Efficacy of narrow band imaging (NBI) in restaging transurethral resection of high-grade non- muscle-invasive bladder cancer
Narrow-band imaging (NBI) is an optical high-resolution enhancement technology which filters the bandwith of withe light output to blue(415 nm) and green(540 nm).The narrow bandwidth of light is strongly absorbed by haemoglobin and penetrates only the surface of tissue, increasing the visibility of capillaries and other delicate tissue surface structures. Through this, the contrast between mucosal surfaces and microvascular structures can be enhanced. Many studies have dimostrated that NBI cystoscopy improves the detection rate of bladder carcinomas , especially for flat cancerous lesions as carcinoma in situ(CIS)[1,2]. Few works have assessed the effectiveness of NBI during a second transurethral resection(TUR) for the restaging of high-grade non-muscle-invasive bladder cancer(NMIBC).In this study we have investigated the use of NBI during a second TUR of high-grade NMIBC for the diagnosis of residual tumors.
Methods and results
From January 2012 to December 2013, 39 consecutive patiens (median age 63 years, range 41- 82 years, 32 men and 7 woman)with primary diagnosis of high-grade NMIBC were enrolled in this prospective study. The inclusion criteria for enrolling patients included: primary solitary high-grade NMIBC. The exclusion criteria included: previous history of bladder cancer, previous history of intravesical therapy, presence of muscle invasive bladder cancer,positive urinary cytology. In accord with the international guidelines for the treatment of high-grade NMIBC ,a restaging of tumor was performed after near three weeks from the first TUR.The standard operating procedure of this protocol included a deep resection with white light of the primary resection zone and contemporary excision of macroscopic recurrences or suspicious areas. After we performed a resection of all suspicious areas observed by NBI. Grading was performed in according to WHO 2004 classification. The finding of white light evaluation showed a visible recurrent tumor in one patients(2.6%) at the periphery of the primary lesion.The histological examination was T1 high-grade tumor . The resection of the base of primary areas was positive in two patients(5%). The histological specimen was :one CIS and one Ta high-grade tumor. Eighteen were the suspicious zones resected with white light and two was positive for tumor(11%):one CIS and one Ta low-grade tumor. NBI transurethral resection was performed in 63 suspicious areas and in 9(14%) was positive for tumor: five CIS,two Ta high-grade tumor and two papillary tumor. The two suspicious areas positive for cancer in white light resection was similar to NBI so the overall recurrence rate observed with NBI was of 11%. All the restaging procedures was performed with Olympus NBI video system.
The natural history of high-grade NMIBC is difficult to predict .Factors known to reflect tumor aggressiveness include presence of CIS, early recurrence and failure of BCG induction. The management of high-grade T1 bladder cancer is still controversial. Complete transurethral resection of the tumor, second look and adjuvant intravesical instillation usually recommended and remain the standard of care.
Meticulous follow-up with biopsy of any suspicious lesion may provide early diagnosis of invasive disease. Hidas reported a 6.1 % of progression to muscle- invasive bladder cancer .
In a recent study performed in 894 patients the restaging TUR was the only predictor of recurrence at 5 years with a 44.3% recurrence rate in patients with a single resection compared to 9.6% in those with restaging resection.NBI is a simple procedure that allows accurate detection of abnormal lesions without the use of agents and without controindications for patients .With NBI system the bladder lesions appears dark green o black against the almost white normal mucosa ,whereas with with light these lesions appear red on a pink normal urothelium. Furthemore NBI provides better visualization of lesion by precise delineation of margins that can be useful for the excision site of the tumor.
Several studies have demostrated that NBI is superior to white light for detecting of CIS. Shen reported a sensitivity in detecting CIS of 77.7% for white light and 92.9% for NBI;Tatsugami showed a sensitivity of 89.7% for NBI and 50% for white light.The diagnosis of CIS is particularly important for the control of tumor progression .We have evaluated the efficacy of a second TUR of high-grade NMIBC performed with NBI.Naselli et al reported a 34% of residual/recurrent during a second resection using an extensive protocol with NBI. In this study NBI biopsies increased the dection rate with a overall 13% of residual high-grade cancer.
Similarly to this study we have found a 31% of residual tumor at the second restaging TUR of high-grade NMIBC. CIS was observed in 15% of cases . NBI was positive in the 14% of biopsies and the overall dection rate of NBI resection was of 11%.In particular NBI was useful for increased the diagnosis of CIS with a dection rate of 6%.
In conclusion we believe that restaging of high-grade NMIBC is mandatory for the control of disease and NBI is an effective method for the identification of abnormal lesions especially for CIS.
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