The Veteran's cause of death due to lung cancer is not related to service, and his service-connected disabilities did not contribute substantially or materially to cause death. The appeal for eligibility for substitution in a February 2017 claim for service connection for melanoma is remanded.

The Veteran's cause of death, metastatic lung cancer, was found to be related to service and caused or contributed substantially to the Veteran's death. The Board granted entitlement to service connection for the Veteran's cause of death.

The Veteran's cause of death was metastatic neuroendocrine carcinoma, which is presumed to be related to his exposure to herbicides during service in Vietnam. The Board found that the Veteran's service-connected metastatic lung cancer contributed substantially or materially to his death.,Entitlement to DIC under 38 U.S.C. § 1318 was dismissed as moot due to the grant of service connection for the cause of the Veteran's death.

The Board has remanded the case due to insufficient evidence regarding whether the Veteran's esophageal cancer, which caused his death, was related to his service exposure to herbicide agents.

The Veteran's cause of death was not caused by a service-connected disability, and the cancer did not manifest to a compensable degree within one year after discharge from service. The Veteran was rated 100% disabled for his mental health disorder less than two years before his death, but he was not rated continuously for ten years preceding death or continuously since release from active duty for at least five years preceding death.