Semen Cryopreservation in Oncofertility

Impact of cancer on spermatogenesis and sperm uality

Men with cancer often experience impaired gonadal function and present poor sperm uality.^[4] The pathophysiology of cancer can be attributed to metabolic changes, endocrine alterations and systemic conseuences of the disease.^[5] In germ-cell cancers, it has been reported that the direct effect of the tumour, hormonal secretions and immune-mediated factors can interfere with spermatogenesis and sperm functions. Tumours can impinge or infiltrate neurologic structures, leading to ejaculatory disorders, or even affect other parts of the male reproductive system, such as the epididymis, vas deferens and ejaculatory duct, thereby impairing fertility potential.^[6] In haematological cancers, altered general functions, hyperthermia or testicular infiltration could be additional mechanisms responsible for reduced sperm production.^[7] Among various cancers, Hodgkin’s lymphoma (HL) and testicular cancer (TC) are the most prevalent cancers affecting men of reproductive age, with an incidence of 6% and 13–15%, respectively.^[8] Studies have shown that patients with TC, HL and other genitourinary malignancies more often present altered semen profile, particularly reduced semen volume, sperm concentration, and motility when compared to men with other cancers.^[9,10] These variations could be due to the systemic and direct effects of the malignancy, such as inflammation, cytokine production or fever. This could suggest that the mechanisms underlying the decline in sperm uality may be associated with the type and origin of the malignancy.^[11]

Conseuences of cancer treatment on male fertility

With a focus on cancer cure, over time, cancer treatments have evolved, but the common modalities remain chemotherapy and radiotherapy, which are effective in combating malignancies despite their associated gonadotoxicity resulting in male infertility.^[12,13]

Chemotherapy

Chemotherapeutic agents have been shown to cause germinal epithelial damage, resulting in oligo- or azoospermia, as well as Sertoli and Leydig cell damage affecting the hormonal pathways.^[14] The impact of chemotherapy on gonadal function is determined by variables such as the type of drugs, combination regimens and the dose administered.^[15] Each class of cytotoxic drugs has diverse effects on the germ cell stages and depletion rate depending on their modes of action. As a result, the duration and permanence of induced azoospermia are determined by the dosage of the drug, the freuency and the cumulative impact of the other agents administered. Alkylating drugs such as cyclophosphamide, chlorambucil, procarbazine and busulphan can pose a high risk to fertility. For instance, a single dose of 300 mg/kg cyclophosphamide causes azoospermia in over 80% of males within 50–60 days of treatment, which can lead to irreversible infertility.^[16] Cisplatin, at a threshold level of 600 mg/m², results in temporary azoospermia with a recovery of spermatogenesis in about 50% of patients in 2 years, whereas vinblastine, at 50 g/m², has an intermediate risk of infertility, resulting in temporary oligozoospermia, but is usually administered in conjunction with other sterilising agents.^[15,17]

Radiation therapy

The testis is a highly radiosensitive organ as it contains the proliferating spermatogonial stem cells (SSC). The testicular function can be impaired by direct testicular, pelvic, hypothalamic–pituitary axis irradiation or scattered radiation.^[18] As radiation directly targets the DNA of proliferating cells, the SSC gets affected as a conseuence, but the differentiated spermatocytes, spermatids and spermatozoa are less vulnerable to radiation toxicity. Direct testicular irradiation can result in azoospermia (>2.0 Gy), permanent oligozoospermia (0.8–2.0 Gy) or transient oligozoospermia (<0.8 Gy). A dose of 8 Gy can induce azoospermia in nearly all men, incurring permanent damage to spermatogenesis.^[19] The severity and duration of gonadal damage are influenced by a number of variables, such as dose, fraction size and the specific target cell population.^[20]

Time for spermatogenic recovery after therapeutic insult

Testicular dysfunction and germinal epithelial damage can result from cytotoxic treatment, SSC uality and their differentiation ability. Gonadotoxic effects and recovery time depend on initial semen uality, delivery method, treatment regimens, as well as the spermatogenesis phase.^[21] For instance, recolonisation of surviving SSC can be detected by 6 months after exposure to a dose of 0.2 Gy, or up to 9–18 months following a dose of 1 Gy, and sometimes greater than 4 years after exposure to 10 Gy. Combination regimens of CP with busulphan or thiotepa have shown sperm recovery after 3 years, and in 50 % of cases, sperm were observed in the ejaculate after 7 years.^[22] Combination treatment with radiotherapy and chemotherapy can induce further gonadotoxic damage to the testis.

Genetic normalcy of sperm after cancer therapy

Cancer survivors are more likely to have sperm with aneuploidy, DNA damage, aberrant chromatin structure and epigenetic modifications, even after 2 years of initial treatment in addition to alterations to conventional semen parameters.^[23] Sperm DNA aberration is a serious clinical concern because male cancer survivors might use gametes with potentially damaged genomes for assisted reproduction technology (ART) cycles, which could result in adverse reproductive outcomes.^[24] A study has shown a reduced pregnancy rate (20%) in ART cycles, which used sperm exposed to cancer treatments compared to the use of sperm that was cryopreserved before cancer therapy, which reported a higher pregnancy rate (51.4%).^[25] The altered sperm epigenome of treated males could lead to a transgenerational transmission mechanism affecting the progeny.^[26] Sperm chromatin damage resulting in genome instability is one of the most important reproductive side effects owing to the malignancy and/or its treatment^[27] which cannot be reversed. Therefore, it’s crucial for these individuals to opt for FP before cancer treatment, as the chances of genetic damage to the sperm increase significantly even 1 day post-treatment with alkylating agents.^[28]

