Tumor cells circulate in the blood, but it is unusual to find cancer cells
on a routine peripheral smear. The term carcinocythemia is used to describe
this phenomenon. Four patients have been reported previously with small ce
ll lung cancer and carcinocythemia. A fifth case is described in this artic
le. These patients presented with advanced disease and had generalized lymp
hadenopathy and liver involvement; 3 had splenic metastases. All of these p
atients experienced rapid clinical deterioration. Death occurred 3 days to
2 weeks from the time carcinocythemia was detected. The presence of small c
ell carcinocythemia can be one of the manifestations of end-stage disease a
nd is associated with an extremely poor prognosis.