Children,
Cancer, and the EnvironmentChildren,
Cancer, and the EnvironmentGerm cell tumors most commonly occur in the reproductive organs including the ovary and testes. However, these tumors can also occur elsewhere in the body, including in the spine or skull. Germ cell tumors are cancers of primitive cells that come from a very early stage in the development of a fetus. The tumors are thought to develop from cells that migrate incorrectly to the wrong place in the body while the fetus was developing.
Germ cell tumors are a rare kind of cancer in children, but they are a form that is increasing in frequency (1, 2). The frequency of testicular cancer in particular has increased rapidly in adults males and boys over the last twenty years, though the causes are unknown (3). The increase in testicular cancer germ cell tumors appears to be international (1). There is some evidence that the average age at which males are affected may be getting younger (4).
Germ cell tumors occur most commonly during the adolescent years from age 15 to 20, representing about 14% of cancers for this age group. Such tumors are more common in white children than black children.
The patterns for ages at which the cancers occur are different for boys and girls. For males, germ cell tumors are relatively more common during the first year of life. Then, the frequency decreases until males reach adolescence (2). Some scientists suggest that germ cell tumors in very young children may be caused by genetic events or environmental exposures that occur before birth while those in older children may result from such occurrences during childhood (5).
For younger children, germ cell tumors are more common in areas other than the reproductive organs (6).
For females, the pattern is quite different. The frequency of germ cell tumors is very low in early childhood. The frequency of ovarian germ cell tumors begins to increase around age 8 and continues to increase until reaching a maximum at age 18 (2). Testicular cancer in adolescent boys is about three times more common than ovarian cancer in adolescent girls.
The causes of germ cell tumors are not known. Boys with testicular cancer are also more likely to have experienced cryptorchidism (undescended testicles) (7, 8). Some scientists think that the two conditions may have common causes and that they may be related to exposure to hormones in the womb, though whether such hormones might be naturally-occurring or from external sources is unknown (9, 10).
There is some limited evidence that certain types of viruses may increase the risk of germ cell tumors (10).
Exposure to X-rays during the prenatal period and maternal exposure to certain chemical or physical agents including solvents or paternal exposure to X rays also may contribute to the formation of the tumors (11, 12).
One study conducted by the Childhood Cancer Research Group compared children with germ cell tumors to other children from the same communities (13). This study found that the parents of children with malignant germ cell tumors were more likely than the parents of healthy children to report that they had been exposed to chemicals, solvents, or plastic and resin. In particular, mothers were four and a half times more likely to report exposure to solvents and twelve times more likely to report exposures to plastic or resin fumes. Fathers were twice as likely to report exposures to solvents or plastic or resin fumes.
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References
1. dos Santos Silva I, Swerdlow AJ, Stiller CA, Reid A. Incidence of testicular germ-cell malignancies in England and Wales: trends in children compared with adults. International Journal of Cancer 1999; 83:630-4.
2. Bernstein L, Smith MA, Liu L, Deapen D, Friedman DL. Germ Cell, Trophophastic, and Other Gonadal Neoplasms (ICCC X). In: Ries LAG, Smith MA, Gurney JG, Linet M, Tamra T, Young JL, Bunin GR, eds. Cancer Incidence and Survival Among Children and Adolescents: United States SEER Program 1975-1995. Bethesda Md: Cancer Statistics Branch, Cancer Surveillance Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, 1999:125-138.
3. Gilliland FD, Key CR. Male genital cancers. Cancer 1995; 75:295-315.
4. McKiernan JM, Goluboff ET, Liberson GL, Golden R, Fisch H. Rising risk of testicular cancer by birth cohort in the United States from 1973 to 1995. Journal of Urology 1999; 162:361-3.
5. Visfeldt J, Jørgensen N, Müller J, Møller H, Skakkebaek NE. Testicular germ cell tumours of childhood in Denmark, 1943-1989: incidence and evaluation of histology using immunohistochemical techniques. Journal of Pathology 1994; 174:39-47.
6. Rescorla FJ, Breitfeld PP. Pediatric germ cell tumors. Current Problems in Cancer 1999; 23:257-303.
7. Swerdlow AJ, Higgins CD, Pike MC. Risk of testicular cancer in cohort of boys with cryptorchidism. British Medical Journal (Clinical Research Ed.) 1997; 314:1507-11.
8. Møller H, Prener A, Skakkebaek NE. Testicular cancer, cryptorchidism, inguinal hernia, testicular atrophy, and genital malformations: case-control studies in Denmark. Cancer Causes and Control 1996; 7:264-74.
9. Sharpe RM, Skakkebaek NE. Are oestrogens involved in falling sperm counts and disorders of the male reproductive tract? Lancet 1993; 341:1392-5.
10. Wanderås EH, Grotmol T, Fosså SD, Tretli S. Maternal health and pre- and perinatal characteristics in the etiology of testicular cancer: a prospective population- and register-based study on Norwegian males born between 1967 and 1995. Cancer Causes and Control 1998; 9:475-86.
11. Kardaun JW, Hayes RB, Pottern LM, Brown LM, Hoover RN. Testicular cancer in young men and parental occupational exposure. American Journal of Industrial Medicine 1991; 20:219-27.
12. Johnston HE, Mann JR, Williams J, Waterhouse JA, Birch JM, Cartwright RA, Draper GJ, Hartley AL, McKinney PA, Hopton PA, et al. The Inter-Regional, Epidemiological Study of Childhood Cancer (IRESCC): case-control study in children with germ cell tumours. Carcinogenesis 1986; 7:717-22.
13. Shu XO, Nesbit ME, Buckley JD, Krailo MD, Robinson LL. An exploratory analysis of risk factors for childhood malignant germ-cell tumors: report from the Childrens Cancer Group (Canada, United States). Cancer Causes and Control 1995; 6:187-98.
