Rectal cancer staging: Correlation between the evaluation with radial echoendoscope and rigid linear probe

BACKGROUND AND OBJECTIVES: The National Cancer Institute estimated 40,340 new cases of rectal cancer in the United States in 2013. The correct staging of rectal cancer is fundamental for appropriate treatment of this disease. Transrectal ultrasound is considered one of the best methods for locoregional staging of rectal tumors, both radial echoendoscope and rigid linear probes are used to perform these procedures. The objective of this study is to evaluate the correlation between radial echoendoscopy and rigid linear endosonography for staging rectal cancer. PATIENTS AND METHODS: A prospective analysis of 48 patients who underwent both, radial echoendoscopy and rigid linear endosonography, between April 2009 and May 2011, was done. Patients were staged according to the degree of tumor invasion (T) and lymph node involvement (N), as classified by the American Joint Committee on Cancer. Anatomopathological staging of surgical specimen was the gold standard for discordant evaluations. The analysis of concordance was made using Kappa index. RESULTS: The general Kappa index for T staging was 0.827, with general P < 0.001 (confidence interval [CI]: 95% 0.627-1). The general Kappa index for N staging was 0.423, with general P < 0.001 (CI: 95% 0.214-0.632). CONCLUSION: The agreement between methods for T staging was almost perfect, with a worse outcome for T2, but still with substantial agreement. The findings may indicate equivalence in the diagnostic value of both flexible and rigid devices. For lymph node staging, there was moderate agreement between the methods.