Preserving Fertility in Cancer Patients

Evidence-based fertility preservation strategies for women and men facing gonadotoxic cancer therapy, including ASCO guideline–recommended options and oncofertility referral principles

Key Points

• All reproductive-age patients (generally ≤45 years) facing potentially gonadotoxic treatment should be offered fertility preservation counseling before treatment begins — this is an ASCO guideline requirement regardless of current desire for children.
• The most gonadotoxic agents are alkylating agents (cyclophosphamide, ifosfamide, busulfan, melphalan, procarbazine, chlorambucil) and pelvic/gonadal radiation — these should trigger immediate oncofertility referral.
• Embryo and mature oocyte cryopreservation are established (no longer considered experimental) standard-of-care options for women; the 2-week ovarian stimulation required may delay chemotherapy start — early referral is essential to allow time.
• Sperm banking is fast (1–2 clinic visits), inexpensive, and highly effective — it should be offered to all pubertal males before any gonadotoxic therapy; even one ejaculated sample before treatment greatly improves future reproductive options.
• GnRH agonist cotreatment during chemotherapy may reduce the risk of premature ovarian insufficiency (POI) in premenopausal women with hormone receptor-negative breast cancer but does not replace established cryopreservation strategies.
• Ovarian transposition (oophoropexy) — surgically moving the ovaries out of the radiation field — is a highly effective fertility-preserving option for patients requiring pelvic radiation.

Gonadotoxicity of Cancer Treatments

Understanding which treatments are gonadotoxic is the essential first step — it determines who needs referral and how urgently. **Alkylating agents — the most gonadotoxic class:** Alkylating agents damage primordial follicles (the resting pool of oocytes that determines ovarian reserve) through a mechanism of DNA cross-linking that is not cell-cycle dependent. Because primordial follicles do not proliferate, they cannot repair this damage. - **High gonadotoxicity**: cyclophosphamide, ifosfamide, busulfan, melphalan, chlorambucil, procarbazine, carmustine (BCNU), lomustine (CCNU) - Risk is…

Fertility Preservation Options for Women

**Established (standard of care) options:** *Embryo cryopreservation:* - The most established option with the highest per-transfer success rates (40–50% live birth rate per thawed embryo transfer in women <35) - Requires a male partner or sperm donor; IVF (in vitro fertilization) with ICSI (intracytoplasmic sperm injection) - Process: 10–14 days of controlled ovarian hyperstimulation (COS) with gonadotropin injections → transvaginal oocyte retrieval under sedation → fertilization → embryo culture to blastocyst → cryopreservation - Timing: requires a 2-week delay from treatment start; must be…

Fertility Preservation Options for Men

Fertility preservation in men is generally simpler, faster, and less expensive than in women — there is no reason to delay initiating this conversation. **Sperm banking (semen cryopreservation):** - The standard of care for all pubertal males before any gonadotoxic therapy - Process: masturbation-produced semen sample; collection at a fertility center or via mail-in kit (with appropriate transport conditions) - Requires 2–5 days of abstinence before collection to optimize sperm count - Multiple samples (2–3 separate collections over several days) are preferred to maximize the number of vials…

Timing, the Oncofertility Referral, and Urgent Cases

**Who to refer:** ASCO guidelines recommend fertility preservation counseling for all reproductive-age patients (regardless of current desire for parenthood) facing potentially gonadotoxic therapy. "Reproductive age" is generally defined as patients ≤45 years for women and before puberty or any age for men. **When to refer:** Before cancer treatment begins. The oncofertility conversation and referral must occur at the time of cancer diagnosis, not after treatment has started. Delays — even of days — can eliminate options. **How urgent is urgent:** - Sperm banking: can be completed in 1–2…

Post-Treatment Reproduction and Long-Term Considerations

**When is it safe to attempt pregnancy after cancer treatment?** No universal answer exists — recommendations are tumor-type and treatment-specific: - **Breast cancer**: historically, many oncologists recommended waiting 2 years before attempting pregnancy to identify early relapse and complete adjuvant therapy. Emerging data (POSITIVE trial, NEJM 2023) showed that a temporary interruption of endocrine therapy to attempt pregnancy in ER+ breast cancer patients did not increase short-term recurrence risk at 1.8 years median follow-up — longer-term data pending. ASCO 2024 provisional guidance:…