In some circumstances, the process of cancer treatment might make it difficult for a person to produce an egg that will lead to a pregnancy. By retrieving and freezing eggs before cancer treatment begins, the patient has preserved a pool of unaffected eggs (or, if fertilized, embryos) that are available if they have challenges conceiving after cancer treatment.

How often those eggs lead to a live birth if needed tends to be a function of three factors: the age at which they were retrieved (younger tends to be better), the number of eggs frozen (more tends to be better), and the skill of the laboratories that handle the eggs.

Below are data from 80 “oncofertility” patients who had their eggs retrieved and ultimately returned back to use them. While this is a smaller study, conducted at a single Spanish fertility center (with a lot of expertise in egg freezing), it illustrates the varying degree to which freezing one’s eggs leads to a live birth.

A fertility doctor, referred to as a Reproductive Endocrinologist, oversees the egg freezing process. Reproductive Endocrinologists are OBGYN sub-specialists and are variably well-versed in the nuances of a cancer diagnosis or cancer care.

The costs to freeze eggs can be high but if a patient is able to move forward, there are typically six major steps in the process: selecting a clinic, diagnostic testing, taking injectable hormones, the trigger shot, the egg retrieval itself and the clinic’s efforts to freeze eggs or (if those eggs are fertilized) embryos. Below is a chart covering the critical steps and a brief description of each. In later chapters, we will cover these steps in more detail.

Process Overview

Step 1: Selecting a Fertility Clinic: Fertility doctors work in a clinic that is often associated with a laboratory that handles eggs and sperm. The steps taken to freeze eggs (or to fertilize them) are nuanced, and there is a wide variety of laboratories. Ideally, one would have the time to ensure the clinic’s laboratory is of high quality. (Other considerations may include the clinic’s experience treating cancer patients, policies on pricing, reimbursement, and their ability to get you in quickly. We’ll discuss clinic selection later on.)

Step 2: Diagnostic Testing: Should a person decide to continue on, the fertility clinic will conduct a number of non-invasive blood tests (e.g. AMH) and/or a pelvic ultrasound to determine how a patient will respond to the drugs and how many eggs they’ll produce.

Step 3: Hormone Injections: For a period of one to two weeks, patients inject themselves with hormones to grow an abnormally high number of follicles (where eggs develop) in their ovaries. On one hand, more injectable drugs (called gonadotropins) tend to help mature more eggs. On the other hand, they raise a patient’s estrogen level and the impact on cancer patients needs to be monitored closely. The combination of drugs (known as a “protocol”) a patient is put on should be adapted given the patient’s cancer diagnosis and treatment timing.

Adapting Hormones for Cancer Patients:

• A “random start” protocol allows patients to start injections quickly at any time in their menstrual cycle (shortening the delay to their retrieval, and in turn, their cancer care)

• Drugs like letrozole or tamoxifen may help moderate estrogen rises (especially important in some cancers, like some forms of breast cancer)

Step 4: Trigger Shot: One final set of injections is taken (the timing must be exact) 35-37 hours before an egg retrieval to ensure eggs mature within the follicle and can be retrieved by the fertility doctor.

Step 5: Egg Retrieval: With the patient under light anesthesia, a doctor retrieves eggs from the patient’s ovarian follicles. The complication rate associated with the retrieval is less than 1%, and the vast majority of patients recover within a few days.

Step 6: Freeze Eggs or Embryos: The clinic’s laboratory will be given the retrieved eggs and either A.) immediately freeze them or B.) fertilize the eggs, develop them into embryos, and then freeze the embryos. Later, we’ll discuss the positives and negatives of freezing eggs or embryos but in short, freezing eggs leaves the door open to fertilize eggs with any person’s sperm. Freezing embryos gives better visibility into whether the eggs can be fertilized, whether they can develop into embryos, and ultimately, whether they could lead to a pregnancy. Either way, the quality of the laboratory is paramount, and even if all previous four steps are done correctly, an error in the freezing process can put the whole process at risk.