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Authors
Advisor(s)
Abstract(s)
Introdução
A investigação em oncologia tem proporcionado significativos avanços ao nível do diagnóstico
precoce e tratamento da doença oncológica, contribuindo para um número crescente de
sobreviventes de cancro em idade pré-púbere e reprodutiva. Por outro lado, as abordagens
terapêuticas podem ser tóxicas para os órgãos reprodutivos e conduzir a infertilidade.
Adicionalmente, os efeitos causados pela insuficiência ovárica podem aumentar o risco de
osteoporose e doença cardíaca, assim como causar sintomas da menopausa. A
Criopreservação de Tecido Ovárico é uma técnica promissora, que pode ser proposta a
doentes em risco, uma vez que permite restaurar a função endócrina ovárica e a capacidade
reprodutiva.
Objetivos
O objetivo principal desta dissertação é analisar as possíveis aplicações clínicas do tecido
ovárico criopreservado em doentes oncológicas.
Metodologia
Foi realizada uma ampla pesquisa bibliográfica, com recurso à base de dados PubMed. Foram
usadas as seguintes palavras-chave: “ovarian tissue cryopreservation”, “cryopreservation of
ovarian tissue”, “fertility preservation” e “cancer”. Adicionalmente, foram consultados
comunicados, guidelines e pareceres de entidades de relevo na área. Após a análise do
material recolhido, foi realizada uma revisão descritiva.
Resultados e Discussão
A criopreservação de tecido ovárico é um método considerado ainda experimental pela
maioria das sociedades. É uma técnica que não exige a existência de um dador de esperma
nem a realização de estimulação ovárica, e é a única opção disponível para raparigas prépúberes e para casos em que não se pode atrasar o início do tratamento. Atualmente, já
foram notificadas mais de 130 gravidezes após recurso ao método e em mais de 95% casos
ocorreu recuperação da função ovárica após o transplante. Estima-se que a taxa de
nascimentos e gravidezes é cerca de 37,7%, sendo comparável a outros métodos de
preservação da fertilidade. O facto de o tecido ovárico transplantado permitir restaurar a
função endócrina ovárica tem evocado novas perspetivas de utilização do tecido
criopreservado, nomeadamente a terapia hormonal de substituição baseada em tecido
celular, em detrimento da terapia hormonal de substituição farmacológica, e a possibilidade
de o método ser proposto para adiar a menopausa em mulheres saudáveis. Adicionalmente,
pode ser uma abordagem atrativa para induzir a puberdade em jovens pré-puberes, existindo,
já, relato de dois casos de sucesso. No entanto, o procedimento levanta algumas
preocupações e os principais desafios da técnica surgem sobretudo numa fase pós-transplante, nomeadamente o restabelecimento da vascularização e o risco de reimplantação
de células malignas.
Conclusão
A Criopreservação de Tecido Ovárico tem sido amplamente aplicada na preservação da
fertilidade em doentes oncológicas, e mais recentemente, tem sido discutida como
alternativa para adiar a menopausa e induzir a puberdade. No entanto, é evidente a
necessidade de maior investigação para otimizar e estandardizar protocolos na realização da
técnica; assim como, melhorar os métodos de pesquisa de células malignas e de
revascularização do tecido enxertado.
