Serum levels of a cytokeratin 19 fragment, Cyfra 21-1, were measured u
sing an immunoradiometric assay in 33 women before initial treatment a
nd in 8 women with recurrent tumor. The serum level of Cyfra 21-1 was
significantly increased in women with tumors of advanced stage (FIGO)
and those with recurrence. The incidence of positivity for Cyfra 21-1
tended to increase with tumor spread. Compared with squamous cell carc
inoma (SCC) antigen, the sensitivity of Cyfra 21-1 was comparable to t
hat of SCC antigen. The serum level of Cyfra 21-1 and that of SCC anti
gen showed a positive correlation. While the use of the serum Cyfra 21
-1 level may be limited in cervical cancer by its relatively low sensi
tivity, a combination assay of Cyfra 21-1 and SCC antigen may be usefu
l in the diagnosis and follow-up of patients with cervical squamous ce
ll carcinoma.