Arslan Esra, Aksoy Tamer, Gürsu Rıza Umar, Dursun Nevra, Çakar Ekrem, Çermik Tevfik Fikret
University of Health and Sciences, İstanbul Training and Research Hospital, Clinic of Nuclear Medicine, İstanbul, Turkey
University of Health and Sciences, İstanbul Training and Research Hospital, Clinic of Medical Oncology, İstanbul, Turkey
Mol Imaging Radionucl Ther. 2020 Feb 17;29(1):17-24. doi: 10.4274/mirt.galenos.2019.33866.
Prognostic effect of KRAS mutation and side of tumor in colorectal cancer is a highly controversial subject. Therefore, we evaluated the association between FDG uptake pattern in F-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (F-FDG PET/CT) imaging and KRAS mutation and tumor localization in patients with a diagnosis of colon cancer and assessed the effects of these three factors on prognosis and survival.
Eighty-three patients with colorectal cancer were retrospectively included in this study. F-FDG PET/CT study was performed for pretreatment staging. The maximum standardized uptake value (SUV) of the primary tumor and survival data of patients were compared between groups. KRAS mutations were detected with the help of real-time Polymerase Chain Reaction technique through genomic DNA extracted from paraffin-embedded tumor tissue blocks. Tumor lesions with potential KRAS mutations were classified as mutant KRAS and wild type.
Twenty five patients were female while 58 were male. The mean age of the patients was 59.8±11.3 years. Mean follow-up was 35.5±18.9 months. Primary tumor was localized in the left colon in 83.1% of patients and in the right colon in 16.9%. KRAS mutation was detected in 54.2% (n=45) of patients. Mean SUV of patients with primary tumor was estimated to be 21.1±9.1 (range= 6.0-47.5). Mean tumor SUV of patients with a KRAS mutation (24.0±9.0) was found to be significantly higher than those without KRAS mutation (17.7±8.2) (p=0.001). Mean survival was significantly shorter in patients with locoregional nodal metastasis than in patients without locoregional nodal metastasis as well as in patients with distant nodal metastasis than in patients without distant nodal metastasis and in patients with organ metastasis in initial PET/CT than in patients without organ metastasis. Also, mean survival was nearly statistically-significantly shorter in patients with tumors located in left colon (34.2±19.4) than in right colon (43.2±14.6) (p=0.059). However, we found no significant impact of KRAS mutation on survival.
In our study, we found that tumor localization had no significant effect on prognosis in patients with colon cancer. On the other hand, FDG uptake was observed to be higher in the presence of KRAS mutation and it was concluded that coexistence of KRAS mutation with higher SUV is a negative prognostic factor.
KRAS突变及肿瘤部位对结直肠癌预后的影响是一个极具争议的话题。因此，我们评估了F-氟-2-脱氧葡萄糖正电子发射断层扫描/计算机断层扫描（F-FDG PET/CT）成像中FDG摄取模式与KRAS突变及肿瘤定位之间的关联，并评估了这三个因素对结肠癌患者预后和生存的影响。
本研究回顾性纳入了83例结直肠癌患者。进行F-FDG PET/CT检查以进行治疗前分期。比较了原发肿瘤的最大标准化摄取值（SUV）及患者的生存数据。借助实时聚合酶链反应技术，通过从石蜡包埋的肿瘤组织块中提取的基因组DNA检测KRAS突变。具有潜在KRAS突变的肿瘤病变分为KRAS突变型和野生型。
25例患者为女性，58例为男性。患者的平均年龄为59.8±11.3岁。平均随访时间为35.5±18.9个月。83.1%的患者原发肿瘤位于左半结肠，16.9%位于右半结肠。54.2%（n = 45）的患者检测到KRAS突变。原发肿瘤患者的平均SUV估计为21.1±9.1（范围 = 6.0 - 47.5）。发现KRAS突变患者的平均肿瘤SUV（24.0±9.0）显著高于无KRAS突变患者（17.7±8.2）（p = 0.001）。局部区域淋巴结转移患者的平均生存期明显短于无局部区域淋巴结转移患者，远处淋巴结转移患者的平均生存期明显短于无远处淋巴结转移患者，初始PET/CT检查时有器官转移患者的平均生存期明显短于无器官转移患者。此外，位于左半结肠的肿瘤患者（34.2±19.4）的平均生存期比位于右半结肠的患者（43.2±14.6）短，差异接近具有统计学意义（p = 0.059）。然而，我们发现KRAS突变对生存无显著影响。
在我们的研究中，我们发现肿瘤定位对结肠癌患者的预后无显著影响。另一方面，观察到KRAS突变时FDG摄取更高，并且得出结论，KRAS突变与更高的SUV共存是一个不良预后因素。
