Relationship between maximum size of the primary tumor and serum cea with preoperative clinical staging in rectal cancer patients

Background: Patients in resource limited setup have limited access to preoperative Magnetic Resonance Imaging (MRI). The study aims to assess the relationship between maximum size of the primary tumor and baseline serum CEA with AJCC primary tumor stage (T) and nodal staging (N). Methods: A retrospective analysis of 67 rectal cancer patients, treated at a tertiary care centre was undertaken. Patients were evaluated for clinical profile and treatment details. Ordinal regression was employed to assess relationship between maximum size of the primary tumor, serum CEA and AJCC ‘T’ and ‘N’ staging. Results: Nearly 49% (n=33) patients presented in stage III, 66% (n=44) patients underwent abdominal perineal resection (APR), 46% (n=31) patients received neoadjuvant chemoradiotherapy while 21% (n=14) received neoadjuvant chemotherapy. The mean size of primary tumor (cm) and serum CEA (ng/ml) for the study participants was 5.47 (2-9) and 16.98 (0-112) respectively. For every one unit increase in maximum size of the primary tumor, there is a 0.437 times increase in the odds of the tumor upstaging (p=0.003). If the serum CEA increases by one unit, there is 0.011 times increase in the odds of number of positive nodes (p=0.049). Conclusions: Maximum size of the primary tumor and serum CEA were significant predictor of ‘T’ stage and ‘N’ stage respectively. In resource limited settings where affordability and accessibility to MRI limits accurate preoperative rectal cancer staging, maximum size of the primary tumor and serum CEA can complement CT findings for clinical staging and neoadjuvant treatment decisions.