99mTc has been used to label many anti-CEA antibodies (e.g. BW431/26, IMMU-4 and 88BV59) and used in clinical studies for the detection of colorectal, breast and lung cancer (Barzen et al. 1992; Baum et al. 1989; Behr et al. 1995; Fraile et al. 1991; Gonzalez et al. 1991; Kairemo et al. 1993; Lacic et al. 1999; Lind et al. 1989; Lind et al. 1991a; Lind et al. 1991b; Oriuchi et al. 1995; Patt et al. 1994; Serafini et al. 1998; Sirisriro et al. 1996; Stomper et al. 1995; Takenoshita et al. 1995). The gene discussed is CEACAM5; the disease is lung cancer.