Citation Nr: 1303922 Decision Date: 02/04/13 Archive Date: 02/08/13 DOCKET NO. 05-33 791 ) DATE ) ) On appeal from the Department of Veterans Affairs Regional Office in St. Petersburg, Florida THE ISSUE Entitlement to service connection for colon cancer, to include as due to exposure to ionizing radiation and/or toxic chemicals. REPRESENTATION Appellant represented by: Disabled American Veterans WITNESS AT HEARING ON APPEAL Appellant ATTORNEY FOR THE BOARD Jennifer Hwa, Counsel INTRODUCTION The Veteran served on active duty from January 1959 to January 1961. This matter comes before the Board of Veterans' Appeals (Board) on appeal from a November 2004 rating decision by the Department of Veterans Affairs (VA) Regional Office (RO) in St. Petersburg, Florida, which, in pertinent part, denied the Veteran's claim for service connection for colon cancer. In July 2007, the Veteran testified at a travel board hearing before the undersigned Veterans Law Judge. A copy of the transcript for this hearing has been associated with the claims file. The Board remanded this claim for additional development in October 2007. In January 2012, the Board requested a Veterans Health Administration (VHA) opinion, and the VHA opinion was obtained in March 2012. The Board again remanded the claim for additional development in May 2012. The Board notes that, in addition to the paper claims file, there is a paperless, electronic (Virtual VA) claims file associated with the Veteran's claim. A review of the documents in such file reveals that certain documents, including VA medical records dated from August 2003 to August 2012, are potentially relevant to the issue on appeal. Thus, the Board has considered these electronic records in its adjudication of the Veteran's case. FINDING OF FACT Colon cancer was first diagnosed many years after the Veteran's discharge from service, the most probative evidence indicates that the condition is not likely related to radiation or toxic chemical exposure in service, and there is no competent evidence that such disability is otherwise related to the Veteran's military service. CONCLUSION OF LAW The requirements for establishing service connection for colon cancer have not been met. 38 U.S.C.A. §§ 1101, 1110, 1112, 5107 (West 2002 & Supp. 2012); 38 C.F.R. §§ 3.303, 3.307, 3.309, 3.311 (2012). REASONS AND BASES FOR FINDING AND CONCLUSION Veterans Claims Assistance Act of 2000 The Veterans Claims Assistance Act of 2000 (VCAA), Pub. L. No. 106-475, 114 Stat. 2096 (Nov. 9, 2000) (codified at 38 U.S.C.A. §§ 5100, 5102, 5103, 5103A, 5106, 5107, and 5126 (West 2002 & Supp. 2012)) redefined VA's duty to assist a claimant in the development of a claim. VA regulations for the implementation of the VCAA were codified as amended at 38 C.F.R. §§ 3.102, 3.156(a), 3.159, and 3.326(a) (2012). The notice requirements of the VCAA require VA to notify the claimant of any evidence that is necessary to substantiate the claim, as well as the evidence VA will attempt to obtain and which evidence he is responsible for providing. 38 C.F.R. § 3.159(b) (2012). The requirements apply to all five elements of a service connection claim: veteran status, existence of a disability, a connection between a veteran's service and the disability, degree of disability, and effective date of the disability. Dingess/Hartman v. Nicholson, 19 Vet. App. 473 (2006). VCAA notice must be provided to a claimant before the initial unfavorable decision on a claim for VA benefits by the agency of original jurisdiction (in this case, the RO). Id.; see also Pelegrini v. Principi, 18 Vet. App. 112 (2004). However, the VCAA notice requirements may be satisfied if any errors in the timing or content of such notice are not prejudicial to the claimant. See Pelegrini, 18 Vet. App. at 121. In this case, in a May 2004 letter issued prior to the decision on appeal, the Veteran was provided notice regarding what information and evidence is needed to substantiate his claim for service connection, as well as what information and evidence must be submitted by the Veteran and what information and evidence will be obtained by VA. An April 2006 letter advised the Veteran of how disability evaluations and effective dates are assigned, and the type of evidence which impacts those determinations. The case was last readjudicated in September 2012. The record also reflects that VA has made reasonable efforts to obtain relevant records adequately identified by the Veteran. Specifically, the information and evidence that have been associated with the claims file include the Veteran's service treatment records and service personnel records, VA and private treatment records, a medical opinion from the VA Director of Radiation and Physical Exposures, VA examination reports, a VHA opinion, and hearing testimony. Additionally, the prior remand instructions were substantially complied with. Instructions