Male cancer patient sperm cryopreservation for fertility preservation: 10-year monocentric experience.

BACKGROUND: Sperm cryopreservation, an effective method for preserving male fertility, is very advantageous for men suffering from cancer. Unfortunately, as both physicians and cancer patients are unaware of the possibilities for sperm cryopreservation, the data on evaluation of semen parameters and disposition of cryopreserved samples among Chinese cancer patients are scarce. RESULTS: Male tumours were classified into six major types, germ cell tumours (26 %), haematological neoplasms (28 %), head and neck cancers (19 %), thoracic tumours (4 %), abdominal tumours (10 %), and others (13 %). Haematological neoplasm was the most prevalent cancer among our cohort of patients who opted for sperm banking, followed by germ cell tumours. Patients with germ cell tumours had the lowest pre-thaw and post-thaw seminal sperm concentrations. We separately compared patients with testicular tumours, lymphoma, and leukaemia, and found that leukaemia patients had the lowest pre-thaw sperm concentrations. Most cancer patients (58 %) chose to keep their specimens stored, while 31 % chose to discard the specimens. Over the years, only 13 patients (4 %) returned to use their spermatozoa by assisted reproductive technology. Of the stored samples, patients with germ cell tumours constituted the highest proportion (29.3 %). Moreover, the percentage of haematological neoplasm patients who had no spermatozoa frozen was the highest (46.2 %). CONCLUSIONS: The present data confirm the deleterious impact of various cancers on semen quality. Leukaemia was associated with the worst semen quality and the highest number of semen samples that could not be frozen. We suggest that sperm quality may have decreased even before anti-neoplastic treatment and that sperm banking before treatment should be strongly recommended for cancer patients. A sperm banking programme before gonadotoxic therapy requires close cooperation between assisted reproduction centres and cancer clinics.

RéSUMé: CONTEXTE: Lacryoconservation des spermatozoïdes, méthode efficace pour préserver lafertilité masculine, est très avantageuse pour les hommes atteints de cancer.Malheureusement, comme les médecins et les patients atteints de cancersignorent les possibilités de cryoconservation du sperme, les données surl'évaluation des paramètres spermatiques et le devenir des échantillonscryopréservés parmi les hommes chinois atteints de cancers sont rares. RéSULTATS: Lestumeurs masculines ont été classées en six types principaux, tumeurs germinales(26%), néoplasmes hématologiques (28%), cancers de la tête et du cou (19%),tumeurs thoraciques (4%), les tumeurs abdominales (10%), et les autres (13%).Les néoplasmes hématologiques étaient le cancer le plus répandu parmi notrecohorte de patients qui ont opté pour la mise en banque de leur sperme, suivisdes tumeurs à cellules germinales. Les patients atteints de tumeurs germinalesprésentaient les concentrations de spermatozoïdes pré-congélation etpost-décongélation les plus faibles. Nous avons comparé séparément les patientsatteints de tumeurs testiculaires, de lymphome, et de leucémie, et avonsconstaté que ceux atteins de leucémie présentaient les plus bassesconcentrations de spermatozoïdes pré-congélation. Une majorité de patientsatteints de cancer (58 %) ont choisi de conserver en banque leurs échantillonscongelés, tandis que 31 % ont choisi de jeter leurs échantillons congelés. Aufil des ans, seuls 13 patients (4%) sont revenus pour utiliser leurs spermatozoïdespar Assistance Médicale à la Procréation. Parmi les échantillons mis en banque,ceux des patients atteints de tumeurs germinales constituaient la proportion laplus élevée (29,3 %). Par ailleurs, les patients atteins de cancershématologiques constituaient le pourcentage le plus élevé (46.2%) de patientsqui n'avaient eu aucun spermatozoïde congelé. CONCLUSIONS: Lesdonnées rapportées confirment l'impact délétère des divers cancers sur laqualité du sperme. Les leucémies étaientassociées à la pire qualité du sperme et au plus grand nombre d'échantillons desperme qui ne pouvaient pas être congelés. Nous pensons que la qualité desperme pourrait avoir diminué avant même le traitement antinéoplasique, et quela mise en banque de sperme avant le traitement devrait être fortementrecommandée pour les patients atteints de cancers. Un programme de mise enbanque du sperme avant traitement gonadotoxique nécessite une étroitecoopération entre les centres d'Assistance Médicale à la Procréation et les cliniquesde cancérologie.

COVID-19 epidemic prediction and the impact of public health interventions: A review of COVID-19 epidemic models.

The coronavirus disease outbreak of 2019 (COVID-19) has been spreading rapidly to all corners of the word, in a very complex manner. A key research focus is in predicting the development trend of COVID-19 scientifically through mathematical modelling. We conducted a systematic review of epidemic prediction models of COVID-19 and the public health intervention strategies by searching the Web of Science database. 55 studies of the COVID-19 epidemic model were reviewed systematically. It was found that the COVID-19 epidemic models were different in the model type, acquisition method, hypothesis and distribution of key input parameters. Most studies used the gamma distribution to describe the key time period of COVID-19 infection, and some studies used the lognormal distribution, the Erlang distribution, and the Weibull distribution. The setting ranges of the incubation period, serial interval, infectious period and generation time were 4.9-7 days, 4.41-8.4 days, 2.3-10 days and 4.4-7.5 days, respectively, and more than half of the incubation periods were set to 5.1 or 5.2 days. Most models assumed that the latent period was consistent with the incubation period. Some models assumed that asymptomatic infections were infectious or pre-symptomatic transmission was possible, which overestimated the value of R0. For the prediction differences under different public health strategies, the most significant effect was in travel restrictions. There were different studies on the impact of contact tracking and social isolation, but it was considered that improving the quarantine rate and reporting rate, and the use of protective face mask were essential for epidemic prevention and control. The input epidemiological parameters of the prediction models had significant differences in the prediction of the severity of the epidemic spread. Therefore, prevention and control institutions should be cautious when formulating public health strategies by based on the prediction results of mathematical models.

Why does the spread of COVID-19 vary greatly in different countries? Revealing the efficacy of face masks in epidemic prevention.

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is highly contagious, and the coronavirus disease 2019 (COVID-19) pandemic caused by it has forced many countries to adopt 'lockdown' measures to prevent the spread of the epidemic through social isolation of citizens. Some countries proposed universal mask wearing as a protection measure of public health to strengthen national prevention efforts and to limit the wider spread of the epidemic. In order to reveal the epidemic prevention efficacy of masks, this paper systematically evaluates the experimental studies of various masks and filter materials, summarises the general characteristics of the filtration efficiency of isolation masks with particle size, and reveals the actual efficacy of masks by combining the volume distribution characteristics of human exhaled droplets with different particle sizes and the SARS-CoV-2 virus load of nasopharynx and throat swabs from patients. The existing measured data show that the filtration efficiency of all kinds of masks for large particles and extra-large droplets is close to 100%. From the perspective of filtering the total number of pathogens discharged in the environment and protecting vulnerable individuals from breathing live viruses, the mask has a higher protective effect. If considering the weighted average filtration efficiency with different particle sizes, the filtration efficiencies of the N95 mask and the ordinary mask are 99.4% and 98.5%, respectively. The mask can avoid releasing active viruses to the environment from the source of infection, thus maximising the protection of vulnerable individuals by reducing the probability of inhaling a virus. Therefore, if the whole society strictly implements the policy of publicly wearing masks, the risk of large-scale spread of the epidemic can be greatly reduced. Compared with the overall cost of social isolation, limited personal freedoms and forced suspension of economic activities, the inconvenience for citizens caused by wearing masks is perfectly acceptable.