摘要
The management of rectal cancer has evolved significantly in the last few decades.Significant improvements in local disease control were achieved in the 1990s,with the introduction of total mesorectal excision and neoadjuvant radiotherapy.Level 1 evidence has shown that,with neoadjuvant chemoradiation therapy(CRT)the rates of local recurrence can be lower than 6%and,as a result,neoadjuvant CRT currently represents the accepted standard of care.This approach has led to reliable tumor down-staging,with 15–27%patients with a pathological complete response(pCR)—defined as no residual cancer found on histological examination of the specimen.Patients who achieve pCR after CRT have better long-term outcomes,less risk of developing local or distal recurrence and improved survival.For all these reasons,sphincter-preserving procedures or organ-preserving options have been suggested,such as local excision of residual tumor or the omission of surgery altogether.Although local recurrence rate has been stable at 5–6%with this multidisciplinary management method,distal recurrence rates for locally-advanced rectal cancers remain in excess of 25%and represent the main cause of death in these patients.For this reason,more recent trials have been looking at the administration of full-dose systemic chemotherapy in the neoadjuvant setting(in order to offer early treatment of disseminated micrometastases,thus improving control of systemic disease)and selective use of radiotherapy only in non-responders or for low rectal tumors smaller than 5 cm.
在过去几十年里,直肠癌的治疗已有了很大的进展,其中最为显著的要属20世纪90年代全直肠系膜切除术(TME)的问世和新辅助放化疗(CRT)的应用。临床Ⅰ级证据显示,新辅助放化疗(CRT)可使局部复发率降至6%以下,CRT也就此成为了目前直肠癌的标准治疗模式。CRT可使肿瘤降期,其中15%–27%的患者可以获得病理完全缓解(pCR),意味着CRT后在组织学标本中无任何肿瘤残留。CRT后获得pCR的患者预后良好,局部复发和远处转移风险下降,生存时间延长。因此,积极保留括约肌或保留器官的手术方式如局部切除术在直肠癌治疗中得以更多的应用,甚至非手术治疗也成为可能。尽管多学科综合治疗可使局部进展期直肠癌的局部复发率稳定在5%–6%,但其远处转移率却仍然高达25%以上,这也是患者的主要死因。因此,最近一些研究采用新辅助全量系统化疗以早期治疗远处微转移灶,从而提高肿瘤的系统控制率,仅对化疗无应答者或低位直肠癌(距肛缘不足5 cm)进行术前放疗。
