42 C.F.R. § 81.25
For claims including two or more primary cancers, DOL will use NIOSH-IREP to calculate the estimated probability of causation for each cancer individually. Then DOL will perform the following calculation using the probability of causation estimates produced by NIOSH-IREP:
Equation 1
Calculate: 1-[{1-PC1} × {1-PC2}×. . . × {1-PCn}] = PCtotal,
where PC1is the probability of causation for one of the primary cancers identified in the claim, PC2is the probability of causation for a second primary cancer identified in the claim, and PCnis the probability of causation for the nth primary cancer identified in the claim. PCtotalis the probability that at least one of the primary cancers (cancers 1 through "n") was caused by the radiation dose estimated for the claim when Equation 1 is evaluated based on the joint distribution of PC1, . . ., PCn.3 DOL will use the probability of causation value calculated for PCtotalto adjudicate the claim.
3 Evaluating Equation 1 based on the individual upper 99th percentiles of PC1, . . ., PCnapproximates the upper 99th percentile of PCtotalwhenever PC1, . . ., PCnare highly related, e.g., when a common dose-reconstruction is the only non-negligible source of uncertainty in the individual PCi's. However, this approximation can overestimate it if other sources of uncertainty contribute independently to the PC1, . . ., PCn, whereas treating the joint distribution as fully independent could substantially underestimate the upper 99th percentile of PCtotalwhenever the individual PCi's are positively correlated.
42 C.F.R. §81.25