pertinent to the claim being decided included obtaining the Veteran's service personnel records, obtaining updated VA medical records, requesting the Veteran's radiation dose information and obtaining a radiation dose estimate, scheduling the Veteran for a VA examination, and issuing a supplemental statement of the case. In response, the RO/AMC obtained the Veteran's service personnel records and all updated VA medical records. The RO/AMC attempted to obtain the Veteran's radiation dose information, and in January 2010, the RO/AMC received a radiation dose estimate with nexus opinion. The RO/AMC also scheduled the Veteran for a June 2010 VA examination with a January 2011 VA addendum opinion, and the Board subsequently requested a VHA opinion in January 2012 in order to supplement the January 2011 VA medical opinion. Finally, the RO/AMC issued a supplemental statement of the case in September 2012 that considered all of the previous relevant evidence. Accordingly, the Board finds that there has been substantial compliance with the prior remand instructions and no further action is necessary. See D'Aries v. Peake, 22 Vet. App. 97 (2008) (holding that only substantial, and not strict, compliance with the terms of a Board remand is required pursuant to Stegall v. West, 11 Vet. App. 268 (1998)). As discussed above, the VCAA provisions have been considered and complied with. The Veteran was notified and aware of the evidence needed to substantiate his claim, the avenues through which he might obtain such evidence, and the allocation of responsibilities between himself and VA in obtaining such evidence. The Veteran was an active participant in the claims process by providing evidence and argument. Thus, he was provided with a meaningful opportunity to participate in the claims process and has done so. Any error in the sequence of events or content of the notices is not shown to have any effect on the case or to cause injury to the Veteran. Therefore, any such error is harmless and does not prohibit consideration of this matter on the merits. See Dingess, supra; see also ATD Corp. v. Lydall, Inc., 159 F.3d 534, 549 (Fed. Cir. 1998). Legal Criteria Service connection may be established for a disability resulting from disease or injury incurred in or aggravated by service. 38 U.S.C.A. §§ 1110, 1131 (West 2002); 38 C.F.R. § 3.303 (2012). Evidence of continuity of symptomatology from the time of service until the present is required where the chronicity of a condition manifested during service either has not been established or might reasonably be questioned. 38 C.F.R. § 3.303(b). Regulations also provide that service connection may be granted for any disease diagnosed after discharge, when all of the evidence, including that pertinent to service, establishes that the disability was incurred in service. 38 C.F.R. § 3.303(d). Moreover, where a veteran served continuously for ninety (90) days or more during a period of war, or during peacetime service after December 31, 1946, and malignant tumors become manifest to a degree of 10 percent within one year from the date of termination of such service, such disease shall be presumed to have been incurred or aggravated in service, even though there is no evidence of such disease during the period of service. This presumption is rebuttable by affirmative evidence to the contrary. 38 U.S.C.A. §§ 1101, 1131, 1137 (West 2002); 38 C.F.R. §§ 3.307, 3.309 (2012). Generally, in order to prove service connection, there must be competent, credible evidence of (1) a current disability, (2) in-service incurrence or aggravation of an injury or disease, and (3) a nexus, or link, between the current disability and the in-service disease or injury. See, e.g., Davidson v. Shinseki, 581 F.3d 1313 (Fed. Cir. 2009); Pond v. West, 12 Vet. App. 341 (1999). Service connection for conditions claimed to be due to exposure to ionizing radiation in service can be established in several different ways. See Davis v. Brown, 10 Vet. App. 209, 211 (1997); Rucker v. Brown, 10 Vet. App. 67, 71 (1997). First, there are diseases that are presumptively service-connected in radiation-exposed veterans under 38 U.S.C.A. § 1112(c) and 38 C.F.R. § 3.309(d). Second, service connection can be established under 38 C.F.R. § 3.303(d) with the assistance of the procedural advantages prescribed in 38 C.F.R. § 3.311, if the condition at issue is a radiogenic disease. Third, direct service connection can be established under 38 C.F.R. § 3.303(d) by showing that the disease was incurred during or aggravated by service without regard to the statutory presumptions. See Combee v. Brown, 34 F.3d 1039, 1043-44 (Fed. Cir. 1994). The fact that the requirements of a presumptive regulation are not met does not in and of itself preclude a claimant from establishing service connection by way of proof of actual direct causation. Id. Finally, for certain chronic diseases, service connection may be assigned on a presumptive basis if the condition is manifested to a compensable degree within a prescribed period, generally one year, following discharge from service. 