting medical opinions regarding whether the Veteran’s oral squamous cell carcinoma is at least as likely as not related to an in-service injury, event, or disease, including Agent Orange exposure. Taken together, the VA opinions of record establish that the Veteran’s oral cancer is not at least as likely as not related to an in-service injury, event, or disease, including Agent Orange exposure. The May 2016 VA examiner and the December 2017 IME expert opined that the Veteran’s oral cancer was not at least as likely as not related to Agent Orange exposure. Both examiners considered that there have been reported cases of an association, but found that the well-regarded medical literature weighs against such a causal connection in this case. The May 2016 VA examiner referenced medical literature from the Mayo Clinic and Merck Manual to support this conclusion. The Board acknowledges that the Mayo Clinic report shows an association between exposure to herbicides and squamous cell carcinoma of the skin. See Mayo Clinic, Squamous Cell Carcinoma of the Skin (Dec. 14, 2018). However, as noted by the July 2020 addendum opinion, squamous cell carcinoma of the mouth and squamous cell carcinoma of the skin are considered separate types of cancer, with different epidemiology, risk factors, treatment, and prognosis. Considering the explanation provided by the examiner, and the fact that the Mayo Clinic report cited by the appellant is not relevant to the May 2016 VA examiner’s opinion regarding the Veteran’s oral cancer, any potential inconsistencies in this medical literature on which the examiner relied does not serve to undercut the evidentiary weight the Board has afforded to the opinion. See McCray v. Wilkie, 31 Vet. App. 243 (2019). The expert who authored the IME opinion even referenced a study of 180,000 soldiers that had been exposed to Agent Orange during the Vietnam War that had found some soldiers had developed oral or tongue cancer. The results of the study were ultimately negative, however, and the authors of the study acknowledged the possibility of bias in the relationship between Agent Orange and cancer. The expert noted that the study had not adjusted for soldiers who had used alcohol or tobacco, well-known risk factors for squamous cell carcinoma. The expert also highlighted that the combination of heavy tobacco and alcohol use, as had been used by the Veteran, produces a synergistic effect that could result in as high as a 300-fold increase in oral cavity cancer compared to nonsmokers and non-drinkers of alcohol. Thus, the expert who authored the IME opinion did consider that there have been cases where Agent Orange exposure was associated with oral cancer but ultimately an etiological relationship could not be shown and well-known literature regarding risk factors specifically pertinent to the Veteran’s medical history indicated those risk factors were more likely than not the cause of the condition. Finally, the July 2020 VA examiner clarified that the Veteran had two separate cancers. The examiner noted that the Veteran had been treated for skin cancer, both basal cell carcinoma and squamous cell carcinoma. Records documented treatment for skin cancer, including the removal of a lesion on the Veteran’s forehead. The Veteran had also been treated for an oral squamous cell carcinoma, identified at different locations in the medical record as floor of the mouth cancer, oral cancer, and head and neck cancer. The examiner explained that oral cancer and skin cancer had different risk factors, treatment, and prognosis. He indicated that oral cancer was related to smoking and alcohol use, while skin cancer was related to UV exposure. Additionally, if the Veteran’s oral cancer had metastasized from a skin cancer, there would have been an obvious cutaneous squamous cell carcinoma overlying the area, but this was not in the record. Lastly, he noted that none of the Veteran’s treating physicians had recognized the oral cancer as due to spread from the skin, but rather a primary cancer itself. Thus, he concluded the Veteran’s oral cancer was separate from his documented skin cancer. The examiners’ combined opinions are probative because they are based on an accurate medical history and provide an explanation that contains clear conclusions and supporting data. Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 304 (2008). The opinions of Drs. J.M. and Z.S. indicate the Veteran’s oral carcinoma could be related to his exposure to Agent Orange. To the extent that they provide a linkage opinion, the Board finds they are too speculative. See Bloom v. West, 12 Vet. App. 185, 187 (1999). Conversely, those two opinions, as well as the one provided by Drs. F.M. and Dr. C.K., do provide competent evidence that exposure to Agent Orange is a risk factor for squamous cell carcinoma of the mouth. They do so by generally relating that there have been reported cases where squamous cell carcinoma, to include of the neck and head, has been associated with exposure to toxic carcinogens, to include Agent Orange. Dr. F.M. opined that there have been reported cases of squamous cell carcinoma of the head and neck associated with Agent Orange exposure in the past. Dr. King opined that Agent Orange is a carcinogen. He indicated that any carcinogen can cause, or contribute to, any cancer. Based on this general conclusion, he opined that the Veteran’s exposure to Agent Orange more likely than not caused his oral cancer. Considered together, the Board finds that the May 2016 VA medical opinion, the December 2017 IME opinion, and the July 2020 