Antigen-Directed Cancer Surgery for Primary Colorectal Cancer: 15-Year Survival Analysis

Stephen P. Povoski MD, Ioannis S. Hatzaras MD, MPH, Cathy M. Mojzisik RN, MS, Mark W. Arnold MD, George H. Hinkle RPh, MS, Charles L. Hitchcock MD, PhD, Donn C. Young PhD, Edward W. Martin Jr. MD
Colorectal Cancer
Volume 19, Issue 1 / January , 2011

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Abstract

Background

Tumor-associated glycoprotein-72 (TAG-72) is a mucin-like high-molecular-weight glycosylated protein complex overexpressed by many adenocarcinomas. Antigen-directed cancer surgery using radiolabeled anti-TAG-72 murine monoclonal antibodies (muMAbs) has been previously investigated for colorectal cancer. Survival analysis of primary colorectal cancer patients with a minimum of 15-year follow-up after antigen-directed cancer surgery was performed to assess the impact of complete surgical resection of all detectable radiolabeled anti-TAG-72 muMAb.

Methods

Survival analysis was performed on 92 patients (study group) with primary colorectal cancer (July 1990 to August 1995) treated with antigen-directed cancer surgery using ¹²⁵I-labeled anti-TAG-72 muMAb. The study group was subdivided into those with no detectable TAG-72 antigen-bearing tissues (TAG-72 negative, N = 33) and those with persistent detectable TAG-72 antigen-bearing tissues (TAG-72 positive, N = 59) at completion of surgery. Comparisons were made with a control group (546 patients) from the same time period.

Results

Study group and control group were demographically similar, as were TAG-72-negative subgroup and TAG-72-positive subgroup. TAG-72-negative subgroup had significantly improved median survival (8.8 versus 2.5 years; P = 0.005) and time-dependent survival (45.4% versus 22.0% at 10 years; P = 0.002 and 39.4% versus 20.3% at 15 years; P = 0.003) compared with TAG-72-positive subgroup. TAG-72 positivity was as an independent predictor of long-term mortality risk, when controlled for pathologic stage of disease.

Conclusions

Absence of detectable TAG-72 antigen within the surgical field at completion of antigen-directed cancer surgery for primary colorectal cancer is of significant prognostic value, conferring a long-term survival advantage to those in whom complete surgical removal of all tissues with detectable radiolabeled anti-TAG-72 muMAb was accomplished.

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