彭良群 張斌 楊巍 張占東 劉洪興 花亞偉
(鄭州大學(xué)附屬腫瘤醫(yī)院 普外科 河南 鄭州 450008)
·綜 述·
胃癌新輔助化療的研究進(jìn)展
彭良群 張斌 楊巍 張占東 劉洪興 花亞偉
(鄭州大學(xué)附屬腫瘤醫(yī)院 普外科 河南 鄭州 450008)
胃癌;新輔助化療;療效
我國(guó)是胃癌高發(fā)病率的國(guó)家之一,全球40%以上的胃癌新發(fā)病例發(fā)生在我國(guó)[1]。據(jù)我國(guó)2015年癌癥統(tǒng)計(jì)數(shù)據(jù)顯示,胃癌發(fā)生率僅次于肺癌,也是惡性腫瘤死亡的第二大病因[2]。在過(guò)去的幾十年里,我國(guó)胃癌患者的生存率有明顯提高,在大型醫(yī)院,胃癌的5年生存率從40.1%提高到57.6%[3]。近年來(lái),人們對(duì)胃癌的研究逐漸深入,胃癌的治療模式從單一的手術(shù)治療進(jìn)入多學(xué)科團(tuán)隊(duì)的新治療模式[4]。新輔助化療具有降低腫瘤分期、提高R0切除率等優(yōu)勢(shì),成為近幾年研究的熱點(diǎn)。本文就胃癌新輔助化療的研究進(jìn)展做一綜述。
Wilke等[5]于1989年首先報(bào)道了新輔助化療在胃癌中的應(yīng)用,對(duì)腹腔鏡下確診的無(wú)法手術(shù)切除的34例進(jìn)展期胃癌患者給予依托泊苷+阿霉素+順鉑(EAP)方案化療后,有33例患者的腫瘤得到降期,并成功實(shí)施胃癌根治性切除及淋巴結(jié)清掃。英國(guó)醫(yī)學(xué)研究理事進(jìn)行的圍手術(shù)期化療的Ⅲ期臨床試驗(yàn)-MAGIC試驗(yàn)是胃癌新輔助化療的里程碑式的進(jìn)展[6],首次證明了可切除胃、食管下段以及胃食管結(jié)合部癌,圍手術(shù)期給予表阿霉素+順鉑+5-FU(ECF)方案化療,可以改善無(wú)進(jìn)展生存(DFS)以及總生存(OS),而且不增加術(shù)后并發(fā)癥的發(fā)生。在FNCLCC/FFCD試驗(yàn)中,Ychou等[7]證明了以氟尿嘧啶和順鉑的圍手術(shù)期化療方案可顯著提高DFS和OS。但這兩項(xiàng)研究胃癌D2淋巴結(jié)清掃普及率較低,所以,并不足以證實(shí)新輔助化療聯(lián)合胃癌D2根治術(shù)對(duì)患者預(yù)后的價(jià)值。此外,這兩項(xiàng)研究主要針對(duì)食管胃結(jié)合部癌,對(duì)于遠(yuǎn)端胃癌患者的價(jià)值并不能被充分肯定。隨后,多項(xiàng)研究均證實(shí)新輔助化療是安全、有效的[8-9]。國(guó)內(nèi)也開(kāi)展了關(guān)于FOLFOX方案等不同化療方案的臨床研究,取得了良好的成績(jī),積累了一定的經(jīng)驗(yàn)[10]。目前仍有多項(xiàng)關(guān)于胃癌新輔助化療的臨床隨機(jī)對(duì)照試驗(yàn)正在進(jìn)行,包括CRITICS研究、PRODIGY研究、COMPASS研究、COMPASS-D研究以及我國(guó)的RESOLVE研究,均采用了術(shù)后輔助化療作為對(duì)照,這些結(jié)果將可能為胃癌新輔助化療的臨床價(jià)值提供高級(jí)別的循證醫(yī)學(xué)證據(jù)。除了傳統(tǒng)的化療藥物,靶向藥物也開(kāi)始在新輔助化療中應(yīng)用。在2015年歐洲腫瘤大會(huì)(ECC)上報(bào)告了英國(guó)ST03研究結(jié)果,該研究試圖對(duì)比新輔助化療表阿霉素、順鉑+卡培他濱(ECX)聯(lián)合貝伐單抗在可切除胃癌、食管胃結(jié)合部癌和食管癌中的作用,共入組1 063例患者,中位隨訪33個(gè)月,3年總生存率和無(wú)病生存期差異均無(wú)統(tǒng)計(jì)學(xué)意義,增加貝伐單抗后,未見(jiàn)R0切除率和腫瘤反應(yīng)率增加[11]。隨著新輔助化療臨床研究水平的提高,這些研究結(jié)果將為我們提供更高級(jí)別的循證醫(yī)學(xué)證據(jù),新輔助化療將以其獨(dú)特的優(yōu)勢(shì)在胃癌綜合治療中占據(jù)一席之地,我們也期待新輔助化療能進(jìn)一步提高胃癌患者生存率。
