It depends on the type of chemotherapeutic agents, of which the oncologist has detailed knowledge. So it's less than half. Oftentimes, the issue is not addressed because of the numerous emotions a patient suddenly faces. They are so overwhelmed by the initial diagnosis. And often it's the wife of a patient who first considers this.
Men can father at most any age, depending on their willingness to parent.
Men in their 30s and 40s who already have families should also consider saving their sperm. No one knows the future. There could be a new marriage, a new spouse and a desire to have children once again. Genetic counseling is done to make sure there are no other major family medical conditions that may be passed on. A blood test is also required by law to screen for HIV and hepatitis.