Semen cryopreservation: The gold standard

SC is a well-established, non-invasive FP strategy for adolescents and adult males.^[29] SC, in conjugation with ART, has revolutionised the FP and restoration options in oncofertility thereby improving the uality of life of cancer survivors.^[30] The birth of twins through IVF (in vitro fertilisation) using semen that had been frozen for about 40 years has been chronicled, reassuring that even with long-term cryopreservation, sperm retain the fertilisation ability, resulting in healthy offspring.^[31] Some patients may be unable to ejaculate on demand due to various factors such as prevailing illness, age, local pain, psychological issues, cultural factors, or religious concerns. For such patients, penile vibratory stimulation or electroejaculation (EJ) can be performed to obtain the semen sample. Even for patients with time constraints, EJ is more suitable. SC is not just limited to adults; peripubertal boys at around the age of 12 years usually reach spermarche, at which point they acuire secondary sexual characteristics. Depending on their physical capacity and emotional maturity to provide a sample by masturbation, SC can be offered.^[32]

SC pre- and post-therapy: Laboratory aspects

Semen banking can be offered to all AYA male cancer patients at the time of diagnosis after thorough counselling for FP. SC involves semen collection, analysis, preparation, and freezing with the addition of cryoprotectants and storage in liuid nitrogen. Among the various cryopreservation techniues, rapid freezing (RF) is the uickest and most effective techniue that has shown superior post-thaw motility and cryo-survival than slow freezing.^[33] RF involves drop-wise mixing of sample and cryoprotectant in a 1:1 ratio; followed by incubation at 4°C for 10 minutes. After that, the straws are placed in the vapour phase of liuid nitrogen (−80°C) for 15 minutes before being immersed in liuid nitrogen.^[34] The protocols for sperm banking have been established globally and any modifications to the freezing protocol would be dependent on the type of commercially available sperm freezing medium.^[35]

Typically, 3–5 days of ejaculatory abstinence is followed for routine therapeutic sperm banking. However, such compliance may delay the initiation of the treatment in cancer patients. A study on sperm collected for FP revealed that the post-thaw uality of sperm produced after 24-48 hours of abstinence was comparable to that of longer abstinence.^[36] This consideration will allow for a more freuent collection schedule, enabling patients to store multiple samples. The number of samples to be stored is determined by the semen uality, time-to-treatment, health status of the patient and fertility restoration strategy. For patients with mild or severe oligoasthenozoospermia, it is crucial to store multiple samples or aliuots. Nevertheless, in such cases of limitedly available samples, ICSI (intracytoplasmic sperm injection) could potentially enable them to father a child. As it is evident that cancer therapies result in sperm DNA damage and sperm concentration depletion, SC should ideally be performed prior to initiation of the therapy. However, when a patient desires to store sperm after cancer treatment, experts recommend a 1-year waiting period after the completion of the last cycle of chemo- or radiotherapy.^[37]

Guidelines for male FP

Due to the negative impact of cancer and/or its treatment on fertility, international organisations such as the American Society of Clinical Oncology (ASCO), ASRM and ESHRE recommend that healthcare professionals should discuss sperm banking with adolescents and young adult males before their cancer treatment.^[38–41] Although sperm uality may be reduced even before starting therapy, and there may be a need to start chemotherapy immediately, leaving patients with limited time to provide optimal number of ejaculates for FP; these concerns should not dissuade patients from sperm banking.^[42] Individualised oncofertility counselling should be provided with a focus on the patient’s interest and understanding capacity, their age, as well as the planned treatment regimen. Wherever possible, patients should be provided with written information or access to online resources during oncofertility counselling.^[43]

The indications for oncofertility include childhood malignancy, treatment with high-risk chemotherapy drugs or total body irradiation, or conditioning before haematopoietic stem cell transplantation.^[44] However, as there is no absolute threshold of anticancer therapy exposure that determines gonadal failure and infertility, every patient should be regarded as potentially at risk of developing treatment-related gonadotoxicity.^[43]

Barriers to FP and ethical considerations

Despite the professional international guidelines and recommendations for FP in cancer patients, timely referrals and the number and patients opting for FP remain low owing to several barriers.^[45] The barriers to FP referrals include limited knowledge and training among health care providers, prioritising cancer treatment, additional costs for the patients, emotional impact, limited time to treatment and a lack of familial support. Another aspect is the complexity of FP discussions in the face of life-threatening situations such as a cancer diagnosis.^[46] However, it is very important to obtain informed consent from patients or parents of adolescent boys before the procedure.^[47]

The barriers at the level of the institution include a lack of trained professionals, insufficient resources or a lack of infrastructure.^[45,48] The disposition of cryopreserved samples is another critical consideration, especially for pre- or peripubertal boys who might reuire long-term storage. Other barriers such as underutilisation of stored samples, decision-making for disposal and a lack of follow-up can also pose a significant ethical burden on the FP units.^[49] By bridging care gaps and addressing access barriers, providing oncofertility education, resources, support and timely access to fertility-related care, FP can be easily implemented as part of standard cancer care.^[50]