Is it safe to bank sperm if cancer treatment has already been started?

Sometimes we’ll see a patient who’s been diagnosed with cancer, and cancer therapy has been initiated—be it radiation therapy or chemotherapy—and we know these therapies can have an effect, not only on the cancer within the patient’s body, but in many instances also negatively affects sperm develop within the testicle or maturing in the epididimus. The literature is not really clear on when it’s safe to preserve sperm. For instance, say a patient got only one round of chemotherapy, or one treatment—is it safe in that setting to obtain sperm and freeze it for future use? We really don’t know for sure about the safety of that sperm. Our stance at Northwestern has been, and the stance for most people who are interested in fertility preservation around the country, would be to collect sperm in that setting and freeze it—with the realization being that it may not be your first choice for use down the road in the setting of in vitro fertilization, but at the very least there will be some sperm frozen that could potentially be used.