CIS is a surrogate marker of genetic instability and field carcinogenesis in the urothelial mucosa

Abstract

Objective

To investigate whether carcinoma in situ (CIS) lesion could be considered a surrogate marker of urothelium genetic instability and field carcinogenesis or not, we evaluated DNA content, p53 overexpression, and proliferative index (Ki-67 expression) in primary tumor, in tumor-adjacent mucosa, and distant urothelial mucosa with and without presence of CIS.

Patients and methods

A retrospective study in radical cystectomy specimens from 49 patients was carried out. All the lesions present in each cystectomy specimen were studied, including the tumor area and the adjacent mucosa (AM). Whenever possible, the distant mucosa (DM) was also studied. When CIS was detected, this lesion and the surrounding normal mucosa were also studied. The 49 tumor areas included high grade papillary urothelial carcinoma (HGP) in 19 cases (38.8%) and invasive urothelial cell carcinomas in 30 cases (61.2%). The nuclear DNA content of cancer cells was evaluated using image cytometry allowing the determination of the DNA ploidy and 5cER parameters. The p53 and Ki-67 immunoexpression was evaluated by immunohistochemistry.

Results

CIS lesions were observed in the AM and DM of both tumor groups: 15.8% and 15.4% in AM and DM, for each one of them, in HGP group and 26.7% and 22.2% in AM and DM, for each one of them, in invasive tumors group. In CIS lesion aneuploid DNA content, p53 overexpression and high proliferative labeling index were observed. The so-called normal mucosa (AM and DM) with and without focus of CIS lesions were compared for genetic instability and molecular alterations profile. Statistical differences were observed between the normal mucosa with and without CIS: the so-called normal mucosa areas with focus of CIS revealed significantly higher frequencies of DNA content alterations, p53 overexpression, and higher proliferative index. These differences were significantly different in the invasive UCC group, but this profile it is also present in HPG group.

Conclusion

This study points out that CIS is a marker of genetic instability of the urothelium mucosa. The CIS surrounding morphologically normal urothelium showed a high frequency of abnormal DNA content, with high percentage of clear aneuploid cells (high 5cER), p53 mutated protein expression, and a proliferative status underlying a field carcinogenesis. These alterations in normal mucosa were not found when CIS was not present.

Introduction

Carcinoma in situ (CIS) is a high-grade lesion of the bladder that is confined to the urothelium mucosa, and is included in the superficial urothelial cell carcinoma group (sUCC). It is characterized by flat, disorderly proliferation of cells with marked cytologic abnormalities, and comprises about 10% of all bladder cancers [1].

The clinical experience showed that patients presenting with isolated or concomitant CIS lesions (T1) have a high risk of disease progression to a muscle invasive stage [2]. If transurethral resection (TUR) is the single treatment used, nearly one-half of the patients with CIS progress to invasive disease within 5 years of diagnosis [3].

According to the European Association of Urology (EAU) guidelines for bladder cancer [4], primary CIS confined to the bladder is treated with TUR and intravesical bacillus Calmette-Guerin (BCG) immunotherapy. Despite the complete response rate achieved (83%–93%) [5], [6], as many as 20% of patients will ultimately die of metastatic disease, and a significant proportion will develop both intravesical and extravesical recurrences [1]. Therefore, the high risk of progression to muscle invasive tumors at the time of clinical diagnosis (55%) and the high incidence of bladder cancer recurrence and progression after BCG treatment in this group of patients promote an intense discussion about: (1) Is it reasonable to propose early cystectomy as primary treatment in patients with high grade papillary urothelial carcinoma (HGP) with associated CIS? (2) Should one advocate immediate cystectomy in patients with HGP with associated CIS after BCG failure? (3) Is CIS lesion a surrogate marker of urothelium genetic instability and field carcinogenesis?

In order to answer the last question, we evaluated DNA content, p53 immunoreactivity, and proliferative index (Ki-67 expression) with the objective to identify genetic instability and cell homeostasis deregulation in primary, in tumor-adjacent mucosa, and in distant urothelial mucosa with and without presence of CIS.