VA addendum opinion weigh against a nexus and outweigh any probative value from the opinions from Drs. J.M., Z.S., F.M., and C.K. The Board finds these opinions more probative because of the depth of their rationale and discussion of specific medical literature. The appellant believes the Veteran’s oral squamous cell carcinoma is related to an in-service injury, event, or disease. The appellant is not competent to provide a nexus opinion regarding this issue. The issue is medically complex, as it requires knowledge of the interaction between multiple organ systems in the body, anatomical relationships, and pathology. Therefore, it is outside the competence of the Veteran and the appellant in this case because the record does not show that they have the medical training or credentials to make such a determination. Jandreau v. Nicholson, 492 F.3d 1372, 1377 n.4 (Fed. Cir. 2007) (lay persons not competent to diagnose cancer); see also Kahana v. Shinseki, 24. Vet. App. 428 (2011). Consequently, the Board gives more probative weight to the VA and IME opinions of record. The representative contends that the May 2016 and December 2017 opinions are inadequate with respect to the Veteran’s oral cancer. He contends that the May 2016 VA examiner and December 2017 IME expert relied on inaccurate or inconclusive medical articles and studies to support the conclusion that there is no association between Agent Orange exposure and the development of oral cancer. He contends that the May 2016 examiner focused on smoking and alcohol as major risk factors, and neglected to adequate consider whether the Veteran’s exposure to Agent Orange could also be a risk factor. The Board finds this characterization of the medical opinion is incorrect. The examiner did consider whether Agent Orange could be a risk factor and discussed the favorable medical opinions of record that highlighted such a possibility. The examiner noted that those opinions did not refer to any medical literature supporting their assertions and indicated that several well-regarded medical journals did not even mention Agent Orange as a risk factor. Thus, the examiner did consider Agent Orange as a risk factor; however, he simply reached a conclusion that does not support the appellant’s claim. The representative argues that the IME expert, in discussing a medical study concerning a positive association between Agent Orange and head and neck cancer, did not sufficiently support his negative opinion because he relied on an inconclusive study. Thus, he contends that the study did not constitute positive evidence against the possibility that the Veteran’s oral cancer was related to Agent Orange exposure. The Board does not find this argument persuasive. The expert did not rely on the referenced study, but rather addressed the study as possible positive evidence of a nexus in this case. He noted the potential bias identified by the authors of the study and defects in the construction of the study, e.g., it did not adjust for other risk factors such as smoking and alcohol use. Given these defects, the IME expert concluded that it is less likely the Veteran’s oral squamous cell carcinoma was related to his herbicide exposure, and more likely that it was related to the Veteran’s known smoking and alcohol use. In this regard, the appellant still bears the burden of establishing all elements of a claim for service connection, including the nexus element. Fagan v. Shinseki, 573 F.3d 1282, 1287 (Fed. Cir. 2009). Finally, the representative contends that the July 2020 opinion did not adequately review and consider the December 2017 IME opinion and February 2020 opinion from Dr. C.K. The Board does not find this argument persuasive. The law imposes no reasons-or-bases requirement on examiners, and examiners have no requirement to comment on every favorable piece of evidence in the claims file. Monzingo v. Shinseki, 26 Vet. App. 97, 105-06 (2012); Acevedo v. Shinseki, 25 Vet. App. 286, 293 (2012). The examiner was provided with a copy of the claims file and he indicated that he reviewed the pertinent evidence of record, which would include those opinions. In sum, the evidence shows the Veteran has a current oral squamous cell carcinoma disability and that he is presumed to have been exposed to herbicide agents, to include Agent Orange, during his deployment to the Republic of Vietnam during the Vietnam War. However, the weight of the evidence is against a nexus between the Veteran’s oral squamous cell carcinoma and his exposure to Agent Orange. The evidence is not in equipoise and there is no reasonable doubt to be resolved. As the evidence does not show the Veteran’s oral cancer was incurred in, or is otherwise associated with, active service, a nexus has not been established. Service connection for oral squamous cell carcinoma is not warranted. As service connection for this disease has not been established, service connection for the cause of the Veteran’s death is not warranted either. 2. Entitlement to service connection for basal cell and squamous cell carcinoma of the skin, claimed as due to exposure to herbicide agents, for accrued benefits purposes The appellant seeks service connection for basal cell and squamous cell carcinoma of the skin. She contends that the Veteran’s skin cancer is due to exposure to herbicide agents. This issue has been recharacterized to more aptly reflect the condition at issue and clearly distinguish between the Veteran’s oral carcinoma and the carcinoma that affected his skin. Service connection may be granted for disability resulting from disease or injury incurred in or aggravated by active service. 