Some 444 people are thought to have died from the side effects of the lung cancer drug Iressa, which Japan approved in July 2002, the Health, Labor and Welfare Ministry said Wednesday.
Japan was the first country to approve the use of the drug, which was developed by AstraZeneca PLC of Britain.
The ministry added, however, that this figure may not be accurate, as some deaths originally linked to Iressa were later traced to other causes.
To date, the ministry has received reports on a total of 1,151 cases of Iressa side effects. In May 2003, the ministry announced the number of deaths linked to Iressa at 246.