RADIOIMMUNOSCINTIGRAPHY WITH TC-99M LABELED MONOCLONAL-ANTIBODY 170H.82 IN SUSPECTED PRIMARY, RECURRENT, OR METASTATIC BREAST-CANCER

Radioimmunoscintigraphy (RIS) with Tc-99m labeled 170H.82, an intact m urine monoclonal antibody (MAb) was performed in 27 patients with susp ected primary, recurrent, or metastatic breast cancer. For radioimmuno imaging the authors used a double-headed, high-resolution gamma camera . The lesions defected by RIS were evaluated by histopathology, and fo r metastatic disease by CT, MRI, and bone scan. If the evaluation was made lesion by lesion, RIS with Tc-99m MAb 170H.82 showed 23 true-posi tive results, 3 false-negative results, 9 true-negative results, 3 fal se-positive results for primary and recurrent disease; sensitivity was 88% and specificity was 75%. In patients with distant metastases, det ection rate was 67% (12 true-positive results and 6 false-negative res ults). All patients had normal baseline values for human anti-mouse an tibodies (HAMA) and 6 weeks after RIS with 2 mg MAb, only 2 of 23 pati ents had developed a HAMA response (9%). No adverse effects were obser ved, The authors' clinical experience shows that RIS with MAb 170H.82 is a valuable additional method for detecting breast cancer, especiall y in patients with uncertain primaries or scar tissue after breast con serving treatment in which differential diagnosis is very difficult.