Introduction Research in oncology has provided significant advances in the diagnosis and treatment of oncological disease, which leads to an increasing number of cancer survivors in prepubertal and reproductive age. While treatment approaches are improving, they may also lead to infertility, as it can be harmful to germinative cells. In addition to fertility loss, effects caused by ovarian failure can be responsible for increased risks of osteoporosis and heart disease and induce menopausal symptoms. Ovarian Tissue Cryopreservation is a promising technique that can be proposed to patients at risk, since it allows restoring ovarian endocrine function and reproductive capacity. Objectives The main objective of this dissertation is to analyze the possible clinical applications of cryopreserved ovarian tissue in cancer patients. Methods A wide bibliographic search was carried out, using the PubMed database. The following keywords were used: “ovarian tissue cryopreservation”, “cryopreservation of ovarian tissue”, “fertility preservation” and “cancer”. Additionally, communications, guidelines and recommendations from relevant related societies were consulted. Afterwards, a descriptive review was carried out. Results and Discussion Ovarian tissue cryopreservation is still considered an experimental technique by most societies. It does not require a sperm donor or ovarian stimulation, and it is the only option available to prepubertal girls and patients who do not have enough time to undergo another fertility preservation method. Until today, the technique has enabled the birth of more than 130 healthy babies worldwide and the restoration of ovarian endocrine function in 95% of the patients. The pregnancy and live birth rate is reported to be about 37,7%. As it allows to restore the ovarian function, some possible new perspectives on the use of cryopreserved tissue have been evoked, mainly the hormone replacement therapy based on cell tissue, at the expense of pharmacological hormone replacement therapy, and the possibility of using it to postpone menopause in healthy women. Additionally, cryopreservation of ovarian tissue can also be a potential physiological approach to induce puberty in prepubertal girls. At this date, two cases have been reported. Nevertheless, the procedure arouses some concerns and the main challenges of the technique arise mainly in the post-transplant phase and include the restoration of vascularization and the risk of malignant cells reimplantation. Conclusion Ovarian Tissue Cryopreservation has been applied effectively to preserve fertility in cancer patients and, more recently, it has been discussed as an alternative to postpone menopause and induce puberty. However, further research to optimize and standardize cryopreservation is necessary; as well as to improve methods of searching for malignant cells and revascularizing the grafted tissue
Introduction Research in oncology has provided significant advances in the diagnosis and treatment of oncological disease, which leads to an increasing number of cancer survivors in prepubertal and reproductive age. While treatment approaches are improving, they may also lead to infertility, as it can be harmful to germinative cells. In addition to fertility loss, effects caused by ovarian failure can be responsible for increased risks of osteoporosis and heart disease and induce menopausal symptoms. Ovarian Tissue Cryopreservation is a promising technique that can be proposed to patients at risk, since it allows restoring ovarian endocrine function and reproductive capacity. Objectives The main objective of this dissertation is to analyze the possible clinical applications of cryopreserved ovarian tissue in cancer patients. Methods A wide bibliographic search was carried out, using the PubMed database. The following keywords were used: “ovarian tissue cryopreservation”, “cryopreservation of ovarian tissue”, “fertility preservation” and “cancer”. Additionally, communications, guidelines and recommendations from relevant related societies were consulted. Afterwards, a descriptive review was carried out. Results and Discussion Ovarian tissue cryopreservation is still considered an experimental technique by most societies. It does not require a sperm donor or ovarian stimulation, and it is the only option available to prepubertal girls and patients who do not have enough time to undergo another fertility preservation method. Until today, the technique has enabled the birth of more than 130 healthy babies worldwide and the restoration of ovarian endocrine function in 95% of the patients. The pregnancy and live birth rate is reported to be about 37,7%. As it allows to restore the ovarian function, some possible new perspectives on the use of cryopreserved tissue have been evoked, mainly the hormone replacement therapy based on cell tissue, at the expense of pharmacological hormone replacement therapy, and the possibility of using it to postpone menopause in healthy women. Additionally, cryopreservation of ovarian tissue can also be a potential physiological approach to induce puberty in prepubertal girls. At this date, two cases have been reported. Nevertheless, the procedure arouses some concerns and the main challenges of the technique arise mainly in the post-transplant phase and include the restoration of vascularization and the risk of malignant cells reimplantation. Conclusion Ovarian Tissue Cryopreservation has been applied effectively to preserve fertility in cancer patients and, more recently, it has been discussed as an alternative to postpone menopause and induce puberty. However, further research to optimize and standardize cryopreservation is necessary; as well as to improve methods of searching for malignant cells and revascularizing the grafted tissue
Description
Keywords
Cancro Criopreservação de Tecido Ovárico Preservação da Fertilidade