A comparison of the localization of rectal carcinomas according to the general rules of the Japanese classification of colorectal carcinoma (JCCRC) and Western guidelines

Purpose The aim of this study was to compare the localization of rectal cancers as classified according to the general rules of the Japanese classification of colorectal carcinoma (JCCRC) and also according to the European Society for Medical Oncology (ESMO) and the National Comprehensive Cancer Network (NCCN) guidelines, which are based on rigid endoscopic measurements. Methods The medical records of patients scheduled to receive curative surgery for histologically proven rectal adenocarcinoma during 2009–2015 were investigated ( n = 230). Rigid proctoscopy was performed in patients with rectal cancer located in the upper (Ra) or lower (Rb) division using double-contrast barium enema. Results The median values of height from the anal verge were 7.5 cm (range 2–12) and 3 cm (0–9.5) on rigid proctoscopy for cancers assigned as Ra and Rb, respectively. All 159 cancers at Ra or Rb were located within 12 cm from the anal verge by rigid proctoscopy, while only 79.7% of Ra or 82.1% of Rb cancers were located in the mid (5.1–10 cm) or low (≤5 cm) rectum, respectively. Conclusion Ra and Rb cancers are deemed to be rectal cancers according to NCCN guidelines, but these classifications are not interchangeable with mid- and low-rectal cancers, respectively, according to the ESMO guidelines.