Utility of endoscopic ultrasound-guided fine-needle aspiration in the diagnosis and staging of colorectal carcinoma

Abstract

The objective of this study is to assess the utility of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in the diagnosis and staging of colorectal cancer. The study includes patients who underwent EUS-FNA at our institution for staging of colorectal carcinoma or for evaluation peri-rectal masses or distal metastases from August 2000 to November 2010. We assessed the frequency with which EUS-FNA procedure confirms the diagnosis of malignancy and the percent of cases in which it modifies staging of colorectal carcinoma. Using histology as a reference standard, we also assessed the diagnostic performance. We identified 79 cases of EUS-FNA from 77 patients, mean (SD) age of 60 (12.5), 44 males. Twenty-seven (34%) aspirates were from patients with primary rectal/peri-rectal masses, 15 (19%) were from patients with suspected regional lymph node metastasis, and 37 (47%) were cases of suspected of distal metastasis. All lesions were clinically suspicious for primary or metastatic colorectal carcinoma. On cytologic examinations, 43 (54%) cases were confirmed as malignant, 6 (8%) were benign neoplasms, 4 (5%) were suspicious for malignant neoplasm, 2 (3%) showed atypical cells, and the rest 24 (30%) were negative for neoplasms. Fourteen of 27 (52%) of the local rectal masses were confirmed as colorectal carcinoma. Eleven of 15 (73%) regional lymph nodes were positive for metastasis-all, but two of these metastases, were of colorectal origin. Twenty of 37(54%) distal lesions were metastatic neoplasms and 15 of those were colorectal in origin. Diagnosis of primary colorectal carcinoma was confirmed in 52% of the clinically suspicious primary lesions and in 42% regional or distal metastatic lesions. Using histology as a reference standard in 27 of 79 (29%) cases, we calculated an overall sensitivity, specificity, and positive and negative predictive values (C.I) of EUS-FNA of 89% (74-100%), 79% (50-100%) 89% (74-100%), and 79% (51-100%). EUS-FNA is useful for assessing primary and metastatic colorectal lesion. This technique improves staging of suspected nodal or distant metastases.

Keywords: colorectal cancer; fine-needle aspiration; staging of rectal disease.