38 C.F.R. § 3.309(a). A "radiation-exposed veteran" is defined by 38 C.F.R. § 3.309(d)(3) as a veteran who while serving on active duty or on active duty for training or inactive duty training, participated in a radiation-risk activity. "Radiation-risk activity" is defined to mean onsite participation in a test involving the atmospheric detonation of a nuclear device; the occupation of Hiroshima, Japan or Nagasaki, Japan by United States forces during the period beginning on August 6, 1945, and ending on July 1, 1946; or internment as a prisoner of war (or service on active duty in Japan immediately following such internment) during World War II which resulted in an opportunity for exposure to ionizing radiation comparable to that of the United States occupational forces in Hiroshima or Nagasaki during the period from August 6, 1945 through July 1, 1946. 38 C.F.R. § 3.309(d)(i), (ii) (2012). Diseases presumptively service-connected for radiation-exposed veterans under the provisions of 38 U.S.C.A. § 1112(c) and 38 C.F.R. § 3.309(d)(2) are: leukemia (other than chronic lymphocytic leukemia), cancer of the thyroid, cancer of the breast, cancer of the pharynx, cancer of the esophagus, cancer of the stomach, cancer of the small intestine, cancer of the pancreas, multiple myeloma, lymphomas (except Hodgkin's disease), cancer of the bile ducts, cancer of the gall bladder, primary liver cancer (except if cirrhosis or hepatitis B is indicated), cancer of the salivary glands, cancer of the urinary tract; bronchiolo-alveolar carcinoma; cancer of the bone; cancer of the brain; cancer of the colon; cancer of the lung; and cancer of the ovary. 38 U.S.C.A. § 1112(c)(2); 38 C.F.R. § 3.309(d). If a claimant does not qualify as a "radiation-exposed veteran" under 38 C.F.R. § 3.309(d)(3) and/or does not suffer from one the presumptive conditions listed in 38 C.F.R. § 3.309(d)(2), the veteran may still benefit from the special development procedures provided in 38 C.F.R. § 3.311 if the veteran suffers from a radiogenic disease and claims exposure to ionizing radiation in service. Under 38 C.F.R. § 3.311, "radiogenic disease" means a disease that may be induced by ionizing radiation and shall include the following: (i) all forms of leukemia except chronic lymphatic (lymphocytic) leukemia; (ii) thyroid cancer; (iii) breast cancer; (iv) lung cancer; (v) bone cancer; (vi) liver cancer; (vii) skin cancer; (viii) esophageal cancer; (ix) stomach cancer; (x) colon cancer; (xi) pancreatic cancer; (xii) kidney cancer; (xiii) urinary bladder cancer; (xiv) salivary gland cancer; (xv) multiple myeloma; (xvi) posterior subcapsular cataracts; (xvii) non-malignant thyroid nodular disease; (xviii) ovarian cancer; (xix) parathyroid adenoma; (xx) tumors of the brain and central nervous system; (xxi) cancer of the rectum; (xxii) lymphomas other than Hodgkin's disease; (xxiii) prostate cancer; and (xxiv) any other cancer. 38 C.F.R. § 3.311(b)(2). Under the special development procedures in § 3.311(a), dose data will be requested from the Department of Defense in claims based upon participation in atmospheric nuclear testing, and claims based upon participation in the American occupation of Hiroshima or Nagasaki, Japan, prior to July 1, 1946. 38 C.F.R. § 3.311(a)(2) (2012). Background The Board has reviewed all of the evidence in the Veteran's claims file. Although the Board has an obligation to provide adequate reasons and bases supporting this decision, there is no requirement that the evidence submitted by the Veteran or obtained on his behalf be discussed in detail. Rather, the Board's analysis below will focus specifically on what evidence is needed to substantiate the claim and what the evidence in the claims file shows, or fails to show, with respect to the claim. See Gonzales v. West, 218 F.3d 1378, 1380-81 (Fed. Cir. 2000) and Timberlake v. Gober, 14 Vet. App. 122, 128-30 (2000). During the Veteran's period of active service, he was assigned to the First U.S. Army Escort Detachment 1327, Seneca Ordnance Depot, in Romulus, New York. The Veteran has submitted documents showing that during his assignment at the Seneca Ordnance Depot, the facility had contained a number of contaminants, including chlorinated solvents, radioactive isotopes, heavy metals, and petroleum hydrocarbons. The evidence suggests that the Veteran may have been exposed to these contaminants, but the extent of the exposure is unable to be determined based on the available data. However, service treatment records are negative for any complaints, diagnoses, or treatment for colon cancer. On separation examination in November 1960, the Veteran made no complaints regarding his