Late relapses in acute promyelocytic leukaemia.

From January 1988 to December 1997, among 53 acute promyelocytic leukaemia patients in 1st complete remission (CR) after 5 years from diagnosis, we observed 5 late relapses (9.4%) after 60, 61, 71, 101 and 155 months from diagnosis; 3 of those late relapses (7.7%) occurred among 39 patients previously treated with all-trans-retinoic acid. An involvement of the mastoid occurred in 3/5 patients (60%), compared with 2/32 patients (6.3%) at an early relapse (p < 0.02). As to the treatment of the late relapse, 1 patient received all-trans-retinoic acid alone followed by allogeneic transplantation and 4 patients were treated according to the GIMEMA 0191 protocol. All patients achieved a 2nd CR and are still alive: 4 in the 2nd molecular CR after 6, 33, 34 and 115 months; 1 relapsed after 15 months and is now in the 3rd CR. In conclusion, a late relapse occurred in a sizeable fraction of acute promyelocytic leukaemia patients: the high rate of ear involvement might be explained considering the ear as a 'disease sanctuary'.