38 U.S.C. §§ 1110, 1131, 5107; 38 C.F.R. § 3.303. The three-element test for service connection requires evidence of: (1) a current disability; (2) in-service incurrence or aggravation of a disease or injury; and (3) a causal relationship between the current disability and the in-service disease or injury. Shedden v. Principi, 381 F.3d 1163, 1166 -67 (Fed. Cir. 2004). The Veteran’s is presumed to have been exposed to an herbicide agent such as Agent Orange. Squamous cell carcinoma and basal cell carcinoma are not chronic diseases under 38 C.F.R. § 3.309 (a) associated with exposure to herbicide agents. Even if service connection is not warranted on a presumptive basis, if exposure to herbicide agents is presumed, the effects of that exposure must be considered on a direct basis. Combee v. Brown, 34 F.3d 1039 (Fed. Cir. 1994). The question for the Board is whether the Veteran had a current disability that began during service or is at least as likely as not related to an in-service injury, event, or disease. Records show that the claimant was treated for skin cancer, both basal cell carcinoma and squamous cell carcinoma, since about 1996. The evidence shows the Veteran had a squamous cell carcinoma excised from his forehead in July 2006. The July 2020 VA examiner found that the Veteran’s skin cancer is separate from his oral cancer. The Board observes that the May 2016 VA opinion, December 2017 IME report, and the private opinions by Drs. J.M., Z.S., F.M., and C.K. focused on squamous cell carcinoma of the mouth. As noted by the July 2019 memorandum decision with respect to the May 2016 VA opinion, these opinions do not address the Veteran’s skin cancer. As a result, the Board will disregard these opinions in its evaluation of the Veteran’s skin cancer. In July 2020, a VA examiner reviewed the claims file and offered an opinion regarding the Veteran’s basal cell and squamous cell carcinoma of the skin. He opined that it is less likely than not the Veteran’s cutaneous carcinomas are related to Agent Orange exposure or service. He explained that the major risk factor for skin cancers is usually UV exposure from the sun. He noted that cancers typically occur in fair-skinned individuals at sun exposed areas, such as the forehead lesion that the claimant had in 2006. He also explained that medical studies for basal cell and squamous cell carcinomas found no difference between exposure to Agent Orange and non-exposure. Thus, he concluded it is less likely than not the Veteran’s cutaneous squamous cell and basal cell carcinomas are related to service, including Agent Orange exposure. The Board concludes that, while the Veteran had a current diagnosis of cutaneous basal and squamous cell carcinoma, and evidence shows that exposure to Agent Orange occurred, the preponderance of the evidence weighs against finding that the Veteran’s diagnosis of squamous cell and basal cell carcinoma of the skin began during service or is otherwise related to an in-service injury, event, or disease. The July 2020 VA examiner opined that the Veteran’s skin cancer is not at least as likely as not related to an in-service injury, event, or disease, including Agent Orange exposure. The examiner explained that UV exposure is the main risk factor, and that medical studies did not show a difference between exposure to Agent Orange and non-exposure to Agent Orange. The examiner’s opinion is probative, because it is based on an accurate medical history and provides an explanation that contains clear conclusions and supporting data. Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 304 (2008). The representative contends that the July 2020 VA opinion with respect to skin cancer is not adequate. He asserts that the opinion’s conclusion that Agent Orange exposure is not a risk factor for squamous cell and basal cell carcinomas of the skin is inaccurate, and that the examiner did not provide any meaningful discussion as to how the medical study that was cited applies to this specific case. The Board does not find this argument persuasive. An opinion is adequate where it is based upon consideration of a veteran’s prior medical history and examinations and describes the disability in sufficient detail so that the Board may make a fully informed decision. D’Aries, 22 Vet. App. at 104. The opinion was adequate because the expert rendered a clear medical judgment and supported that judgment with clear rationale. Monzingo, 26 Vet. App. at 107. Specifically, the examiner highlighted that relevant medical literature found no difference between exposure to Agent Orange and non-exposure for basal cell and squamous cell carcinomas of the skin. The appellant believes the Veteran’s skin cancer is related to an in-service injury, event, or disease but she is not competent to do so. Again, a layperson without medical training and experience is not competent to provide an opinion as to the etiology on cancer because this is a complex medical determination. Consequently, the Board gives more probative weight to the July 2020 VA opinion. In sum, following a review of the evidence of record, the Board finds that the preponderance of the evidence is against the claim. As such, there is no reasonable doubt to be resolved, and the claim of entitlement to service connection for basal cell or squamous cell carcinoma of the skin is denied. D. JOHNSON Veterans Law Judge Board of Veterans’ Appeals Attorney for the Board D. Lauritzen, Associate Counsel The Board’s decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.