colon, and his colon was found to be within normal limits. Post-service VA and private medical records dated from April 2003 to August 2012 reflect that the Veteran received intermittent treatment for colon cancer. The evidence indicates that the Veteran was first diagnosed with colon cancer in April 2003, when a colonoscopy revealed a malignant lesion of the sigmoid colon. He underwent a sigmoid colon resection in May 2003, which indicated the presence of moderately differentiated adenocarcinoma with invasion into the perimuscular adipose tissue with metastases to 5/6 pericolic lymph nodes. The Veteran testified before the Board at a travel board hearing in July 2007. Testimony revealed, in pertinent part, that he served as an escort guard while stationed at Seneca County in service. The Veteran reported that the facility set off a lot of explosions which contaminated the ground. He indicated that the surgeon who operated on his colon had informed him that the colon cancer was slow-moving and that it was possible that the cancer had been due to the contamination in service. In an August 2007 letter, the private surgeon who had operated on the Veteran's sigmoid colon reported that he had treated the Veteran since April 2003. He indicated that after reviewing with the Veteran "his history of exposure during his stay at Romulus NY, 1959-1960," it was "not unreasonable to draw a connection between his exposure to toxic materials and the development of colon cancer." The surgeon also noted that the Veteran did not have any other pre-existing condition or family history of colon cancer. In July 2009, the RO/AMC requested that the Under Secretary for Health prepare a dose assessment, to the extent feasible, and subsequently determine whether the Veteran's colon cancer was due to exposure to radiation while assigned to the Seneca Ordnance Depot. In January 2010, the VA Director of Radiation and Physical Exposures reviewed the evidence and utilized the Interactive Radioepidemiological Program (IREP) of the National Institute for Occupational Safety and Health to estimate the likelihood that exposure to ionizing radiation caused the Veteran's colon cancer. She acknowledged the August 2007 statement from the Veteran's private surgeon which indicated that the Veteran's colon cancer was due to his exposure to ionizing radiation at Seneca Ordnance Depot. However, she found that the surgeon's statement was based on a description of the Veteran's activities and not on a known radiation dose. The Director also noted that the Veteran's DD Form 1141, Record of Occupational Exposure to Ionizing Radiation, was not available in the service records, nor was there a radiation dose of record for the Veteran from the U.S. Army. She explained that the usual reason for no occupational monitoring was the fact that the Veteran was not likely to be exposed to more than 0.5 rem per year, which was the threshold at which monitoring was required. Despite this, the Director afforded the Veteran the benefit of the doubt and assigned him the maximum allowed annual occupational dose of 5 rem per year for each of the calendar years he was assigned to Seneca Ordnance Depot. The IREP calculated that the probability of causation for colon cancer was only 26.57 percent. The Director therefore opined that it was unlikely that the Veteran's colon cancer was caused by exposure to ionizing radiation while in military service. In a January 2010 memorandum, the Director of Compensation and Pension Service (C&P) reviewed the Chief Public Health and Environmental Hazards Officer's January 2010 dose estimate and opinion. He noted that the Veteran had been 19 years old when assigned to Seneca Ordnance Depot and that colon cancer had been diagnosed 53 years after exposure to ionizing radiation while stationed at Seneca Ordnance Depot. He also pointed out that the Veteran's post-service employment included being a foreman for a factory that made storm windows. Moreover, the Veteran had a history of smoking until he quit in the mid-1960s, but a family history of cancer or leukemia was not identified. The Director of C&P opined that based on the January 2010 dose estimate and opinion as well as a review of the evidence in its entirety, there was no reasonable possibility that the Veteran's colon cancer was the result of his occupational exposure to ionizing radiation during service. On VA examination in June 2010, the Veteran reported being an escort guard at Seneca North Army Depot for 1.5 years. He stated that his date of onset of colon cancer was in 2003 when he had bright red blood in his stools. He underwent a colonoscopy and colectomy. He subsequently received chemotherapy treatment for 6 months. The Veteran received yearly colonoscopies, but there had been no recurrences of cancer. Examination revealed that the Veteran's overall general health was good. He was diagnosed with