In this evolving age of personalized medicine, increasing attention has been focused on the genetics of male fertility. As in other disease states, biomarkers are frequently used for diagnosis and stratification, treatment selection, monitoring of disease progression, and establishing patients’ responses to therapy [40]. Although semen analysis testing is still recognized as a surrogate marker of male fertility, the exponential growth of biomarkers derived from proteomics, epigenomics, and genomics has contributed to a new direction of male fertility research. This shift in investigative focus could prove to be the next frontier in directed personalized medicine. However, although many studies have evaluated the genetic basis of male fertility, basic science and translational research have not resulted in a wealth of clinically useful diagnostic tests. Ideally, insights would be gained into genetic susceptibility to various cancer therapies, as well as propensity of an individual to regain reproductive function after completion of cancer treatment.

More than 3,000 genes (about 4 % of human genome) are expressed in the testicles alone, and hundreds of these genes influence reproductive function in humans [41]. Additionally, there are over 4,000 proteins expressed in the seminal plasma. Because of this, significant attention has been focused on the proteomes of the testicles, sperm, seminal fluid, and epididymis [42]. It is thought that these proteins might represent a rich source of potential biomarkers for male fertility [43], and characterization of the reproductive proteome might ultimately lead to significant improvement in the evaluation of the male reproductive tract [44, 45].

This enhanced understanding of fertility markers at the level of the individual might facilitate the development of more comprehensive prognostic models for patients. The benefit of this approach would be potentially enhanced diagnostic capabilities, reduced cost, and personalized fertility treatments that anticipate reproductive success at baseline (before cancer treatment) and post-cancer therapy. This field is still quite young, and it is estimated that more than 1,000 biomarkers would be needed to accurately evaluate male fertility potential [46]. Although much more clinical insight is needed, the implications of a more personalized approach to infertility risk stratification would be an enormously useful tool for clinicians and patients alike.