Primary liver cancer and exposure to solvents

A case-referent study was done on the possible association between primary liver cancer (ICD 155.0) and occupational exposures. In all, 374 cases were reported to the Finnish Cancer Registry in 1979 and 1980. After the exclusion of wrong diagnoses, nonrespondents and cases for whom the primary site was uncertain, 126 cases (64 men and 62 women) remained. Each case was matched for sex, age (+/- 5 years), vital status and geographical district with two cases of coronary infarction selected from hospital records without any knowledge of occupational history. Nonrespondence (38%) reduced the number to 175 referents (82 men and 92 women). A questionnaire on former employment and tasks was mailed to living subjects (6 + 6) and to the next of kin of deceased patients. An industrial hygienist then evaluated the exposure history blindly and, whenever necessary, contacted the workplace or the next of kin for more details. Only exposures commencing 10 years or more before diagnosis were considered. Altogether six female cases but no referent had been exposed to solvents. One had been exposed to chlorinated solvents in dry cleaning and two others had used both carbon tetrachloride and aromatic and aliphatic solvents. Three cases had been exposed to mixtures of aliphatic and aromatic solvents, but not chlorinated hydrocarbons. By contrast, the men did not differ with regard to exposure to solvents. Two cases and five referents were classified as having been exposed to solvent mixtures. The present results are hypothesis generating only, and the excess solvent exposure found for women must be confirmed in other studies before any conclusions can be drawn.