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Testis Cancer
Linda Morris
Brown, M.P.H.*
The testes are the paired male
reproductive glands that produce the hormone testosterone and, after sexual
maturity, spermatozoa (sperm). The testes form in the abdominal cavity early in
fetal development and usually descend into the scrotum before birth. Almost all
testicular cancers are germ cell tumors. There are two major histological
groupings of testicular cancer: seminoma and nonseminoma. Seminomas are more
common in men 35 and older, while nonseminomas are more common in younger men
15-24 (Brown et al., 1986a).
Testicular cancer is rare in the United
States, accounting for only 1 percent of cancers in males. It is, however, the
most common malignancy among white males aged 20 to 34 and the second most
common among white males aged 15 to 19 and 35 to 39. The incidence rate for
white males (5.1 per 100,000) is over six times that for black males (0.8 per
100,000) (Ries et al., 1994). In the United States, the incidence rates of
testicular cancer among Hispanics, Native Americans, and Asians are less than
those for whites, but greater than those for blacks (Muir et al., 1987). Men in
Scandinavian countries have the highest incidence of testicular cancer in the
world--a rate 45 percent greater than that for white men in the United States (Parkin
et al., 1992).
Mortality from testicular cancer is low in
both white (0.3 per 100,000) and black (0.1 per 100,000) U.S. males (Ries et
al., 1994). Because of advances in treatment, survival was 94 percent in
1983-90, up from 79 percent in 1974-76.
The incidence of testicular cancer has
doubled in the past two decades, with the most striking increases occurring
among young men 15-44. Undescended testis, inguinal hernia, testicular trauma,
mumps orchitis, elevated testicular temperature, vasectomy, electromagnetic
fields (EMF), and hormonal, prenatal, and occupational factors have been
implicated in the development of testicular cancer in young adults.
Individuals with cryptorchidism or
undescended testis are at an increased risk for developing testicular cancer,
with approximately 10 percent of testicular cancer patients reporting a history
of this condition. Risks of testicular cancer associated with undescended testes
have ranged from 2.5 to 17.1 (Brown et al., 1987), with the excess risk in
cryptorchid men decreasing with increasingly early age at correction (Pottern et
al., 1985; Strader et al., 1988a).
Inconsistent findings regarding the degree
and significance of the risk of testicular cancer associated with inguinal
(groin) hernia have been reported (Coldman et al., 1982; Pottern et al., 1985;
Swerdlow et al., 1987a). Significantly elevated risks have been suggested for
other antecedent conditions including hydrocele, atrophic testis, and
supernumerary nipples (polythelia) (Goedert et al., 1984; Swerdlow et al.,
1987a; Haughey et al., 1989; Brown et al., 1987). Also, a higher rate of
cryptorchidism, inguinal hernia, and hydrocele was reported in families prone to
testicular cancer, suggesting a relationship between urogenital maldevelopment
and predisposition to testicular cancer (Tollerud et al., 1985).
An association between testicular trauma
and testicular cancer has been suggested (Brown et al., 1987; Coldman et al.,
1982); however, another study (Swerdlow et al., 1988a) found no association with
traumas commonly encountered in everyday life. Although a recent study in
upstate New York (Haughey et al., 1989) reported elevated risks for men who
preferred baths to showers and who reported having a disease associated with a
high fever, three other case-control studies found no excess risk associated
with elevation of testicular temperature by external means (Brown et al., 1987;
Swerdlow et al, 1988a; Karagas et al., 1989). Two suggested risk factors,
vasectomy and EMF exposure from the use of electric blankets, have not been
found to be significant risk factors for testicular cancer (Brown et al., 1987;
Strader et al., 1988a; Verreault et al., 1990).
Maternal factors including nausea of
pregnancy severe enough to require treatment, unusual bleeding or spotting
during pregnancy, as well as low birth weight and early birth order have been
associated with excess risk of testicular cancer (Depue et al., 1983; Brown et
al., 1986b; Swerdlow et al., 1987b; Gershman et al., 1988) and suggest that
raised maternal levels of available estrogen early in pregnancy may be related
to development of testicular cancer in the son. Although in utero DES exposure
has been linked to vaginal cancer in daughters and to testicular abnormalities
in sons of women who took it to prevent miscarriages (DES Task Force, 1981),
prenatal DES exposure has not been linked to testicular cancer (Brown et al.,
1986b; Moss et al., 1986; Gershman et al., 1988).
An association between employment in
professional occupations and the risk of testicular cancer has been reported in
several case-control studies (Graham et al., 1977; Ross et al., 1979; Swerdlow
et al., 1988b). Farming has been associated with excess risk of testicular
cancer in some studies (Mills et al., 1984; Wiklund et al., 1986), but not in
others (Brown and Pottern, 1984; Jensen et al., 1984; Sewell et al., 1986). A
recent case-control study found a significant increase in risk for exposure to
fertilizers (Haughey et al., 1989).
