More than 75 percent of male cancer patients become long-term survivors due to medical advances in detection and treatment of cancers. Because cancer survivorship is increasing, quality of life issues, such as being able to conceive children after cancer, are increasingly important. Unfortunately, the same chemotherapies that are saving lives are causing temporary or permanent infertility in cancer survivors.
Sperm Count
After chemotherapy, sperm count commonly decreases compared to pre-treatment levels. Spermatogonia, the stem cells responsible for producing sperm are sensitive to the effects of chemotherapy. Because chemotherapy treatment targets rapidly dividing cells, normal stem cells as well as cancerous cells are susceptible to damage. Damage to spermatogonia can be severe enough to stop all sperm production, leaving no sperm in the ejaculate, a condition called azoospermia. The degree to which the sperm count is affected by chemotherapy depends on the type, dose and duration of chemotherapy used. The addition of radiation therapy can further decrease sperm count. Men with borderline or low counts before treatment are more likely to have extremely low or no sperm in their ejaculate after chemotherapy. Some men will recover their ability to produce sperm and will return to pre-treatment sperm counts, but this may take months or years to achieve. Men are advised to store semen with a sperm bank before their chemotherapy, so that they can use these samples with assisted reproductive techniques to conceive children if their sperm production does not recover after chemotherapy.
DNA Effects
Chemotherapy has been shown to affect the integrity of the DNA in sperm, leading to fertilization problems and infertility. Even when sperm count returns to normal, problems with DNA quality may persist for a longer period. Dr. Sara Frias and her colleagues' scientific findings in the Jan. 1, 2003, journal Cancer Research suggest that chemotherapy causes a temporary increase in sperm aneuploidies. Sperm aneuploidy is a genetic problem in which an abnormal number of chromosomes occurs, particularly for chromosomes X,Y, 18 and 21, increasing the chance that a child will be affected with a chromosomal abnormality like Trisomy 21, which causes Down syndrome. Because of the increased risk of genetic abnormalities, men are advised to avoid conception for at least two years after the last chemotherapy treatment to allow sperm DNA to return to normal, decreasing the possibility that children are born with chromosomal abnormalities.
Hormonal Effects
Specialized cells in the testis called Leydig cells are responsible for producing male hormones, such as testosterone. Leydig cells are fairly resistant to the damaging effects of chemotherapy if standard doses of chemotherapy are used. However, high cumulative doses may cause long-term damage to Leydig cells, according to a study published by Dr. A. Gerl and colleagues in the journal Cancer. Low testosterone levels can cause infertility problems. In some cases, testosterone replacement therapy may be necessary to restore male sexual function and fertility.
