CHATTANOOGA, Tenn.—Cancer was the most common cause of long-term absence from work for the fourth consecutive year in 2004, according to disability insurer UnumProvident Corp.

Based on data from claims submitted in 2004 to the Chattanooga, Tenn.-based insurer, cancer accounted for 12% of disability claims that involve an absence from work of more than 90 days.

Rounding out the top-five causes of long-term absence were pregnancy complications, 10%; joint, muscle and connective-tissue diseases, 10%; back injuries, 9%; and cardiovascular disease, 8%.

The top-five causes of short-term work absence were pregnancy, 21%; nonback injuries, 9%; digestive and intestinal diseases, 8%; back injuries, 7%; and reproductive and urinary system disease, 7%.

UnumProvident based the rankings on its private database, which tracks 26.8 million covered lives and about 178,000 employer policyholders.