Effect of radioimmunoscintigraphy on the management of recurrent colorectal cancer.

Abstract

Radioimmunoscintigraphy (RIS) is being used increasingly as a new investigation in the diagnosis of recurrent colorectal cancer. This study assessed the efficacy of 99mTc-radiolabelled PR1A3 scanning in a cohort of patients with possible recurrent colorectal cancer and the effects of scan interpretation on subsequent clinical management. The scans and case notes of patients scanned over a 3-year period were reviewed. Forty-seven scans in 40 patients were available for analysis. In 39 instances in which scan interpretation could be verified accurately, sensitivity for recurrent colorectal cancer was 22 of 23 (96 per cent), specificity for recurrent colorectal cancer was eight of 16 (50 per cent), positive predictive value for recurrence was 22 of 30 (73 per cent) and negative predictive value for recurrence was eight of nine (89 per cent). In 16 of the 40 patients, scan interpretation strengthened a management decision or altered management. This was beneficial to ten patients and possibly detrimental to six. This study demonstrated that RIS is sensitive in the detection of recurrent colorectal cancer and benefited the patient in one-quarter of cases. For the majority of patients, accurate detection of recurrent disease cannot be followed by curative therapy, but there is an important subgroup of patients in whom RIS alters management beneficially. However, a randomized prospective study is needed to confirm this.