Although oncologic testicular sperm extraction (onco-TESE) has been increasingly practiced, the evidence of onco-TESE performed in patients with testicular cancer, especially bilateral testicular cancer, is insufficient. We present a challenging case of onco-TESE from a single cancerous testis with a metachronous bilateral testicular tumor that was detected at 5 years after orchiectomy of the contralateral testis; this procedure resulted in the successful retrieval of normal sperms, which were used for intracytoplasmic sperm injection (ICSI).

Although testicular cancer is one of the most common malignancies in men of reproductive age [1], the treatment modalities are often detrimental to male fertility [2]. Therefore, fertility preservation is often a critical issue among young male patients with testicular cancer. Currently, sperm cryopreservation before gonadotoxic cancer treatment is only the established procedure for fertility preservation. For patients with nonobstructive azoospermia, TESE is a commonly selected method to directly retrieve seminiferous tubules from testicular tissue. Considering the emphasis on sustaining the quality of life of cancer survivors in the last few decades, onco-TESE has been increasingly practiced since its introduction by Schrader in 2003 [3]. Testicular cancer patients more frequently need onco-TESE due to the higher risk of azoospermia. The incidence rate of azoospermia before any sterilization treatment is 5–10% among testicular cancer patients, which is significantly higher than the 1% in the normal population [4–6].

The methodology for onco-TESE in testicular cancer patients has not been established. Onco-TESE for testicular cancer patients is often challenging because the sample needs to be retrieved from noncancerous tissue that has been separated from cancerous tissue. The evidence of using sperms from noncancerous tissue in cancerous testes has not been sufficiently accumulated. To our knowledge, only 27 cases of onco-TESE in testicular cancer patients have been reported in the literature [3, 6–11]. This case report showed the result of onco-TESE with bilateral testicular cancer, which is more challenging than one with unilateral cancer. Most testicular cancers occur unilaterally, and the incidence rate of bilateral cancer is only 0.5–5% [12]. Among bilateral testicular cancer cases, approximately 35% are identified as synchronous and 65% are metachronous [13]. Our case is a metachronous type occurring in his residual testis 5 years after the first orchiectomy in the contralateral testis. In terms of occurrence patterns, onco-TESE in testicular cancer can be categorized into three types: (i) TESE from the contralateral normal testis at the time of orchiectomy for a unilateral testicular tumor, (ii) TESE from the healthier side of a testis with a synchronous bilateral testicular tumor, and (iii) TESE from a single testis with a metachronous testicular tumor in patient who formerly underwent orchiectomy. The 27 reported cases of onco-TESE in testicular cancer included 20 cases of type (i), 4 cases of type (ii), and 3 cases of type (iii). Our case presents the fourth experience of type (iii) [3, 6–11].

It is noteworthy that the normal sperms were successfully harvested and used for multiple ICSI cycles in this case, because the outcomes of onco-TESE, including the success rates of sperm retrieval, use, conception, and pregnancy, have not been sufficiently documented. Among the reported cases of onco-TESE, the success rate of sperm retrieval was 45% in the azoospermia patents with any type of cancer and 59% (16 of 27 cases) in those with testicular cancer [3, 6–11]. These rates do not seem significantly lower than the successful retrieval rates of 30–60% for TESE in non-cancer patients [14]. The usage/pregnancy rates after onco-TESE remain even more unclear because of the limited number of cases and short period of observation. Among 16 reported cases of successful sperm retrieval with onco-TESE in testicular cancer patients, only 5 cases underwent ICSI, and 4 cases resulted in pregnancy [7–10]. Our case is the third documented case of bilateral metachronous testicular cancer resulting in sperm use for ICSI, and the first case of a nonseminomatous testicular cancer with such an occurrence pattern and actual use of preserved sperms [8, 9].

The safety of using sperms retrieved from cancerous testis in terms of fetal health also remains unclear. Only a few cases have reported birth of healthy baby with onco-TESE from cancerous testis, including one case with bilateral testicular cancer [7–10]. Although a previous study has reported that smaller tumor diameter and longer distance from tumor margin were positive predictors of favorable spermatogenesis with onco-TESE in testicular cancer patients [15], it is indeterminate whether onco-TESE with such favorable spermatogenesis is secure. Accumulative evidences for the safety of onco-TESE are necessary.

The present case also suggested the possibility of sperm retrieval with onco-TESE despite unfavorable Johnsen score. Although the Johnsen score in this case was 6, indicating maturation arrest, normal sperms were obtained from the cryo-thawed testicular tissue. This discrepancy occurs possibly because the onco-TESE was performed with the macroscopic detection of normal testicular tissue. Conversely, microdissection TESE (MD-TESE) that enables sampling from microscopically healthier seminiferous tubules may be recommended for onco-TESE. Additionally, this case also showed an inconsistent result between histological and clinical information: the wide intraseminiferous lumen suggesting obstruction of the tubules in contrast to the clinical diagnosis of non-obstructive azoospermia with the elevated sexual hormones. Although it is difficult to clarify the reason for this inconsistency, this case may imply that such dilated intraseminiferous lumen is caused by partial obstruction of the tubules in the microenvironment of cancerous testis in azoospermic patients with testicular cancer.

In conclusion, our case presented that motile normal sperms were successfully retrieved from preserved testicular tissue and used for multiple ICSI attempts. Although successful pregnancy has not yet been achieved in this case, the successful experience of sperm retrieval from a residual single testis in a patient with bilateral and metachronous nonseminoma implies the effectiveness of onco-TESE in challenging cases.