Chapter 090. Bladder and Renal Cell Carcinomas (Part 1)

Harrisons Internal Medicine Chapter 90. Bladder and Renal Cell CarcinomasBladder CancerA transitional cell epithelium lines the urinary tract from the renal pelvis to the ureter, urinary bladder, and the proximal two-thirds of the urethra. Cancers can occur at any point: 90% of malignancies develop in the bladder, 8% in the renal pelvis, and the remaining 2% in the ureter or urethra. Bladder cancer is the fourth most common cancer in men and the thirteenth in women, with an estimated 67,160 new cases and 13,750 deaths in the United States predicted for the year 2007. The almost 5:1 ratio...
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Chapter 090. Bladder and Renal Cell Carcinomas (Part 1) Chapter 090. Bladder and Renal Cell Carcinomas (Part 1) Harrisons Internal Medicine > Chapter 90. Bladder and Renal CellCarcinomas Bladder Cancer A transitional cell epithelium lines the urinary tract from the renal pelvis tothe ureter, urinary bladder, and the proximal two-thirds of the urethra. Cancers canoccur at any point: 90% of malignancies develop in the bladder, 8% in the renalpelvis, and the remaining 2% in the ureter or urethra. Bladder cancer is the fourthmost common cancer in men and the thirteenth in women, with an estimated67,160 new cases and 13,750 deaths in the United States predicted for the year2007. The almost 5:1 ratio of incidence to mortality reflects the higher frequencyof the less lethal superficial variants compared to the more lethal invasive andmetastatic variants. The incidence is three times higher in men than in women, andtwofold higher in whites than blacks, with a median age at diagnosis of 65 years. Once diagnosed, urothelial tumors exhibit polychronotropism—thetendency to recur over time and in new locations in the urothelial tract. As long asurothelium is present, continuous monitoring of the tract is required. Epidemiology Cigarette smoking is believed to contribute to up to 50% of the diagnosedurothelial cancers in men and up to 40% in women. The risk of developing aurothelial malignancy in male smokers is increased two- to fourfold relative tononsmokers and continues for 10 years or longer after cessation. Other implicatedagents include the aniline dyes, the drugs phenacetin and chlornaphazine, andexternal beam radiation. Chronic cyclophosphamide exposure may also increaserisk, whereas vitamin A supplements appear to be protective. Exposure toSchistosoma haematobium, a parasite found in many developing countries, isassociated with an increase in both squamous and transitional cell carcinomas ofthe bladder. Pathology Clinical subtypes are grouped into three categories: 75% are superficial,20% invade muscle, and 5% are metastatic at presentation. Staging of the tumorwithin the bladder is based on the pattern of growth and depth of invasion: Talesions grow as exophytic lesions; carcinoma in situ (CIS) lesions start on thesurface and tend to invade. The revised tumor, node, metastasis (TNM) stagingsystem is illustrated in Fig. 90-1. About half of invasive tumors presentedoriginally as superficial lesions that later progressed. Tumors are also rated bygrade. Grade I lesions (highly differentiated tumors) rarely progress to a higherstage, whereas grade III tumors do. Figure 90-1 Bladder staging. TNM, tumor, node, metastasis. More than 95% of urothelial tumors in the United States are transitional cellin origin. Pure squamous cancers with keratinization constitute 3%,adenocarcinomas 2%, and small cell tumors (with paraneoplastic syndromes)Lymphomas and melanomas are rare. Of the transitional cell tumors, low-gradepapillary lesions that grow on a central stalk are most common. These tumors arevery friable, have a tendency to bleed, are at high risk for recurrence, and yetrarely progress to the more lethal invasive variety. In contrast, CIS is a high-gradetumor that is considered a precursor of the more lethal muscle-invasive disease.