Abnormalities of chromosome 16 in AML include del(16q), inv(16) and t(
16;16). These three groups have been categorized together and have bee
n associated with high complete remission (CR) and survival rates foll
owing Ara-C-based chemotherapy. We have reviewed the 63 AML or MDS pat
ients with an abnormality of chromosome 16 treated at MD Anderson Canc
er Center (MDACC) over the past 18 years. Marked differences in surviv
al and remission duration (RD) were noted between the inv(16) or t(16;
16) patients and those with del(16q), whose outcome was no better than
other M4 AML or MDS patients treated during the same period. Other di
fferences characterizing del(16q) included a lack of CNS relapses, low
er incidences of eosinophilia and M4 FAB subtype. Half the inv(16) pat
ients had additional karyotypic abnormalities. The overall survival an
d remission duration for those patients were no different from those f
or patients with inv(16) alone, although the probability of remaining
in first CR at 2 years was higher in the inv(16) alone group. There wa
s no difference in overall survival for the 45 patients who received H
DAC vs those who did not. The incidence of CNS relapse was, however, m
arkedly reduced for the HDAC patients. Eosinophilia did not correlate
with improved survival. We conclude that del(16q) confers a different
prognosis from inv(16) and t(16;16) and for the purposes of prognostic
ation or treatment recommendations should no longer be categorized wit
h them. Additional karyotypic changes however, which accompany inv(16)
in 50% of cases do not influence the overall outcome compared to pati
ents with inv(16) alone.