DISSENTING OPINION BY
Judge LEAVITT.Respectfully, I dissent. The initial decision of the WCJ properly denied the claim petition. The Board ordered a remand on the theory that Claimant was entitled to a presumption that the cancer present in his lung was caused by his employment as a firefighter. However, the Board erred in invoking the statutory presumption because Claimant was found to have suffered from adrenal cancer, which happened to spread to his lungs, and not from a primary lung cancer.
The relevant facts are as follows. Claimant worked for the City of Philadelphia as a firefighter from 1965 to 1990, when he retired because of a non-work related knee injury. In May of 1993 he noticed a lump in his skin, over his left breast, and was hospitalized at Rolling Hill Hospital for surgical removal of the tumor. The pathology report concluded that the tumor was cancerous, but it could not pinpoint the source of the cancer because the cells were so poorly differentiated. Additional tests showed a mass in his left lung. He was referred to Fox Chase where he began a regimen of chemotherapy and radiation. On December 6, 1993, Fox Chase biopsied tissue from Claimant’s left lung and concluded that it was a “metastatic adenocarcinoma of unknown primary.” Reproduced Record 109a (R.R.-). A large mass was discovered on his right adrenal gland, but it was not biopsied. He died in April of 1994. Although an autopsy was requested by the hospital, the family denied the request.1 R.R. 224-225a.
Section 301(e) of the Act, 77 P.S. § 413, allows a claimant a presumption that his occupational disease was caused by employment if the disease is a hazard in his occupation or industry. Disease of the heart or lung after four or more years of service as a firefighter is a defined occupational disease. Section 108(o) of the Act, 77 P.S. § 27.1(o). However, Claimant never established that he suffered from a disease of the lung; accordingly, the presumption in Section 301(e) had no application to his claim petition.
Claimant’s only evidence of lung cancer was the opinion of Jonathan Gelfand, M.D., who examined Claimant in January of 1994. His testimony detailed a history of Claimant’s work experience and exposure to smoke and dust, and he discounted Claimant’s long history of cigarette and cigar smoking. Dr. Gelfand was not found credible by the WCJ.2 Notably, Claimant did not produce a pathology report that identified his aggressive cancer as a lung cancer.
By contrast, Employer’s medical experts identified Claimant’s cancer as adrenal cancer, and they were believed by the WCJ. The key witness was Giuseppe G. *1266Pietra, M.D., certified in anatomic pathology and a Professor of Pathology at the University of Pennsylvania School of Medicine; his specialty is pulmonary cardiovascular disease. ' He reviewed the testimony of Claimant and Dr. Gelfand; the pathology slides from the biopsy of Claimant’s initial tumor; electomierophotographs made by the Medical College of Pennsylvania; and biopsies taken at the Medical College Hospital and Fox Chase. He conducted his own tests and studies.
Dr. Pietra explained that microscopic examination of pathology material is the only way to establish with any degree of certainty the nature and most likely site of origin of a malignant tumor. R.R. 145a. The microscopic samples established that Claimant’s cancer was a carcinoma as opposed to a sarcoma. Dr. Pietra then looked for features that might suggest that the cancerous cell had its origin in the lung, but he could not find those features. R.R. 147a. For example, tests for keratin, a substance present in tumor arising from lung and skin cells, were negative. Dr. Pietra then used an electromicroscope and did tests in his own lab on the tumor; these studies3 identified the site of origin as the adrenal gland, rather than the lung or skin. Dr. Pietra’s conclusion was based upon peculiar structures found in the mitochondria and in the endoplasmic reticulum of Claimant’s cancer cells that are found only in adrenal cells. R.R. 148a-149a. He then explained that adrenal carcinomas are rare, aggressive and difficult to discover; they first present in an advanced stage as multiple tumor nodules in the lung, skin and bone. R.R. 150a. By contrast, lung cancer tends to spread to the brain and liver. R.R. 151a. Dr. Pietra opined that Claimant’s cancer originated in his adrenal gland4 and was not causally related to his work as a firefighter. Indeed, the medical literature does not relate adrenal cancer to any particular occupation.
Theodore Rodman, M.D., board certified in internal medicine, also testified for Employer; he specializes in pulmonary medicine. Dr. Rodman reviewed Claimant’s medical .records prior to his final illness, such as the 1989 X-rays done when Claimant was hospitalized for a tibia fracture, in addition to all the records, biopsies, X-rays and CAT scans generated by Claimant’s fight with cancer. R.R. 195a. Dr. Rod-man explained that a well-differentiated cancer cell is easy to identify, but in Claimant’s case a convential microscopic histo-logic examination could not identify the organ where the tumor arose. R.R. 196a-198a. Noting that Dr. Pietra is a world-class pulmonary pathologist, Dr. Rodman was persuaded by Dr. Pietra’s analysis that the site of origin was Claimant’s adrenal gland. Dr. Rodman testified that the medical literature does not indicate that adrenal carcinoma is occupationally related *1267to firefighting or to any particular occupation.
Dr. Rodman further observed that Claimant did not suffer an underlying pulmonary problem resulting from firefighting that would predispose him to a primary lung tumor. There was no evidence of interstitial pulmonary fibrosis or asbestosis in any of the Claimant’s many X-rays and CAT scans. He concluded that Claimant did not suffer an occupational disease. R.R. 215a-217a.
The Board remanded for a determination of whether the testimony of Dr. Pietra and Dr. Rodman was sufficient to rebut the presumption5 that Claimant’s “lung cancer” was caused by firefighting. This was error. It was Claimant’s burden to establish an occupational disease, and he did not. The WCJ did not credit Dr. Gelfand’s testimony that Claimant had lung cancer, and the only biopsy from Claimant’s lung tissue showed that it was a metastatic tumor, ie., from another site. In short, the record was devoid of any evidence to support a finding that Claimant suffered lung cancer, which was a necessary precondition to the presumption established in Section 301(e) of the Act, 77 P.S. § 418.
I would reverse the Board and affirm the initial decision of the WCJ.
. The lawyer for Claimant asserted that an autopsy would have yielded definitive results. R.R. 225a.
. The record indicates several possibilities for this finding: Dr. Gelfand admitted that he routinely gives depositions for Claimant's counsel (R.R. 107a); Dr. Gelfand did not review the medical records from Fox Chase (R.R. 109a-110a); and the pulmonary function tests performed in Dr. Gelfand’s office yielded anomalous results (R.R. 221a-223a).
. These studies were done on the initial tumor sample from the chest well, which was the only sample large enough for Dr. Pietra's tests.
. The second WCJ characterized Dr. Pietra’s testimony as not ruling out a primary lung cancer. A single statement should not be taken out of context as defeating the rest of the testimony. Lewis v. Workmen’s Compensation Appeal Board, 508 Pa. 360, 366, 498 A.2d 800, 803 (1985). The following exchange occurred during cross-examination:
Q. As I understand your testimony, it is not possible for. you to determine the origin of the cancer in George Billing; is that correct?
A. No, that’s not what I said. I said that based on the examination of the pathology, the microscopic features of the tumor present in the left breast indicated it was from the adrenal rather than from any other site.
R.R. 153a. In short, Dr. Pietra’s testimony was unequivocal and cannot be characterized as not ruling out a primary lung tumor.
. The presumption applies to causation of the occupational disease not to the diagnosis or establishment of the occupational disease. Accordingly, if Claimant had established a primaiy lung cancer, then the statutory presumption would have supported a finding that the disease was caused by firefighting and not by his history of cigar and cigarette smoking.