In this issue of the Int Braz J Urol, Sposito and colleagues, in a collaborative effort
between the Human Reproduction Unit of Federal University of São Paulo and the Animal
Reproduction Department of University of São Paulo, provide interesting data concerning
antioxidants and oxidants in the semen of testicular germ cell tumor (TGCT) patients
(1).
The authors measured lipid peroxidation, a marker of oxidative stress (OS), and the
levels of enzymatic antioxidants (catalase, glutathione peroxidase, and superoxide
dismutase) in the semen of 26 men with TGTC (12 seminomas and 14 non-seminomas) subjected
to unilateral orchiectomy. Measurements were carried out one month after surgery and
before initiation of adjuvant therapy (if required). Twenty-six healthy men with semen
analysis within normal ranges (WHO 2010 criteria) served as controls. Patients and
controls were matched by age and ejaculatory abstinence. The testicular cancer patients
had lower sperm count than controls, which is expected as spermatogenesis is reduced
by half in adult men with solitary testis due to various causes, including orchiectomy
for testicular cancer (2, 3). More importantly, both cancer groups had higher oxidative
stress markers than controls, albeit not different between seminoma and non-seminoma.
But notably, seminal antioxidant levels were similar between controls and orchiectomized
TGCT patients.
Why is this study being editorialized? First, for the novelty; it is to my knowledge
the first report to investigate oxidative markers and antioxidant levels in semen
of orchiectomized testicular cancer patients. Second, the authors’ results add to
the discussion about the optimal time for sperm cryopreservation. Third, Sposito and
colleagues set the path for future research.
Reactive oxygen species (ROS) are formed during normal cellular metabolism and are
involved in many physiological processes, including the activation of the immune system.
Examples of ROS include superoxide anion (•O2−), hydrogen peroxide (H2O2), the extremely
reactive hydroxyl radical (•OH), and the peroxyl radical (•HO2−) (4). An increase
in ROS levels that exceeds their physiological threshold can induce cellular damage
due to deleterious effects on proteins, lipids, and DNA. Indeed, ROS production in
the male reproductive tract has become a real concern because of their potential toxic
effects on sperm quality and function (4, 5). The extent of damage due to ROS depends
on several factors, including intracellular and extracellular levels of ROS and extent
of anti-oxidation in the environment. Abnormal spermatozoa, polymorphonuclear granulocytes
or both, are primary sources of excessive ROS. The seminal plasma contains natural
antioxidants (AOX), such as vitamins C and E, superoxide dismutase (SOD), glutathione
peroxidase (GPx), and catalase, which counteract the adverse effects of ROS (6). An
imbalance between ROS production and antioxidant defenses leads to oxidative stress
(OS). Lipid peroxidation (LPO) is one end product of OS that causes oxidation of cell
membranes, thus impairing its function. The other is sperm DNA fragmentation (SDF).
The likely result of SDF is infertility (7), but it has been suggested that offspring
generated from such defective sperm are at an increased risk of imprinting disorders
and cancer (8). Oxidative stress is measured by direct and indirect methods. The direct
assays measure ROS levels directly and include chemiluminescence, nitroblue tetrazolium
test, cytochrome C reduction, to cite a few. Indirect methods measure the oxidized
products or their effect at the molecular level and include myeloperoxidase test,
redox potential, lipid peroxidation levels, total antioxidant capacity, SDF testing,
among others. The assays principle, methodology, clinical utility, and drawbacks can
be found elsewhere (5).
Although the literature is rich in studies examining the role of OS and antioxidants
in male infertility, the study of Sposito and colleagues is the first to measure lipid
peroxidation and antioxidant levels in the neat semen of TGCT patients subjected to
orchiectomy (1). Before their study, LPO was investigated only in cryopreserved semen
samples of testicular or non-testicular cancer patients. In frozen-thawed semen from
TGCT men, LPO levels were not different than that of controls (9). The present study
adds to the literature by demonstrating an oxidative imbalance among patients with
TGCT, even after tumor removal.
Equally important is to discuss the clinical implications of Sposito’s et al. findings
for testicular cancer patients banking their semen for fertility preservation. Foremost
among all is perhaps the issue of when to freeze, before or after orchiectomy. On
the one hand, some authors suggest cryopreservation is optimal before orchiectomy
because sperm concentration decreases after surgery (10). On the other hand, others
advocate sperm banking after orchiectomy, as a significant proportion of TGCT men
have high SDF at diagnosis (11). Since cancer induces an overall inflammatory state
with the release of cytokines and other products, it is possible that OS, including
DNA damage, could be mitigated after orchiectomy. In the study of Sposito et al.,
although AOX levels were similar between TGCT patients and controls, LPO levels were
higher in the former, thus indicating that the existing AOX could not fully protect
sperm from the detrimental effect of ROS. Unfortunately, measurements of oxidation
and AOX before orchiectomy were not available, thus precluding conclusion regarding
the optimal time for cryopreservation. Notwithstanding, others have found that TGCT
per se does not increase SDF, and suggest that sperm freezing done either before or
after orchiectomy are equally valid (12, 13). In a recent study evaluating SDF rates
among men with various diagnoses, we found SDF to be elevated in frozen-thawed semen
of men with testicular cancer (14). Still, Spano et al. showed that SDF increases
after both radiotherapy and chemotherapy, irrespective of the type of testicular cancer,
an effect that persists for five years (15). Altogether, the existing evidence suggests
OS is contributory to deterioration of semen quality in TGCT patients. The optimal
time for freezing such specimens, before or after orchiectomy, is yet to be determined,
but it should be carried out, unquestionably, before adjuvant therapy starts.
Lastly, Sposito’s et al. intriguing findings open the possibility for future research.
Measurement of oxidants and AOX before and after orchiectomy could be very informative,
as would be the investigation of AOX added to the freezing media, as a means to overcome
any deleterious effect OS post-thawing, as previously suggested (16-18). While awaiting
for these results, it seems sound to offer sperm banking both before and after orchiectomy,
coupled with the determination of oxidative stress status (if available) or SDF testing,
which is now commonplace (19). Based on the levels of such markers obtained at the
time of cryopreservation, it may be decided later which specimen is safer to use for
Assisted Reproductive Technology.
Sandro C. Esteves, MD, PhD
Medical and Scientific Director
ANDROFERT, Centro de Refêrencia para Reprodução Masculina
Av. Dr. Heitor Penteado, 1464 - Bairro Taquaral
Campinas, SP, 13075-460, Brasil
Fax: +55 19 3294-6992
E-mail: s.esteves@androfert.com.br