colon cancer status post colectomy and chemotherapy with no recurrence. Regarding whether the Veteran's colon cancer was due to his period of active service, the VA examiner indicated that she had not reviewed the Veteran's service treatment records, VA medical records, or private medical records. Instead, she noted that she had reviewed medical literature. She opined that the Veteran's colon cancer was as least as likely as not due to his period of service because the Veteran had presented literature that low levels of radioactive contamination were found at Seneca Army Depot where he served. She also stated that colon cancer was a presumptive illness due to ionizing radiation. However, the VA examiner also opined that the Veteran's colon cancer was less likely as not due to his period of service. She cited a report entitled "Public Summary and Context Contaminated Water Supplies at Camp LeJeune Assessing Potential Health Effects," which had concluded that there was inadequate/insufficient evidence to determine whether there was an association between colon cancer and the toxic chemicals trichloroethylene and dichloroethylene. The examiner therefore concluded that there was inadequate/insufficient evidence to determine whether an association existed between colon cancer and toxic chemicals. She stated that the evidence from available studies was of insufficient quality, quantity, or consistency to permit a conclusion regarding the existence of an association between exposure to a specific agent and a specific health outcome in humans. As the June 2010 VA examiner did not appear to have reviewed the Veteran's claims file in rendering her opinions, the claims file was returned to her in January 2011 for an addendum opinion. In her review of the Veteran's claims file, the June 2010 examiner noted that the Veteran's private surgeon did not provide any supporting data to substantiate his August 2007 medical opinion that the Veteran's colon cancer was due to exposure to toxic materials. She also reported that her expertise in oncology included treatment of established malignancies and not the epidemiology of the same. However, she opined that the supporting documents provided in refutation of the Veteran's claim as well as the 40 year hiatus between any exposures and the development of colon cancer made the conclusion that the Veteran's cancer was at least as likely due to ionizing radiation an untenable one. The June 2010 VA examiner provided an incomplete opinion regarding whether the Veteran's colon cancer was related to exposure to toxic chemicals. Additionally, the June 2010 VA examiner freely admitted in her January 2011 addendum opinion that her expertise in oncology included only the treatment of established malignancies and not the epidemiology of such malignancies. Therefore, in January 2012, the Board requested a VHA opinion from an oncologist to address these issues. In March 2012, a VA oncologist reviewed the Veteran's entire claims file. He noted that the Veteran was 63 years old when he was first diagnosed with colon cancer and that he was 19-20 years old when he was stationed at the Seneca Ordnance Depot and potentially exposed to toxic chemicals. The oncologist stated that since the Veteran did not have any family history of colon cancer, the major risk factor for him was his age, as it had been found that over 90 percent of sporadic colon cancers were diagnosed after age 50. The oncologist also indicated that the other major risk factor was diet, with a high intake of red and processed meats and that of highly refined grains and starches being associated with an increased risk of colon cancer. Smoking and alcohol were also noted to have been associated with the increased risk of colon cancer. The oncologist stated that although it had been documented in one of the notes that the Veteran had quit smoking in the 1960s and thus had minimal smoking history, the nature of the Veteran's diet and alcohol use prior to the diagnosis of colon cancer was unknown. After reviewing the Veteran's claims file and medical literature, the VA oncologist found that there was no convincing evidence that linked potential chemical exposure or background radiation to increased risk of sporadic colon cancer. He explained that if the Veteran had been diagnosed at a much earlier age (in the absence of family history) or had had multiple colon cancers diagnosed over a period of years suggesting potential field cancerization of the bowel lining, then it would have been reasonable to attribute the Veteran's colon cancer to some environmental factor. However, since the Veteran was diagnosed with colon cancer when he was in his 60's and had only one cancerous lesion, the oncologist opined that it was very likely that the Veteran had had a sporadic cancer that just "happened." He concluded that it was very difficult to link the Veteran's diagnosis