2.1 治療前分期及療效評(píng)價(jià)在以循證醫(yī)學(xué)為主導(dǎo)的精準(zhǔn)醫(yī)療背景下,準(zhǔn)確進(jìn)行腫瘤學(xué)評(píng)估,最大程度提高治療前分期的準(zhǔn)確性,是新輔助化療臨床實(shí)踐的重要組成部分。目前最常用的分期手段有超聲內(nèi)鏡(EUS)、計(jì)算機(jī)X射線斷層掃描技術(shù)(CT)、磁共振(MRI)、正電子發(fā)射斷層顯像/X線計(jì)算機(jī)體層成像(PET/CT)及腹腔鏡探查。EUS同時(shí)匯集了胃鏡及超聲的優(yōu)勢(shì),能夠較清楚地判斷腫瘤的浸潤(rùn)深度、淋巴結(jié)轉(zhuǎn)移及鄰近器官受侵情況,尤其是對(duì)少量腹腔積液的診斷[12]。多排螺旋CT(MDCT)可以提供高質(zhì)量圖像,具有強(qiáng)大的影像后處理技術(shù),對(duì)第7版胃癌T分期的準(zhǔn)確率在80%左右,MDCT判定淋巴結(jié)轉(zhuǎn)移有其局限性,對(duì)N分期的準(zhǔn)確率為75%左右,對(duì)肝轉(zhuǎn)移的靈敏度和特異度分別為74%和99%,對(duì)腹膜轉(zhuǎn)移的靈敏度和特異度分別為33%和99%[13-14]。多平面重組(multiplanar reformation,MPR)技術(shù)和雙能量CT更有利于微小病灶的檢出,對(duì)顯示腫瘤的形態(tài)、與鄰近器官的關(guān)系和判斷是否轉(zhuǎn)移有更高的參考價(jià)值[15]。目前,MSCT檢查是胃癌分期的主要方法,但其對(duì)軟組織分辨率較低、具有輻射。MRI軟組織分辨率更高,不存在輻射,具有多序列、多參數(shù)、多方位和三維立體成像,在胃癌分期中有廣闊的前景。磁共振擴(kuò)散加權(quán)成像(diffusion weighted imaging,DWI)可以計(jì)算表觀擴(kuò)散系數(shù)(ADC)值,ADC值在腫瘤細(xì)胞凋亡早期即有增加,與腫瘤生長(zhǎng)速度顯著相關(guān),在淋巴結(jié)轉(zhuǎn)移、放化療療效評(píng)估、預(yù)測(cè)治療效果等方面均有其獨(dú)特的優(yōu)勢(shì)[16]。PET/CT作為一種無(wú)創(chuàng)性功能顯像技術(shù),可彌補(bǔ)解剖性成像的不足,文獻(xiàn)報(bào)道18F-氟代脫氧葡萄糖(18F-FDG)PET/CT對(duì)胃癌診斷的靈敏度、特異度分別為70%~95%和69%~100%,在腫大淋巴結(jié)的判定、遠(yuǎn)處轉(zhuǎn)移、療效評(píng)價(jià)等方面具有一定的優(yōu)勢(shì)[17]。18F-氟代胸苷(18F-FLT)PET/CT可彌補(bǔ)18F-FDG PET/CT的不足,與18F-FDG相比,18F-FLT對(duì)胃癌轉(zhuǎn)移淋巴結(jié)有更高的特異性和準(zhǔn)確性,但靈敏度較低,兩者聯(lián)合可提高診斷準(zhǔn)確性[18]。目前尚無(wú)新輔助化療療效評(píng)價(jià)的金標(biāo)準(zhǔn),臨床上應(yīng)不斷探尋優(yōu)化多種影像學(xué)的評(píng)估方法,綜合評(píng)定療效。
