Changes in serum immunosuppressive acidic protein following surgery in patients with renal carcinoma

Serum immunosuppressive acidic protein (IAP) was measured serially in 69 patients with renal carcinoma who were treated surgically and followed up for more than 6 months after surgery. Elevated IAP levels > 600 micrograms/ml were seen in 8 of 52 patients without evidence of recurrence and in 5 of 10 patients prior to clinical evidence of recurrence but in whom recurrence did eventually develop. The positive rate of IAP levels > 600 micrograms/ml in recurrent cases was significantly higher than in non-recurrent ones. In 7 patients with distant metastases, IAP levels rose to > 500 micrograms/ml in 3 of 5 patients whose disease progressed despite therapy; levels fell to < 600 micrograms/ml in 2 patients who responded to therapy. The data suggest that recurrence should be suspected in patients with IAP levels > 600 micrograms/ml, as these changes appear to correlate with the response of metastases to therapy.