於卵巢正常反應族群進行試管嬰兒療程排卵刺激時添加復乳納可否增加新鮮胚胎移植週期的懷孕率?

Abstract

背景︰世界第一位試管嬰兒Louise Brown於1978年在英國誕生，正式揭開生殖醫學領域的新紀元，催生者是英國劍橋大學羅伯特‧愛德華（Robert G. Edwards），他也榮獲2010年諾貝爾醫學獎的殊榮。自此之後臨床醫師和研究學者為改進不孕患者在體外受精(in vitro fertilization)療程之懷孕率、胚胎著床率、臨床懷孕率的努力便沒有間斷過，對於體外受精和自然受孕過程母體內賀爾蒙表現大有不同早有許多論述。 體外受精在排卵刺激階段造成超生理的(supraphysiological)現象主要表現在雌激素(estrogen)和黃體素(progesterone)此兩種賀爾蒙濃度之上，關於排卵刺激過程血液黃體素濃度提早上升及扳機日(trigger day)濃度過高對新鮮胚胎植入懷孕結果有負面影響已有許多研究討論，不論是扳機當日黃體素濃度閾值或升高時間長短，其結論都相當明確；關於血液雌激素濃度之影響在過去研究雖有著墨，不過對臨床懷孕結果的相關性尚未完全明瞭；而排卵刺激中雌激素和黃體素的濃度有連動關係，進而在雌激素、黃體素、懷孕結果三者間增加了分析的困難度。 本研究主要藉由排除混擾因子(confounding factor)之影響，控制雌激素濃度此操縱變因(independent variable)的前提下來確認雌激素最高濃度和本研究的應變變因(dependent variable)即新鮮胚胎植入懷孕結果之因果關係(causal relationship)。前面提到排卵刺激會造成超生理臨床現象，雌激素濃度過高對子宮內膜在胚胎著床時的容受性有負面影響，那麼降低血液雌激素濃度便是合理因應的介入(intervention)方式。復乳納(Letrozole)，是一種芳香環轉化酶抑制劑(aromatase inhibitor)，芳香環轉化酶在卵巢、大腦、皮膚、骨骼、胎盤和脂肪細胞等人體組織中被發現，作用是把雄激素(androgen)轉化成雌激素，故復乳納能有效地降低體內雌激素的濃度，但不影響雌激素受體作用；最初標榜適應症為病理組織荷爾蒙接受器呈陽性的停經後初期乳癌患者之輔助性治療(adjuvant treatment)，最初在歐盟於1996年上市(美國1997年，台灣1999年)至今已廣為使用，副作用少且安全性高；而復乳納於適應症外做為排卵藥使用最早見於2001年美國著名生殖醫學期刊︰生育和不育(Fertility and Sterility)所刊登之臨床試驗，之後在生殖醫學領域中與復乳納相關的研究論文逐年增加，而在台灣人工生殖臨床醫療也常見以此藥物來協助引導排卵，可知其於生殖醫學領域使用之廣泛性和安全性。 材料與方法︰本研究於2019年4月至2022年1月，於國立臺灣大學醫學院附設醫院婦產部生殖醫學中心進行之前瞻性前導隊列(prospective pilot cohort)研究，並將同時期相同條件之案例作為對照組進行比對分析，最後收錄因不孕症接受體外受精且新鮮胚胎植入的女性共266人，其中107人使用復乳納介入調控雌激素做為實驗組(study group)；另外159人依照原常規治療做為對照組(control group)。 結果︰實驗組及對照組在治療前的特質如年齡、身體質量指數（Body Mass Index, BMI）、不孕症原因、過去懷孕史等皆無明顯差異，治療過程中除實驗組子宮內膜顯著較厚、扳機日黃體素及雌激素濃度顯著較低外，其餘項目在兩組之間皆無統計學上明顯差異。在懷孕率(47.7% vs 38.4%, OR = 1.46, 95% CI = 0.89-2.40, P = 0.13)、胚胎著床率(24.0% vs 17.6%, OR = 1.47, 95% CI = 1.00-2.17, P = 0.03)、臨床懷孕率(40.7% vs 27.7%, OR = 1.76, 95% CI = 1.04-2.95, P < 0.05)、繼續懷孕率(32.7% vs 25.2%, OR = 1.45, 95% CI = 0.84-2.48, P = 0.18)以及流產率(27.1% vs 24.5%, OR = 1.14, 95% CI = 0.47-2.79, P = 0.77)方面實驗組皆比對照組高，除胚胎著床率及臨床懷孕率有統計學上顯著差異外，其它項目未達顯著差異，上述之臨床懷孕率兩組間之p值為0.0492。用次群組分析(subgroup analysis)把兩組中以濾泡數再區分為8-10顆和11-15顆共分為四組，分別兩兩相互比較得出實驗組和對照組中濾泡數目較高的兩個次群組相比，實驗組高濾泡數次群組和對照組高濾泡數次群組相比仍有統計上顯著較高的臨床懷孕率(45.0% vs 25.4%, OR = 2.41, 95% CI = 1.06-5.48, P = 0.04)，而其胚胎著床率(27.8% vs 17.9%, OR = 1.83, 95% CI = 1.00-3.36, p > 0.05)為無顯著差異，其p值為0.0501。對次群組分析使用卡方檢定，並對當中數值可能出現小於5的欄位做費雪爾正確概率檢定(Fisher’s exact test)，上述兩次群組在胚胎著床率和臨床懷孕率皆有顯著差距(p < 0.05)，其中胚胎著床率之p值為0.0483，臨床懷孕率之p值為0.0338，其它次群組間兩兩比較後所有的懷孕結果皆無統計上顯著差異。 結論︰實驗組與對照組皆無卵巢過度刺激症候群(ovarian hyperstimulation syndrome)案例發生，實驗組平均使用復乳納時間為2.9天，且無任何畸胎情況發生，僅有輕微不適如頭痛、噁心等短暫情形被報告，並無中、重度的藥物副作用或過敏現象產生。從本臨床試驗可得知，對卵巢刺激正常反應族群計劃進行體外受精療程時在濾泡晚期使用復乳納共同治療可以增加新鮮胚胎植入週期的臨床懷孕率，進而縮短從嘗試懷孕到活產的時間，亦可能帶來減少冷凍解凍次數對胚胎造成傷害之風險和降低醫療花費等優點。

