Fertility after cancer – 05/18/2023 – Fundamental Science

Cancer is increasingly common worldwide, largely due to increased life expectancy. Although most cases are concentrated in people over 60 years of age, recent analyzes are surprising in showing that the greatest increases in incidence fall on the population aged 20 to 50 years. This means that the current generation of young adults and those to come will have more cancer than the past.

But as occurrences multiply, science improves treatments, reaching survival rates of over 90% for certain tumors. If the next generations will get more cancer, they will likely receive more effective therapies. The concern with the quality of life after treatment becomes, therefore, increasingly important.

Drugs used in most chemotherapy treatments destroy highly proliferative cells, such as tumors. It happens that other cells that propagate quickly, such as those of the mucosa that lines the mouth and those of the hair follicles, can be affected, causing adverse effects such as hair loss and desquamation of the oral mucosa. Chemotherapy can also alter the tissues that produce gametes (eggs and sperm) and levels of sex hormones, with effects on fertility. As a result, children, adolescents and adults who undergo oncological treatments may have compromised ability to generate biological children.

The stock of eggs, determined even in fetal life, begins to decrease even before birth – this ovarian reserve is the main determinant of a woman’s fertility. At the onset of puberty, the ovaries contain 300,000 to 500,000 eggs, contained in cell-lined follicles. Over the years, some of these follicles undergo a maturation process that culminates in the release of one egg per month — ovulation. As menopause approaches, the ovarian reserve is coming to an end.

Exposure to chemotherapy cycles can cause damage to maturing follicles, as these follicular cells proliferate rapidly. In response, still immature follicles are mobilized and begin to grow: this premature activation leaves them subject to the toxic effects of chemotherapy. Thus, girls who have not yet entered puberty may not reach it after chemotherapy treatment, and adolescents and young women may experience early menopause.

In boys and adult men, chemotherapy can affect sperm production, which occurs in the testicles, the body responsible for sex hormones such as testosterone. Some treatments can permanently damage the fertility of prepubertal boys, and negatively impact sperm and sex hormone production in adolescents and young adults.

Several studies show the impact of different chemotherapy protocols on the production of gametes, but it is not always easy to predict the real toxicity that a drug will cause in the fertility of children, adolescents and adults. This effect depends on multiple factors such as dosage, duration of treatment, drug combination, patient age and individual sensitivity to protocols.

Therefore, it is essential that patients are informed about the consequences that chemotherapy can bring to fertility and what are the options to preserve it. Adult women can perform egg cryopreservation before starting treatment. If possible, the eggs can be fertilized and the resulting embryos stored. More recent techniques allow the cryopreservation of ovarian tissue, feasible even for prepubertal girls.

After treatment, the preserved tissue can be transplanted, reestablishing the maturation of the eggs and hormonal cycles. In adolescent and adult men, the most viable option is semen preservation. Techniques currently being developed aim to establish testicular tissue cryopreservation protocols that guarantee the preservation of fertility in boys who have not reached puberty.

Unfortunately, most people undergoing cancer treatment suffer from a lack of information, as well as difficulties in accessing health services for fertility preservation. Supporting the awareness of patients and health professionals on this topic, as well as the development of new research and the popularization of fertility preservation techniques, is essential to guarantee reproductive autonomy and a better quality of life for patients who will undergo treatment. oncology in the coming decades.

Rossana Soletti has a PhD in morphological sciences and is a professor at the Federal University of Rio Grande do Sul.

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