{"data":{"id":"us/42-cfr-81.23","jurisdiction":"us","citation":"42 CFR 81.23","heading":"Guidelines for cancers for which primary site is unknown.","body":"(a) In claims for which the primary cancer site cannot be determined, but a site of metastasis is known, DOL will calculate probability of causation estimates for various likely primary sites. Table 1 of this paragraph (a) indicates the primary cancer site(s) DOL will use in NIOSH-IREP when the primary cancer site is unknown.\nTable 1 to Paragraph (a)\nPrimary cancers (ICD-10-CM codes) for which probability of causation is to be calculated, if only a secondary cancer site is known. “M” indicates cancer site should be used for males only, and “F” indicates the cancer site should be used for females only.\nSecondary cancer (ICD-10-CM code) ICD-10-CM code of likely primary cancers\nLymph nodes of head, face and neck (C77.0) C01, C02, C07(M), C08(M), C09(M), C10(M), C14(F), C32(M), C33, C34, C43, C44, C50(F), C73(F), D03.\nIntrathoracic lymph nodes (C77.1) C15(M), C33, C34, C50(F).\nIntra-abdominal lymph nodes (C77.2) C15(M), C16(M), C18, C25(F), C33, C34, C50(F), C53(F), C61(M), C64, C65, C66, C68, C82(F), C84(F) (excluding C84.6, C84.7), C85(F), C86(F) (excluding C86.5, C86.6), C91.4(F), C96(F).\nLymph nodes of axilla and upper limb (C77.3) C33, C34, C43, C50(F) , D03.\nInguinal and lower limb lymph nodes (C77.4) C19(M), C20(M), C21(M), C33, C34, C43, C44(F), C60(M), C63(M), D03.\nIntrapelvic lymph nodes (C77.5) C18(M), C19(F), C20(F), C21(F), C33(M), C34(M), C53(F), C54(F), C61(M), C67.\nLymph nodes of multiple sites (C77.8) C15(M), C16(M), C18(M), C33, C34, C50(F).\nLymph nodes, site unspecified (C77.9) C15(M), C16, C18, C33, C34, C43, C50(F), C61(M), D03.\nLung (C78.0) C18, C33, C34, C43(M), C50(F), C61(M), C67(M), C64, C65, C66, C68, D03(M).\nMediastinum (C78.1) C15(M), C33, C34, C50(F).\nPleura (C78.2) C15(M), C18(M), C33, C34, C50(F), C56(F), C57(F), C61(M), C64(M), C65(M), C66(M), C68(M).\nOther respiratory organs (C78.3) C15, C18(M), C32, C33, C34, C44(M), C50(F), C61(M), C73(F).\nSmall intestine, including duodenum (C78.4) C17, C18, C25, C33, C34, C49, C43(M), C50(F), C56(F), C57(F), C64(M), C65(M), C66(M), C68(M), D03(M).\nLarge intestine and rectum (C78.5) C18, C19, C20, C21, C33, C34, C50(F), C56(F), C57(F), C61(M).\nRetroperitoneum and peritoneum (C78.6) C16, C18, C19(M), C20(M), C21(M), C25, C33(M), C34(M), C49, C50(F), C54(F), C56(F), C57(F).\nLiver, specified as secondary (C78.7) C16(M), C18, C19(M), C20(M), C21(M), C25, C33, C34, C50(F).\nOther digestive organs (C78.8) C15(M), C16, C18, C25, C33, C34, C50(F), C61(M).\nKidney (C79.0) C18, C33, C34, C50(F), C53(F), C61(M), C67, C64, C65, C66, C68, C82(F), C84(F) (excluding C84.6, C84.7), C85(F), C86(F) (excluding C86.5, C86.6), C91.4(F), C96(F).\nOther urinary organs (C79.1) C18, C50(F), C53(F), C56(F), C57(F), C61(M), C67, C64(F), C65(F), C66(F), C68(F).\nSkin (C79.2) C18, C33, C34, C49(M), C43, C44(M), C50(F), C64(M), C65(M), C66(M), C68(M), D03.\nBrain and spinal cord (C79.3) C33, C34, C43(M), C50(F), D03(M).\nOther parts of nervous system (C79.4) C33, C34, C43(M), C50(F), C61(M), C82, C84 (excluding C84.6, C84.7), C85, C86 (excluding C86.5, C86.6), C91.4, C96, D03(M).\nBone and bone marrow (C79.5) C33, C34, C50(F), C61(M).\nOvary (C79.6) C18(F), C50(F), C56(F), C57(F).\nAdrenal gland (C79.7) C18(F), C33, C34, C50(F).\nOther specified sites (C79.8) C18, C33, C34, C43(M), C50(F), C56(F), C57(F), C61(M), C67(M), D03(M).\nUnspecified sites (C79.9) C18, C33, C34, C43(M), C50(F), C56(F), C57(F), C61(M), C67(M), D03(M).\nCarcinoid tumor of distant lymph nodes (C7B.01) C15(M), C16, C18, C33, C34, C43, C50(F),C61(M), D03.\nCarcinoid tumor of liver (C7B.02) C16(M), C18, C19(M), C20(M), C21(M), C25, C33, C34, C50(F).\nCarcinoid tumor of bone (C7B.03) C33, C34, C50(F), C61(M).\nCarcinoid tumor of peritoneum (C7B.04) C16, C18, C19(M), C20(M), C21(M), C25, C33(M), C34(M), C49, C50(F), C54(F), C56(F), C57(F).\nMerkel cell carcinoma (C7B.1) C18, C33, C34, C49(M), C43, C44(M), C50(F), C64(M), C65(M), C66(M), C68(M), D03.\n(b) DOL will select the site producing the highest estimate for probability of causation to adjudicate the claim.","path":["Title 42—Public Health","CHAPTER I—PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES","SUBCHAPTER G—OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES","PART 81—GUIDELINES FOR DETERMINING PROBABILITY OF CAUSATION UNDER THE ENERGY EMPLOYEES OCCUPATIONAL ILLNESS COMPENSATION PROGRAM ACT OF 2000","Subpart E—Guidelines To Estimate Probability of Causation"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-42.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:11Z","sha256":"6cbec7da7f608f17185910b9c3586cf3bc6738b35786b78873ba1bd0a527ad7f","source_id":"us-cfr","stale":true,"prev":"us/42-cfr-81.22","next":"us/42-cfr-81.24"},"notice":"GroundRules: Original legal text. Not legal advice."}