Division of General Surgery, Department of Surgery, Mount Sinai Hospital, Toronto, Ontario, Canada.
Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
JAMA Oncol. 2019 Jul 1;5(7):961-966. doi: 10.1001/jamaoncol.2019.0186.
IMPORTANCE: Chemoradiotherapy (CRT), followed by surgery, is the recommended approach for stage II and III rectal cancer. While CRT decreases the risk of local recurrence, it does not improve survival and leads to poorer functional outcomes than surgery alone. Therefore, new approaches to better select patients for CRT are important. OBJECTIVE: To conduct a phase 2 study to evaluate the safety and feasibility of using magnetic resonance imaging (MRI) criteria to select patients with "good prognosis" rectal tumors for primary surgery. DESIGN, SETTING, AND PARTICIPANTS: Prospective nonrandomized phase 2 study at 12 high-volume colorectal surgery centers across Canada. From September 30, 2014, to October 21, 2016, a total of 82 patients were recruited for the study. Participants were patients newly diagnosed as having rectal cancer with MRI-predicted good prognosis rectal cancer. The MRI criteria for good prognosis tumors included distance to the mesorectal fascia greater than 1 mm; definite T2, T2/early T3, or definite T3 with less than 5 mm of extramural depth of invasion; and absent or equivocal extramural venous invasion. INTERVENTIONS: Patients with rectal cancer with MRI-predicted good prognosis tumors underwent primary surgery. MAIN OUTCOMES AND MEASURES: The primary outcome was the proportion of patients with a positive circumferential resection margin (CRM) rate. Assuming a 10% baseline probability of a positive CRM, a sample size of 75 was estimated to yield a 95% CI of ±6.7%. RESULTS: Eighty-two patients (74% male) participated in the study. The median age at the time of surgery was 66 years (range, 37-89 years). Based on MRI, most tumors were midrectal (65% [n = 53]), T2/early T3 (60% [n = 49]), with no suspicious lymph nodes (63% [n = 52]). On final pathology, 91% (n = 75) of tumors were T2 or greater, 29% (n = 24) were node positive, and 59% (n = 48) were stage II or III. The positive CRM rate was 4 of 82 (4.9%; 95% CI, 0.2%-9.6%). CONCLUSIONS AND RELEVANCE: The use of MRI criteria to select patients with good prognosis rectal cancer for primary surgery results in a low rate of positive CRM and suggests that CRT may not be necessary for all patients with stage II and III rectal cancer. TRIAL REGISTRATION: ISRCTN.com identifier: ISRCTN05107772.
重要性：放化疗（CRT）后手术是 II 期和 III 期直肠癌的推荐治疗方法。虽然 CRT 降低了局部复发的风险，但它并没有改善生存，并且导致比单独手术更差的功能结果。因此，寻找更好的方法来选择接受 CRT 的患者非常重要。
目的：进行一项 2 期研究，以评估使用磁共振成像（MRI）标准选择具有“良好预后”直肠肿瘤的患者进行原发性手术的安全性和可行性。
设计、地点和参与者：在加拿大 12 家高容量结直肠外科中心进行的前瞻性非随机 2 期研究。从 2014 年 9 月 30 日至 2016 年 10 月 21 日，共有 82 名患者参加了这项研究。参与者是新诊断为直肠肿瘤且 MRI 预测为预后良好的直肠肿瘤患者。良好预后肿瘤的 MRI 标准包括距离直肠筋膜大于 1 毫米；明确的 T2、T2/早期 T3 或明确的 T3 伴<5 毫米的外膜浸润深度；以及不存在或不确定的外膜静脉侵犯。
干预措施：具有 MRI 预测良好预后肿瘤的直肠肿瘤患者接受了原发性手术。
主要结果和测量指标：主要结果是阳性环周切缘（CRM）率的比例。假设 CRM 阳性的基线概率为 10%，估计样本量为 75 例，95%CI 为±6.7%。
结果：82 名患者（74%为男性）参加了这项研究。手术时的中位年龄为 66 岁（范围 37-89 岁）。根据 MRI，大多数肿瘤位于中直肠（65%[n=53]）、T2/早期 T3（60%[n=49]），没有可疑的淋巴结（63%[n=52]）。最终病理学检查，91%（n=75）的肿瘤为 T2 或更高，29%（n=24）为淋巴结阳性，59%（n=48）为 II 期或 III 期。CRM 阳性率为 82 例中的 4 例（4.9%；95%CI，0.2%-9.6%）。
结论和相关性：使用 MRI 标准选择具有良好预后的直肠肿瘤患者进行原发性手术可导致 CRM 阳性率较低，提示 CRT 可能不是所有 II 期和 III 期直肠肿瘤患者都必需的。
试验注册：ISRCTN.com 标识符：ISRCTN05107772。
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