The dramatic increase in testicular cancer
incidence over time for young men suggest that an environmental factor, with a
similar variation over time, might be responsible. Given the magnitude of this
increase, one would expect that this factor should have been identified by
analytical epidemiological studies. However, to date the factors responsible for
these dramatic increases remain elusive. The increases do not appear to be
related to improved diagnostic practices nor to any of the risk factors
identified to date in case-control studies.
REFERENCES
Brown LM, Pottern LM: Testicular cancer
and farming. Lancet 1:1356, 1984.
Brown LM, Pottern LM, Hoover RN, et al.:
Testicular cancer in the United States: Trends in incidence and mortality. Int J
Cancer 15:164-170, 1986a.
Brown LM, Pottern LM and Hoover RN:
Prenatal and perinatal risk factors for testicular cancer. Cancer Res
46:4812-4816, 1986b.
Brown LM, Pottern LM and Hoover RN:
Testicular cancer in young men: The search for causes of the epidemic increase
in the United States. J Epidemiol Commun Health 41:349-354, 1987.
Coldman AJ, Elwood JM and Gallagher RP:
Sports activities and risk of testicular cancer. Br J Cancer 46:749-756, 1982.
Depue RH, Pike MC and Henderson BE:
Estrogen exposure during gestation and risk for testicular cancer. J Natl Cancer
Inst 71:1151-1155, 1983.
DES Task Force Summary Report: DHHS Publ.
No. (NIH) 81-1688. Bethesda, MD, 1981.
Goedert JJ, McKeen EA, Javadpour N, et
al.: Polythelia and testicular cancer. Ann Intern Med 101:646-647, 1984.
Gershman ST and Stolley PD: A case-control
study of testicular cancer using Connecticut Tumor Registry data. Int J
Epidemiol 17:738-742, 1988.
Graham S, Gibson R, West D, et al.:
Epidemiology of cancer of the testis in upstate New York. J Natl Cancer Inst
58:1255-1261, 1977.
Haughey BP, Graham S, Brasure J, et al.:
The epidemiology of testicular cancer in upstate New York. Am J Epidemiol
130:25-36, 1989.
Jensen OM, Olsen JH and Osterlind A:
Testis cancer among farmers in Denmark. Lancet 1:794, 1984.
Karagas MR, Weiss NS, Strader CH, et al.:
Elevated intrascrotal temperature and the incidence of testicular cancer in
noncryptorchid men. Am J Epidemiol 129:1104-1109, 1989.
Mills PK, Newell GR and Johnson DE:
Testicular cancer associated with employment in agriculture and oil and natural
gas extraction. Lancet 1:207-210, 1984.
Moss AR, Osmond D, Bacchetti P, et al:
Hormonal risk factors in testicular cancer--a case-control study. Am J Epidemiol
124:39-52, 1986.
Parkin DM, Muir CS, Whelan S, et al.:
Cancer Incidence in Five Continents, vol VI. IARC Scientific Publication No.
120. World Health Organization, International Agency for Research on Cancer,
Lyon, 1992.
Pottern LM, Brown LM, Hoover RN, et al.:
Testicular cancer risk among young men: Role of cyrptorchidism and inguinal
hernia. J Natl Cancer Inst 74:377-381, 1985.
Ries LAG, Miller BA, Hankey BF, et al.:
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Ross RK, McCurtis RW, Henderson BE, et
al.: Descriptive epidemiology of testicular and prostatic cancer in Los Angeles.
Br J Cancer 39:284-292, 1979.
Sewell CM, Castle SP, Hull HF, et al.:
Testicular cancer and employment in agriculture and oil and natural gas
extraction. Lancet 1:553, 1986.
Strader CH, Weiss NS, Daling JR, et al.:
Cryptorchism, orchiopexy, and the risk of testicular cancer. Am J Epidemiol
127:1013-1018, 1988a.
Strader CH, Weiss NS and Daling JR:
Vasectomy and the incidence of testicular cancer. Am J Epidemiol 128:56-63,
1988b.
Swerdlow AJ, Huttly SRA and Smith PG:
Testicular cancer and antecedent diseases. Br J Cancer 55:97-103, 1987a.
Swerdlow AJ, Huttly SRA and Smith PG:
Prenatal and familial associations of testicular cancer. Br J Cancer 55:571-577,
1987b.
Swerdlow AJ, Huttly SR and Smith PG: Is
the incidence of testis cancer related to trauma or temperature? Br J Urol
61:518-521, 1988a.
Swerdlow AJ and Skeet RG: Occupational
associations of testicular cancer in southeast England. Br J Ind Med 45:225-230,
1988b.
Tollerud DJ, Blattner WA, Fraser MC, et
al.: Familial testicular cancer and urogenital developmental anomalies. Cancer
55:1849-1854, 1985.
Verreault R, Weiss NS, Hollenbach KA, et
al.: Use of electric blankets and risk of testicular cancer. Am J Epidemiol
131:759-762, 1990.
Wiklund K, Dich J and Holm LE: Testicular
cancer among agricultural workers and licensed pesticide applicators in Sweden.
Scand J Work Environ Health 12:630-631, 1986.
*
From the Biostatistics Branch, Division of Cancer Etiology, National Cancer
Institute, Bethesda, Maryland
National Cancer Institute
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