2.2 化療方案的選擇對(duì)于新輔助化療藥物以及方案的選擇,目前還沒(méi)有達(dá)成共識(shí),多主張選擇高效低毒的聯(lián)合化療方案,盡量避免單藥的應(yīng)用。英國(guó)的MAGIC實(shí)驗(yàn)研究及法國(guó)的FNCLCC/FFCD研究肯定了ECF(表柔比星、順鉑、氟尿嘧啶)及氟尿嘧啶和順鉑方案對(duì)胃癌圍手術(shù)期化療的重要價(jià)值[6-7],此后多項(xiàng)高級(jí)別研究證據(jù)證實(shí)了不同化療方案新輔助化療的確切療效[10,19],確立了以氟尿嘧啶類及鉑類為基礎(chǔ)的經(jīng)典聯(lián)合方案,和紫杉類藥物為基礎(chǔ)的聯(lián)合化療方案。AIO FLOT4的Ⅱ期階段數(shù)據(jù)表明,4個(gè)療程的多西他賽、奧沙利鉑、5-FU及亞葉酸鈣(FLOT)方案較3個(gè)療程的ECF方案有更高的病理緩解(CR + SR)(FLOT 29.5%比ECF 15.2%,P=0.036)[20]。S-1作為一種新型的氟尿嘧啶衍生物口服抗癌劑,在胃癌輔助治療中有確切療效[21]。韓國(guó)的PRODIGY研究正在對(duì)T2~3/N+和T4患者新輔助化療生存獲益進(jìn)行評(píng)估,比較D2根治術(shù)前予以多西他賽、順鉑及S-1以及術(shù)后S-1方案、單獨(dú)D2根治術(shù)和D2根治術(shù)+S-1的差異[22]。在我國(guó),由北京大學(xué)腫瘤醫(yī)院組織的多中心隨機(jī)對(duì)照研究(RESONANCE研究)正在進(jìn)行中,旨在證實(shí)S-1+順鉑在新輔助化療受益[23]。近年來(lái),生物靶向藥在胃癌治療中廣泛應(yīng)用,為改善新輔助化療的療效,英國(guó)的STO3研究將貝伐單抗應(yīng)用于新輔助化療,希望提高應(yīng)答率,卻未能如愿[11]。如何實(shí)現(xiàn)在化療前就能鑒別出真正的受益者,實(shí)現(xiàn)個(gè)體化治療,是目前新輔助化療面臨的重要問(wèn)題。隨著對(duì)胃癌分子生物學(xué)行為的深入研究,使胃癌分類從形態(tài)學(xué)轉(zhuǎn)向以分子特征為基礎(chǔ)的分子分型。當(dāng)前基因組學(xué)鑒定了胃癌細(xì)胞系兩個(gè)主要亞型:G-INT和G-DIFF,G-INT亞型患者對(duì)5-氟尿嘧啶和奧沙利鉑更敏感,而G-DIFF亞型患者對(duì)順鉑更敏感[24]。人源化移植瘤模型通過(guò)將新鮮腫瘤組織植于裸鼠皮下成瘤,建立可保留原患者生物學(xué)特性和藥物敏感性的模型[25]。這些發(fā)現(xiàn)將為個(gè)體化的新輔助化療鋪平道路。
2.3 化療療程及手術(shù)時(shí)機(jī)的選擇新輔助化療的療程以及手術(shù)時(shí)機(jī)目前沒(méi)有定論。化療療程過(guò)長(zhǎng)可能會(huì)延誤最佳手術(shù)時(shí)機(jī),而療程過(guò)短可能無(wú)法達(dá)到預(yù)期效果。部分研究者主張可依據(jù)腫瘤分期決定術(shù)前的化療時(shí)間,對(duì)于T2NxM0患者一般化療4~6周,T3及以上患者化療時(shí)間應(yīng)適當(dāng)延長(zhǎng)[26]。這些結(jié)果來(lái)源于晚期胃癌化療的經(jīng)驗(yàn),還需要大型隨機(jī)對(duì)照試驗(yàn)驗(yàn)證。更重要的是化療期間及時(shí)評(píng)價(jià),每4~6周進(jìn)行1次療效評(píng)價(jià),及時(shí)獲得患者對(duì)化療反應(yīng)的信息,隨時(shí)調(diào)整治療策略?;煙o(wú)效者即是預(yù)后較差者,即便行手術(shù)治療也很難達(dá)到根治目標(biāo), 化療結(jié)果是患者的預(yù)后指標(biāo)之一[27]。