The semineferous tubules of the testis lie dormant until puberty, when spermatogenesis begins under the influence of testosterone and leutenizing hormone. Sperm can be cryopreserved once they are produced, preserving the patient's fertility even if their gonads lose the ability to produce more.
Germ cell tumours of the testis are often associated with low sperm counts, even in the 'normal' contralateral testis. Men should be offered cryopreservation prior to undergoing adjuvant therapies.
Hodgkin's disease is also associated with higher than expected infertility rates through an unknown mechanism.
Surgery that removes the testes, or otherwise impairs the flow of sperm from the testis to the penis, can result in infertility. Surgery that impairs the nerves to the internal genitals can also impair fertility (retroperitoneal lymph nodes, prostate).
The threshold dose for infertility is about 1 Gy with a fractionated regimes.
Fertility should be discussed with all patients having pelvic and lower limb radiotherapy and cryopreservation of sperm suggested.
Methods of avoiding
Alkylating agents are very potent against the spermatocytes and lead to infertility if included in part of a treatment regiment. Combination agents are even more toxic if they contain alkylating agents.
In children, the testes are relatively resistant but azoospermia can still result if high doses are used (eg. MOPP).
Chemotherapy rarely impacts on the function of the internal and external genitalia aside from the effects on the germinal epithelium.
Testosterone and FSH are both required for normal spermatogenesis. Therefore, inhibition of production of these hormones can lead to development of fertility failure.
Normal sexual function of the male genitals requires:
- Functioning hormonal system, consisting of the hypothalamic/pituitary/testes axis
- Functioning innervation of the genitals including autonomic innervation
- Functional prostate, vas deferens, seminal vesicles, urethra and penis
Malignancy and its treatment can impact on these three areas.