Joseph K. McLaughlin, Ph.D.*
|Malignant tumors of the kidney account for 2 percent of
all new cancers each year in the United States. In 1994, there were
approximately 27,600 new cases of kidney cancer and about 11,300
deaths; 60 percent of both new cases and deaths occur in men (Ries
et al., 1994).
Renal cell cancer and renal pelvis cancer account for 70 percent and 15 percent of the tumors, respectively, with the remainder being primarily composed of cancer of the ureter (8 percent) and urethra (4 percent) (Devesa et al., 1990). Renal cell cancers develop in the main area of the kidney (renal parenchyma), while renal pelvis cancers develop in the lower part of the kidney where urine collects and begins its journey to the bladder via the ureter.
Internationally, the incidence rates for kidney cancer are highest in European and Scandinavian countries and North America (Parkin et al., 1992). In the United States, the incidence rate per 100,000 for renal cell cancer is 8.4 among white men, 8.6 among black men, 3.7 among white women, and 5.6 among black women (Devesa et al., 1990). The incidence rates for renal pelvis and ureter cancers are much lower, averaging between 1 and 2 per 100,000 for men and women of both races. Since the early 1970s, incidence rates for renal cell cancer have been increasing an average of 2 percent per year, and 3 percent per year for renal pelvis and ureter cancers (Devesa et al., 1990). The five-year relative survival rate for patients with renal cell cancer is about 50 percent, but for those with renal pelvis and ureter cancers the rate is about 65 percent (McLaughlin et al., in press). Wilms' tumor of the kidney (nephroblastoma) is found only among young children and is discussed in another section of this book (see Childhood Cancers).
Renal cell, renal pelvis, and ureter cancers share a number of risk factors (McLaughlin et al., 1983, 1984, 1992). Cigarette smoking is causally linked to these tumors, although the association with renal pelvis and ureter cancers is much stronger (McLaughlin et al., 1992). Risk ratios ranging from 1.5 to 2.5 have been reported for cigarette smoking and renal cell cancer, while ratios of 2.5- to 7-fold have been reported for renal pelvis and ureter cancers (McLaughlin et al., in press). Approximately 30 percent of renal cell cancers among men and 24 percent among women are attributable to cigarette smoking, while about 70 percent of the renal pelvis and ureter cancers among men and 40 percent among women can be linked to smoking.
Abuse of analgesics (particularly phenacetin-containing pain relievers) has been causally linked to cancers of the renal pelvis and ureter in a number of studies (McLaughlin et al., in press; IARC, 1987). More recently, long-term use of phenacetin-containing analgesics has also been associated with an increased risk of renal cell cancer (McLaughlin et al,. 1985; McCredie et al., 1988). However, similar to cigarette smoking, the association with phenacetin-containing drugs is much stronger among patients with renal pelvis and ureter cancers than among renal cell cancer patients. In the United States, phenacetin-containing analgesics have not been available in over-the-counter preparations since the late 1970s. Recently, an increased risk of renal cell cancer has been reported for regular use of prescription diuretics (Yu et al., 1986; McLaughlin et al., 1988), but further research is needed before any firm conclusions can be drawn.
A consistent risk factor for renal cell cancer, found in virtually all studies, is that of high relative weight or obesity. Although early studies noted the association primarily among women, more recent studies have also found an increased risk among overweight men (McLaughlin et al., in press). The reason for this association is unknown, and obesity is not related to the other tumors of the kidney.
Beverages such as coffee, tea, and alcoholic drinks have not been found to be important risk factors for renal cell, renal pelvis, or ureter cancers (McLaughlin et al., in press). Dietary findings are sparse for these tumors, although some studies have reported renal cell cancer to be associated with increased meat consumption (McLaughlin et al., 1984; Maclure and Willett, 1990).
Occupation contributes little to the etiology of renal cell cancer, although some studies have found death from kidney cancer to be elevated among asbestos-exposed workers (Selikoff et al., 1979), and among coke-oven workers in steel plants (Redmond, 1983). Because of the relative rarity of cancers of the renal pelvis and ureter, there have been few occupational reports on these tumors.
Given our present knowledge, prevention of these cancers is best achieved by cessation of cigarette smoking. About one-third of renal cell cancers and more than one-half of renal pelvis and ureter cancers could be avoided by eliminating the use of tobacco.