to potential exposure to chemicals and/or radiation that may have occurred over 40 years ago. Analysis Regarding entitlement to service connection on a presumptive basis for radiation-exposed veterans, the Board notes that colon cancer is a disease that is presumptively service-connected for radiation-exposed veterans under the provisions of 38 U.S.C.A. § 1112(c) and 38 C.F.R. § 3.309(d)(2). However, the Veteran's period of active service did not include participation in a "radiation-risk activity" as defined under 38 C.F.R. § 3.309(d)(ii), and therefore he does not meet the criteria of being a "radiation-exposed veteran" as required under 38 C.F.R. § 3.309(d)(i) for entitlement to presumptive service connection. Thus, service connection is not warranted on a presumptive basis for the Veteran's colon cancer. The Board reiterates that there is no evidence of colon cancer during service, nor has the Veteran suggested that this cancer occurred during the year following discharge from service. Indeed, the evidence indicates this disability was first diagnosed by biopsy in 2003. An evaluation of the probative value of medical opinion evidence is based on the medical expert's personal examination of the patient, the examiner's knowledge and skill in analyzing the data, and the medical conclusion reached. The credibility and weight to be attached to such opinions are within the province of the Board as adjudicators. Guerrieri v. Brown, 4 Vet. App. 467 (1993); Gabrielson v. Brown, 7 Vet. App. 36 (1994). Greater weight may be placed on one physician's opinion over another depending on factors such as reasoning employed by the physicians and whether or not and the extent to which they reviewed prior clinical records and other evidence. Gabrielson v. Brown, 7 Vet. App. 36 (1994). The probative value of a medical opinion is generally based on the scope of the examination or review, as well as the relative merits of the expert's qualifications and analytical findings, and the probative weight of a medical opinion may be reduced if the examiner fails to explain the basis for an opinion. Sklar v. Brown, 5 Vet. App. 140 (1993). The Board acknowledges that a private physician opined in an August 2007 letter that there was a connection between the Veteran's exposure to toxic materials and the development of his colon cancer. However, the physician did not appear to have reviewed the entire claims file in rendering his opinion. Prejean v. West, 13 Vet. App. 444 (2000) (factors for assessing the probative value of a medical opinion include the physician's access to the claims folder and the Veteran's history, and the thoroughness and detail of the opinion). Additionally, he provided no rationale or supporting data for the statement. If the examiner does not provide a rationale for the opinion, that weighs against the probative value of the opinion. Sklar v. Brown, 5 Vet. App. 140 (1993). Regarding the June 2010 VA examiner's opinions with January 2011 addendum, the Board affords these opinions little, if any, probative weight. The June 2010 VA opinions that the Veteran's colon cancer was due to his ionizing radiation exposure but that there was insufficient evidence to determine whether there was an association between his toxic chemical exposure and colon cancer were rendered without the VA examiner having reviewed the claims file. Prejean v. West, 13 Vet. App. 444. Indeed, the examiner's opinion that the Veteran's colon cancer was a presumptive disease for ionizing radiation did not take into account the fact that the Veteran did not participate in any radiation-risk activities during service. As for the examiner's opinion that there was insufficient evidence to determine whether there was an association between the Veteran's toxic chemical exposure and colon cancer, this equivocal or inconclusive opinion amounts to nonevidence, neither for nor against the Veteran's claim, and is afforded little probative weight. Moreover, although the VA examiner subsequently reviewed the Veteran's claims file in January 2011 and opined that the Veteran's colon cancer was not due to ionizing radiation exposure, she indicated that her expertise in oncology included only the treatment of established malignancies and not the epidemiology of such malignancies. As the VA examiner does not have expertise in the epidemiology of colon cancer, her opinions are afforded no probative weight. See Black v. Brown, 10 Vet. App. 297, 284 (1997) (in evaluating the probative value of medical statements, the Board looks at factors such as the individual knowledge and skill in analyzing the medical data). By contrast, the March 2012 VA oncologist thoroughly reviewed the claims file and provided adequate reasoning and bases for the opinion that it was less likely than not that the Veteran's colon cancer was caused by his period of service. Specifically, he explained that if the