STUDY QUESTION: Does letrozole co-treatment during controlled ovarian stimulation (COS) in the late follicular phase for in vitro fertilization (IVF) improve the pregnancy rate of fresh embryo transfer (ET) cycle? SUMMARY ANSWER: The clinical pregnancy rate was significantly improved by letrozole co-treatment in the late follicular phase in the fresh ET treatment cycle. WHAT IS KNOWN ALREADY: COS with the treatment of gonadotropins during IVF cycles creates multiple follicles and supraphysiological levels of sex steroids, adversely affecting the endometrium. Letrozole is an effective aromatase inhibitor that decreases estradiol production and is used as adjuvant endocrine therapy for breast cancer. Additionally, it has been used to treat patients suffering from ovulation problems. STUDY DESIGN, SIZE, DURATION: A prospective cohort study including 266 women in IVF (In vitro fertilization)/ICSI (Intracytoplasmic sperm injection) fresh ET cycle with (n = 107) or without letrozole (n = 159) intervention. The letrozole was given daily in the late follicular phase to the day of trigger. The trial was conducted at a tertiary university hospital fertility center from April 2019 to January 2022. PARTICIPANTS/MATERIALS, SETTING, METHODS: The inclusion criteria were patients aged 20 to 45 with regular menstrual cycles who underwent COS fresh ET cycle and whose number of follicles, which size was >10mm, is from 8 to 15 on the trigger day. Patients with preimplantation genetic testing, oocyte recipient treatment cycles, and a history of habitual abortion were excluded. All participants were divided into two groups based on with or without letrozole intervention, a decision made by the research team to which the respective physician belonged. Therefore, this decision can be considered a random process. Univariate analyses were carried out to describe and compare the cycle characteristics with reproductive outcomes. In more detail, subgroup analyses were performed to assess the effect of estradiol level changes. MAIN RESULTS AND THE ROLE OF CHANCE: No statistically significant differences were observed in demographics and baseline characteristics of patients between the study group and control group. On the trigger day, there is a significantly lower estradiol level (pg/ml) (1028.1 ± 392.9 vs 2113.3 ± 844.6; P < 0.01), lower progesterone level (ng/ml) (0.6 ± 0.3 vs 0.8 ± 0.3, P < 0.01) and thicker endometrial lining (mm) (11.4 ± 2.1 vs 10.8 ± 2.1, P = 0.03) in the letrozole group compared with the control group. The study group had a higher pregnancy rate, implantation rate, clinical pregnancy rate, ongoing pregnancy rate, and miscarriage rate, odds ratio (OR) = 1.46, 1.47, 1.76, 1.45, and 1.14, respectively. That reached significant in implantation rate (24.0% vs 17.6%, OR = 1.47, 95% CI = 1.00-2.17, P = 0.03) and in clinical pregnancy rate (40.7% vs 27.7%, OR = 1.76, 95% CI = 1.04-2.95, P < 0.05). We performed subgroup analysis with Pearson’s chi-squared test and Fisher’s exact test based on the follicular number in each group, and the clinical pregnancy rate was still better in the subgroup of the high number in the study group than that in the control group with a static difference (P < 0.05). LIMITATIONS, REASONS FOR CAUTION: There is the potential for selection bias regarding the patients when grouping. In addition, the execution of this trial in a single reproductive center and the small sample size may be of concern. Finally, neither serum androgen levels nor hormone concentrations in follicular fluid were presented in this study, and this would reduce our knowledge of intermediate processes and ovarian follicular microenvironments. However, the effect of letrozole on implantation rate and IVF pregnancy outcome should be evaluated in a larger randomized controlled trial. WIDER IMPLICATIONS OF THE FINDINGS: Lower estradiol levels could benefit the pregnancy outcome of fresh ET, thereby shortening the time to live birth (TTLB), avoiding the embryo damage caused by the freezing process, achieving cost reduction, and reducing the physical burden. TRIAL REGISTRATION NUMBERS: 201810102MINC