Section 81.21 - Cancers requiring the use of NIOSH-IREP(a) DOL will calculate probability of causation for all cancers using NIOSH-IREP.(b) Carcinoma in situ (ICD-10-CM codes D00-D09), neoplasms of uncertain behavior (ICD-10-CM codes D37-D44 and D48), and neoplasms of unspecified nature (ICD-10-CM code D49) are assumed to be malignant, for purposes of estimating probability of causation.(c) All secondary and unspecified cancers of the lymph node (ICD-10-CM codes C77 and C7B.01) shall be considered secondary cancers (cancers resulting from metastasis of cancer from a primary site). For claims identifying cancers of the lymph node, Table 1 in § 81.23(a) provides guidance for assigning a primary site and calculating probability of causation using NIOSH-IREP. 84 FR 37590 , Aug. 1, 2019