Veteran had been diagnosed with colon cancer at a much earlier age (in the absence of family history) or had had multiple colon cancers diagnosed over a period of years suggesting potential field cancerization of the bowel lining, then it would have been reasonable to attribute the Veteran's colon cancer to some environmental factor. However, since the Veteran was diagnosed with colon cancer when he was in his 60's and had only one cancerous lesion, the oncologist opined that it was very likely that the Veteran had had a sporadic cancer that just "happened," and it was very difficult to link the Veteran's diagnosis to potential exposure to chemicals and/or radiation that may have occurred over 40 years ago. The Board finds the VA oncologist's opinion to be highly probative and credible because he is a medical specialist in the field of oncology. See Black v. Brown, 10 Vet. App. 297, 284. For these reasons, the March 2012 opinion by the VA oncologist is afforded greater probative value than the August 2007 opinion from the private physician as well as the June 2010 and January 2011 opinions from the VA examiner. In accordance with 38 C.F.R. § 3.311, the RO/AMC conducted appropriate development regarding the Veteran's colon cancer, as it is considered a radiogenic disease. The RO/AMC's development included a request to the National Personnel Records Center and the Surgeon General of the Army for the Veteran's DD Form 1141, Record of Occupational Exposure to Ionizing Radiation. Although this document was not available, the RO/AMC still requested from the Under Secretary for Health a dose assessment and opinion as to whether such radiation exposure resulted in the Veteran's colon cancer. In January 2010, the VA Director of Radiation and Physical Exposures, a medical doctor, reviewed the evidence, provided a dose assessment based on the available information, and utilized IREP to estimate the likelihood that exposure to ionizing radiation caused the Veteran's colon cancer. Thereafter, the Director determined that it was unlikely that the Veteran's colon cancer could be attributed to his radiation exposure in service. While the Veteran contends that his colon cancer is due to his exposure to ionizing radiation and/or toxic chemicals, he is not shown to possess any specialized training in the medical field to provide a competent medical opinion on this point. See Jandreau v. Nicholson, 492 F.3d 1372, 1376-77 (Fed. Cir. 2007) (noting general competence to testify as to symptoms but not to provide medical diagnosis). To the extent that the Veteran himself believes that his current colon cancer is due to service, to include exposure to ionizing radiation and/or toxic chemicals, as a lay person, his opinion as to the etiology of his current colon cancer is not competent medical evidence, as such question requires medical expertise to determine. Id. Thus, the Board finds the medical opinions of record to be of greater probative value than the Veteran's lay contentions. Moreover, whether the symptoms the Veteran reportedly experienced in service or following service are in any way related to his current colon cancer is a matter that also requires medical expertise to determine. See Clyburn v. West, 12 Vet. App. 296, 301 (1999) ("Although the veteran is competent to testify to the pain he has experienced since his tour in the Persian Gulf, he is not competent to testify to the fact that what he experienced in service and since service is the same condition he is currently diagnosed with."). As noted above, the most probative medical opinions are against a finding that the current colon cancer is related to service. In sum, the Board finds that the preponderance of the evidence indicates that the Veteran's colon cancer was not present in service, and there is no competent and credible evidence indicating his colon cancer was manifested to a compensable degree within a year following discharge from service. Likewise, the weight of the competent and probative evidence does not show this disability is related to the Veteran's service, to include his exposure to ionizing radiation and toxic chemicals therein. Accordingly, service connection for colon cancer is not warranted on any basis. In reaching the conclusions above, the Board has considered the applicability of the benefit of the doubt doctrine. However, as the preponderance of the evidence is against the Veteran's claim, that doctrine is not applicable in the instant appeal. See 38 U.S.C.A. § 5107(b); Ortiz v. Principi, 274 F.3d 1361, 1364 (Fed. Cir. 2001); Gilbert v. Derwinski, 1 Vet. App. 49, 55-57 (1990). ORDER Entitlement to service connection for colon cancer, to include as due to exposure to ionizing radiation and/or toxic chemicals, is denied. ____________________________________________ WAYNE M. BRAEUER Veterans Law Judge, Board of Veterans' Appeals Department of Veterans Affairs