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

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

Harrison's Internal Medicine > Chapter 90. Bladder and Renal Cell
Carcinomas
Bladder Cancer
A 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 of incidence to mortality reflects the higher frequency
of the less lethal superficial variants compared to the more lethal invasive and
metastatic variants. The incidence is three times higher in men than in women, and
twofold higher in whites than blacks, with a median age at diagnosis of 65 years.
Once diagnosed, urothelial tumors exhibit polychronotropism—the
tendency to recur over time and in new locations in the urothelial tract. As long as
urothelium is present, continuous monitoring of the tract is required.
Epidemiology
Cigarette smoking is believed to contribute to up to 50% of the diagnosed
urothelial cancers in men and up to 40% in women. The risk of developing a
urothelial malignancy in male smokers is increased two- to fourfold relative to
nonsmokers and continues for 10 years or longer after cessation. Other implicated
agents include the aniline dyes, the drugs phenacetin and chlornaphazine, and
external beam radiation. Chronic cyclophosphamide exposure may also increase
risk, whereas vitamin A supplements appear to be protective. Exposure to
Schistosoma haematobium, a parasite found in many developing countries, is
associated with an increase in both squamous and transitional cell carcinomas of
the bladder.

Pathology
Clinical subtypes are grouped into three categories: 75% are superficial,
20% invade muscle, and 5% are metastatic at presentation. Staging of the tumor
within the bladder is based on the pattern of growth and depth of invasion: Ta
lesions grow as exophytic lesions; carcinoma in situ (CIS) lesions start on the
surface and tend to invade. The revised tumor, node, metastasis (TNM) staging
system is illustrated in Fig. 90-1. About half of invasive tumors presented
originally as superficial lesions that later progressed. Tumors are also rated by
grade. Grade I lesions (highly differentiated tumors) rarely progress to a higher
stage, 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 cell
in origin. Pure squamous cancers with keratinization constitute 3%,
adenocarcinomas 2%, and small cell tumors (with paraneoplastic syndromes)
<1%. Adenocarcinomas develop primarily in the urachal remnant in the dome of
the bladder or in the periurethral tissues; some assume a signet cell histology.
Lymphomas and melanomas are rare. Of the transitional cell tumors, low-grade
papillary lesions that grow on a central stalk are most common. These tumors are
very friable, have a tendency to bleed, are at high risk for recurrence, and yet
rarely progress to the more lethal invasive variety. In contrast, CIS is a high-grade
tumor that is considered a precursor of the more lethal muscle-invasive disease.