Pathological Evaluation of Horizontal Extension in Non-Muscle Invasive Bladder Cancer Resected using TURBO (Transurethral Resection of Bladder Tumor in One Piece) Technique

Using TURBO technique, we accurately evaluated horizontal extension of non-muscle invasive bladder tumors in relation to clinical and pathological parameters. Non-muscle invasive bladder tumors sized less than 20 mm were resected with an approximately 5-mm margin from the stalk using the TURBO technique. Specimens from 52 cases were pathologically examined to determine the amount of horizontal extension, which was analyzed for correlations with several clinical and pathological parameters, including tumor size and stalk diameter. Twenty cases (38.5%) were found to have horizontal extension of cancer, ranging from 0.6 to 6.1 mm (median 2.8 mm). The existence of horizontal extension was significantly more often associated with primary (17/32: 53.1%) than recurrent (3/20; 15.0%) tumors (p=0.014) and likely to be associated with high grade tumors (p=0.053). Tumors with a stalk greater than 2 mm were more significantly associated with horizontal extension (18/37; 48.6%) in contrast to those with a smaller stalk (2/15; 13.3%) (p=0.040), though no such trend was observed in terms of tumor size (p=0.202). Furthermore, horizontal extension length was significantly correlated with stalk diameter/tumor size ratio (r=0.5060), but not with tumor size (r= -0.2203) or stalk diameter (r=0.1847). Our findings showed that resection with a wider surgical margin are required in cases with a tumor stalk diameter thicker than 2 mm, especially in those with a stalk diameter/tumor size ratio of 0.4 or more. Our results are considered to be the first useful evidence showing the need for horizontally complete resection of non-muscle invasive bladder cancer.