Testicular biopsy

In men and boys with cancer does the use of testicular biopsy result in pregnancy and live birth? Is there any evidence of harm from the harvesting procedure?

Chemotherapy, radiation and surgical treatments can result in temporary or permanent infertility for men. The collection of and cryopreservation of spermatozoa in semen is recommend in peri-pubertal and pubertal patients. However, options are unproven in pre-pubertal boys who are not yet making mature sperm. In this group cryopreservation of testicular tissue containing stem cells may be considered to provide hope for future fertility treatment options once these patients reach adulthood.^[1]

Testicular spermatids may be recovered from testicular biopsies and used for intracytoplasmic sperm injection in azoospermic adults who have already undergone cancer treatments and are now desiring fertility treatment. The harvesting procedure itself is known as testicular sperm extraction or TESE. Spermatids may be extracted from fresh biopsies or cryopreserved tissues taken from post-pubertal boys before treatment, but this is still regarded as highly experimental.

Spermatogonial stem cells are present in testicular tissue in pre-pubertal boys even when mature spermatids are not. Collection of testicular tissue from pre-pubertal boys under general anaesthetic is usually combined with other diagnostic or therapeutic procedures. This is a low risk approach^{[2][3][4][5][6]} however, caution should be exercised as there is a potential risk of contamination with disruption of the blood testis barrier for boys with acute leukaemia^.[7]

Testicular biopsy for fertility preservation in pre-pubertal boys remains an unproven procedure as it is not currently possible to use these stem cells in fertility treatment. There is a paucity of published research in this area, with a total of six studies included which address this part of the question and this patient group.^{[2][8][3][4][9][5]} Cryopreservation of testicular tissue in this setting is therefore done with the expectation that future technology will allow in vitro maturation of these stem cells, or that in vivo transplantation would allow natural restoration of spermatogenesis and fertility. A recent publication regarding in vitro maturation in macaques resulting in livebirth provides encouragement for eventual success in humans.^[10]

Evidence summary one

Recommendation One

In mid and late-pubertal boys with a testicular volume of ≥ 8 ml and men who are too unwell or otherwise unable to ejaculate, sperm can be harvested under general anaesthesia by testicular sperm extraction (TESE). There are several approaches to tissue collection including needle aspiration, open biopsy with random sampling of several sites or the more technically demanding microdissection testicular sperm extraction (microTESE) procedure using an operative microscope. Overall, microTESE has the highest yield of sperm from azoospermic patients in general (Bernie 2015, Deruyver 2014), but there are a limited number of surgeons trained and experienced in microTESE in Australia.

Depending on the clinical setting, sperm retrieval rates from cryopreserved testicular tissue are between 42-67%.^{[11][12][13][14][15][16]} The majority of these studies are small case series, but larger studies were of 49 patients^[11] and 66 patients.^[15]

The risk of these procedures is low (reported at zero to ~5%), with adverse outcomes reported as; none,^{[2][11][8][3]} one scrotal haematoma out of 175 patients,^[17] one each of epididymo-orchitis and self-resolving torsion of the appendix testis out of 27 patients,^[4] one scrotal wound dehiscence out of 11 patients (Ho 2017) and wound infection in two out of 78 patients.^[9] Longer term outcomes include intra-scrotal haematomas in 10.9%, all completely resolving by six months, and very small fibrotic lesions remaining in 6.3% of boys by 12 months.^[9] There was no impact seen in testicular growth in boys who underwent micro-TESE,^[9] and no long-term risks for boys who had a testicular biopsy were detected during clinical follow-up (Borgstrom 2020). The effect of microTESE on serum testosterone levels was not assessed in any of the included studies.

Fresh sperm retrieved from testicular tissue of cancer patients has been reported to achieve between 42%^[18] and 59% (Dar 2018) live birth rates, in large centres experienced in microTESE. While sperm extracted from the testicular tissue of cancer patients, and used for ICSI results in fertilisation rates of approximately 30-65%,^{[17][14][19][15][16][20]} there is a paucity of data with regard to pregnancy and live birth rates. Seven studies included data on pregnancy rates,^{[12][13][17][14][15][16][20]} and there was one additional case study with n = 1.^[19] Five studies included live birth rates,^{[17][14][15][16][20]}), one study combined the outcomes of ongoing pregnancy and birth rates^[12] and there was one additional case report with n=1.^[19] In those cases with n > 1, and assuming that the two patients in Damani et al. both had a live birth, there was an overall pregnancy rate of 30%, and live birth rate of 63/315 (20%).^[12]

In a cancer context, sperm are often frozen for use some many years later, which adds a further degree of complexity to conducting research in this area. Despite the relative paucity of data, consistent clinical observations show that sperm extracted from testicular tissue works effectively with ICSI and that there is relatively low risk from surgery. This approach serves as a mean to circumvent later childlessness associated with gonadal damage from cancer treatments.

This is an area with very little evidence base to guide clinical practice. Larger studies are needed, and the main focus of research needs to shift to clinically relevant outcomes, particularly pregnancy and live birth rates.

Evidence summary two

Recommendation Two

Consensus based recommendation