首方案無(wú)效的患者術(shù)前不建議應(yīng)用二線化療方案,其受益的可能性太低[28]?;熡行д邞?yīng)根據(jù)分期和腫瘤退縮程度選擇手術(shù)時(shí)機(jī),不可一味延長(zhǎng)化療時(shí)間,如已達(dá)到目的就應(yīng)盡早手術(shù),化療時(shí)間不可超過(guò)3個(gè)月[21]。大多數(shù)患者可在化療后3周左右恢復(fù),因此從化療結(jié)束到手術(shù)的間歇期不應(yīng)太長(zhǎng),如果患者身體狀況允許,以3周左右為佳,而僅進(jìn)行1~2個(gè)療程化療者,化療結(jié)束后2周左右即可行手術(shù)治療。近期,COMPASS試驗(yàn)及COMPASS-D試驗(yàn)均采取2×2析因設(shè)計(jì)評(píng)價(jià)2個(gè)和4個(gè)療程新輔助化療方案療效,將為新輔助化療療程的選擇提供確切依據(jù)[29-30]。
2.4 手術(shù)結(jié)合新輔助化療目前,D2根治術(shù)是胃癌標(biāo)準(zhǔn)手術(shù)方式。文獻(xiàn)報(bào)道胃癌D2根治術(shù)致殘率和死亡率分別為20.9%和0.8%[31]。新輔助化療后D2根治術(shù)的可行性和安全性還未得到大型Ⅲ期臨床試驗(yàn)的證實(shí)。在MAGIC Ⅲ期試驗(yàn)中,接受新輔助化療的患者其手術(shù)致殘率和死亡率分別為45.7%和5.6%,而只接受手術(shù)的患者其手術(shù)致殘率和死亡率分別為45.3%和5.9%[6]。在FNCLCC/FFCD Ⅲ期試驗(yàn)中,接受新輔助化療的患者其手術(shù)致殘率和死亡率分別為25.7%和4.6%,而只接受手術(shù)的患者其手術(shù)致殘率和死亡率分別為19.1%和4.5%[7]。在上述兩項(xiàng)試驗(yàn)中,手術(shù)并發(fā)癥發(fā)生率是相似的,但是,在MAGIC試驗(yàn)中大多數(shù)患者未達(dá)到D2程度,在FNCLCC/FFCD試驗(yàn)中,手術(shù)步驟的描述也不準(zhǔn)確。EORTC 40954 Ⅲ期試驗(yàn)對(duì)D2根治術(shù)和術(shù)前給予5-Fu+CDDP在D2根治術(shù)進(jìn)行了比較,兩組中90%的患者進(jìn)行了D2根治術(shù),總致殘率在新輔助化療組為27.1%,高于單純手術(shù)組的16.2%[9]。另一方面,日本的一些Ⅱ期試驗(yàn)證實(shí)即使接受了新輔助化療D2根治術(shù)或擴(kuò)大胃癌根治術(shù)也是安全可行的[32-33]。在LANDSCOPE Ⅱ期試驗(yàn)中,納入80例患者,旨在評(píng)估新輔助化療后腹腔鏡輔助遠(yuǎn)端胃切除術(shù)治療胃癌的效果和安全性[34]。目前,新輔助化療后D2根治術(shù)的可行性和安全性還缺少大型Ⅲ期隨機(jī)對(duì)照試驗(yàn)的支持。
胃癌新輔助化療的益處已在多項(xiàng)前瞻性隨機(jī)對(duì)照臨床試驗(yàn)中證實(shí),該治療模式已被NCCN指南及EMSO指南所推薦在臨床中應(yīng)用。但是,在臨床實(shí)踐中仍面臨諸多問(wèn)題,隨著醫(yī)療技術(shù)的發(fā)展和新型藥物的出現(xiàn),繼續(xù)進(jìn)行一些高質(zhì)量的臨床研究,選擇高效低毒的化療方案,建立完善的療效評(píng)價(jià)標(biāo)準(zhǔn),將是今后胃癌新輔助化療的主要研究方向之一。
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河南省科技攻關(guān)計(jì)劃項(xiàng)目(132102310413)。
花亞偉,E-mail:Huayaweil@163.com。
R 735.2
10.3969/j.issn.1004-437X.2017.05.025
2016-05-02)