nonmuscleinvasive

Nonmuscle invasive describes a disease that is confined to the mucosa or submucosa and does not invade the muscularis propria. In urology, the term is most often applied to nonmuscle-invasive bladder cancer (NMIBC), which encompasses tumors staged as Ta, T1, or carcinoma in situ. Ta tumors are noninvasive papillary lesions limited to the urothelium; T1 tumors invade the lamina propria but not the detrusor muscle; carcinomas in situ are flat, high-grade lesions confined to the urothelium.

Management typically starts with transurethral resection of the bladder tumor (TURBT) for diagnosis and removal, followed by adjuvant intravesical therapy such as bacillus Calmette-Guérin (BCG) or chemotherapy (e.g., mitomycin C). NMIBC has a relatively high risk of recurrence and requires long-term surveillance with periodic cystoscopy and urine tests. Risk stratification into low, intermediate, and high risk guides treatment intensity and surveillance intervals. High-risk NMIBC includes high-grade T1 disease, CIS, multifocal or large tumors, or concurrent hydronephrosis, and may warrant more aggressive therapy including induction BCG and consideration of early cystectomy in select cases.

Compared with muscle-invasive disease, NMIBC generally has a more favorable prognosis at presentation, but progression to muscle-invasive disease can occur in a significant minority. The term nonmuscle invasive can also apply to other organ systems where cancer is confined to mucosa or submucosa, but in common clinical practice it refers to NMIBC.