Routine baseline serum carcinoembryonic antigen as a negative predictor of peritoneal metastasis in colorectal malignancies: a cost-effective tool in South India

ABSTRACT

Background: Colorectal cancer, a formidable health problem worldwide has upto 8% synchronous peritoneal carcinomatosis. As only diagnostic laparoscopy can identify them, in countries with economic burden, selection of patients for laparoscopy is ideal. Our aim is to evaluate whether the baseline Carcinoembryonic antigen (CEA) is a good selection tool.Methods: A retrospective study of 125 patients, who were diagnosed to have colorectal malignancy (any stage) and underwent elective surgery at our institution from 2012 till 2019 were included. The baseline serum CEA was compared with the intraoperative findings. The threshold levels of serum CEA compared were 6.5 and 100 ng/dl. The sensitivity, specificity, positive predictive value and negative predictive value for both thresholds were compared in 3 categories of patients, namely peritoneal metastasis (9 cases), metastasis to other organs (36 cases) and cases with no metastasis either in peritoneum or other organs (85 cases). The results were analysed using SPSS software.Results: The mean age was 65, sex ratio (malefemale) was 7253. The sensitivity, specificity, positive predictive value, negative predictive value (NPV) for CEA threshold of 6.5 ng/dl was 44.44%, 60.34%, 8% and 93.33% for category 1. For CEA threshold of 100 ng/dl, it was 33.33%, 97.41%, 50% and 94.95% for category 1. NPV was 96.55% for category 3 (the highest value).Conclusions: If the baseline CEA levels are less than 100 ng/dl,   96.55% of cases will not require a diagnostic laparoscopy. This hopefully will cut down the cost of unnecessary diagnostic laparoscopies, and reduce the morbidity of unnecessary laparotomies.