RISK FACTOR INFORMATION FOR SELECTED CANCER TYPES

Testicular Cancer

Testicle or testicular cancer develops in one or  both  testicles  in men or boys. The annual age- adjusted incidence rate for this cancer is 4.5 cases per 100,000 men or approximately 6,500 cases in the United States per year (Schottenfeld  1996).    Among  Massachusetts’  males,  testicular cancer occurred at a rate of 4.3 cases per 100,000 in 1997.  Testicular cancer is one of the most frequently diagnosed cancers in men between the ages of 20 and 44 (Schottenfeld 1996).  Among this age group, the U.S. age-adjusted incidence of testicular cancer has increased at least fifty percent between 1973 and 1990 (Schottenfeld 1996).   This  increase  is particularly evident in white males, but due to dramatic advances in the diagnosis and treatment of testicular  cancer, age-adjusted mortality rates have declined in this population from 0.8 per 100,000 men in 1973 to
0.3 in 1990 (Schottenfeld 1996).

Over  90% of  cancers of the testicle develop in certain cells known as germ cells (ACS 2000). There are two main types of germ cell tumors (GCTs) in men: seminomas and nonseminomas. About  half  of  all  testicle  germ cell cancers are seminomas.  They develop from the sperm- producing germ cells of the testicle.  There are two main subtypes of these tumors distinguished by their appearance under the microscope: typical (or classic) and spermatocytic.  The average age of men who are diagnosed with spermatocytic seminoma is 65, about 15 years older than the average age of men with typical seminomas (ACS 2000).  Nonseminomas tend to develop earlier in life than seminomas, usually occurring in men in their 20’s (ACS 2000).  The main types of nonseminoma germ cell cancers are embryonal carcinoma, yolk sac carcinoma, choriocarcinoma and teratoma.

Tumors  can  also  arise  in  the  supportive  and  hormone-producing  tissues,  or  stroma,  of  the testicles.  These are known as gonadal  stromal  tumors.  They account for 4% of adult testicle tumors and 20% of childhood testicular tumors (ACS 2000).

Scientists  have found certain risk factors that  make a person more likely to develop testicular cancer.    The  main  risk  factor  for  testicular  cancer  is  a  condition   called   cryptorchidism
(undescended testicle(s)).  About 14% of testicular cancer cases occur in men with a history of cryptorchidism (ACS 2000).  Normally, the testes develop inside the abdomen of the fetus and descend into the scrotum before birth.   In about 3% of males, however, the testes either do not make this decent or descend incompletely.  In the past twenty years, studies have shown that men with  a  history  of  cryptorchidism are 2.5 to 11.4 times more likely to develop testicular cancer than men with no history of cryptorchidism (Schottenfeld 1996).  Some researchers suggest that surgically  correcting  cryptorchidism  before  the   onset   of  puberty  may  reduce  the  risk  of developing testicular cancer later on in life (ACS 2000).

Most testicular cancers occur between the ages of 15 and 40, but this cancer can affect males at any age (ACS 2000).  A family history of testicular cancer increases the risk  of  developing testicular cancer.   If one man has the disease, there is an increased risk that one or more of his brothers will also develop it.  The risk of testicular cancer among white men is about five times that of African-American men and more than double that of Asian-American men.   The reason for this difference is not known (ACS 2000).

Research   has   suggested   that   prenatal   exposure   to   synthetic   estrogens,   like   the   drug diethylstilbestrol (DES), which was used between 1945 and 1960 by pregnant women to prevent miscarriage, can lead to the development of testicular anomalies in male offspring (Schottenfeld
1996).  However, there is no convincing evidence that DES exposure directly increases a man’s risk for developing testicular cancer.

  Source:  Community Assessment Unit, Bureau of Environmental Health Assessment, Massachusetts Department of Public Health
  August 2000

RISK FACTOR INFORMATION FOR SELECTED CANCER TYPES

A recent study suggests that men with  an  occupational history of mining, food and beverage processing, employment in the utilities industry, and employment in the leather industry have an increased  risk  of  developing  testicular  cancer  (Knight et al. 1996).  No particular chemicals, however, have been identified as contributing to  the  development of the disease.  Researchers have also suggested that prolonged occupational exposure to extremely low and extremely high temperatures may increase the risk of developing testicular cancer (Zhang et al. 1995).

Recent research indicates that an association between exposure to polyvinyl chloride  (PVC), during its production phase, and testicular cancer development may exist.  Swedish researchers tentatively  concluded  that  workers  exposed  to  PVC,  while  it  was  being  produced,  had  a significantly elevated risk of testicular cancer development (Hardell et al. 1997).  One hypothesis on  why PVC potentially elevates testicular cancer risk is that production of this plastic often involves the use of phthalates as additives.  Phthalates have been reported to have estrogen-like effects  (Jobling  et  al.  1995).    Therefore,  exposure  to  phthalates  could  increase  the  risk  of development of testicular abnormalities.  Other studies on exposure to PVC, however, found no such elevated risk of  testicular cancer (Hansen 1999, Langard et al. 2000).

References

American Cancer Society. 2000. Testicular Cancer: Prevention and Risk Factors from:
http://www3.cancer.org/cancerinfo/load_cont.asp?st=pr&ct=41&language=english

Hansen J. 1999. Risk for testicular cancer after occupational exposure to plastics.   Int J Cancer
82: 911-912.

Hardell L, Ohlson CG, and Fredrikson M. 1997. Occupational exposure to polyvinyl chloride as a risk factor for testicular cancer evaluated in a case-control study. Int J Cancer 73: 828-830.

Jobling S, Reynolds T, White R, et al. 1995. A variety of environmentally persistent chemicals, including some phthalate plasticizers, are weakly estrogenic. Environ Health Perspect 103: 582-
587.

Knight JA, Marrett LD, and Weir HK. 1996. Occupation and risk of germ cell testicular cancer by histologic type in Ontario. J Occup Environ Med 38: 884-890.

Langard S, Rosenberg J, Andersen A, and Heldaas SS. 2000. Incidence of cancer among workers exposed to vinyl chloride and polyvinyl chloride manufacture. J Occup Environ Med 57: 65-68.

Schottenfeld D. 1996 Testicular Cancer, chapter  56 in Cancer Epidemiology and  Prevention. second ed. Schottenfeld D and Fraumeni JF Jr., eds. Oxford University Press. pp: 1207-1219.

Zhang ZF, Vena JE, Zielezny M, et al. 1995. Occupational exposure to extreme temperature and risk of testicular cancer. Arch Environ Health 50: 13-18.

Source: Community Assessment Unit, Bureau of Environmental Health Assessment, Massachusetts Department of Public Health
August 2000