et al. examine the association between exposure to hormones
during fetal development--both maternal and exogenous--and the risk
of testicular germ-cell cancer. They found that "exogenous
hormone exposure was associated with elevated risk." They also
found that "exposure to maternal hormones, particularly estrogens,
is associated with testicular germ-cell cancer risk.
only does exposure to elevated levels (exogenous hormone use, pre-term
birth, and first birth among young mothers) increase risk, but also
exposure to relatively lower levels (heavy cigarette consumption,
and perhaps, bleeding and threatened miscarriage) may decrease cancer
did they do?
Weir et al. conducted a population-based, case-control
study that focused on all confirmed cases of primary malignant germ-cell
testicular cancer occurring in Ontario residents aged 16-59 between
1 January 1987 and 31 December 1989. Controls in the study were
a population-based random sample of men between aged 16-59.
et al. confirmed the diagnosis of testicular cancer by examining
samples from pathology labs, and then gathered data on risk facters
through use of a self-administered questionnaire sent to the mothers
by the study subjects. Mothers were also interviewed by phone.
621 eligible cases, 502 (80.8%) completed a mailed questionnaire.
Questionnaires were also sent to 1,438 controls, of which 67.8%
participated by returning a completed form.
hormone exposure was determined from the mother's reported use of
prescription hormones (e.g., diethylstilbestrol or premarin), prescription
medication for conditions associated with threatened miscarriage,
injections or pills to determine pregnancy, and use of oral contraceptives
around the time of conception."
did they find?
Weir et al. found that more cases than controls reported
exposure to exogenous hormones. The odds ratio for this risk
factor was 4.9, with the 95% confidence interval running from 1.7
to 13.9. Thus the association was highly significant statistically.
results support the hypothesis that exposure to maternal hormones,
particularly estrogen, is associated with testicular germ-cell cancer
risk. Not only does exposure to elevated levels of maternal hormones
(exogenous hormone use and pre-term birth) appear to increase cancer
risk, but exposure to relatively lower levels of maternal hormones
(heavy cigarette consumption, and, perhaps, bleeding and threatened
miscarriage), , but as measured by indices of exposure to maternal
hormones, appears to decrease cancer risk."
strength of the conclusions reached by Weir et al. are limited
by several factors. Two factors stand out: (1) restrospective questionnaires
that, in this case, attempt to reconstruct details of medical history
that occurred decades in the past are notoriously weak and sometimes
provide inaccurate data. (2) the questionnaire asked about only
a small number of sources of exogenous hormones, all prescription
drugs, that could have been involved. No information was available
about contamination as a source.
does this mean?
These are intriguing results that build upon a previous literature
suggesting (with both positive [e.g., Depue
et al. 1983] and negative [e.g., Brown
et al. 1986] results) that exogenous hormones may play a role
in testicular cancer.