Prediction of tumor response after neoadjuvant chemoradiotherapy in rectal cancer using (18)fluorine-2-deoxy-D-glucose positron emission tomography-computed tomography and serum carcinoembryonic antigen: a prospective study.
To investigate the association between (18)fluorine-2-deoxy-D-glucose positron emission tomography-computed tomography ((18)F-FDG PET/CT) parameters, serum carcinoembryonic antigen (CEA), and tumor response in patients with rectal cancer receiving neoadjuvant chemoradiotherapy (nCRT).



Sixty-four patients with T3-4 and/or node-positive rectal cancer receiving nCRT followed by surgery were prospectively studied. PET/CT was performed before, and in 28 patients, both before and after nCRT. The pre-/post-nCRT maximum standardized uptake (SUVmax) values, differences between pre-/post-nCRT SUVmax (∆SUVmax), response index of SUVmax (RI-SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and CEA were measured. The ability of PET/CT parameters and CEA to predict Mandard's tumor regression grade (TRG) and pathological complete remission (pCR) were evaluated.



31 patients were identified as responders (TRG 1-2), and 19 exhibited pCR. For responders, significant differences were found for ΔSUVmax (24.88 vs. 15.39 g/ml, p = 0.037), RI-SUVmax (0.76 vs. 0.63, p = 0.025), ΔSUVmean (14.43 vs. 8.65 g/ml, p = 0.029), RI-SUVmean (0.77 vs. 0.63, p = 0.011), CEA-pre (6.30 vs. 27.86 μg/L, p < 0.001), CEA-post (2.22 vs. 5.49 μg/L, p = 0.002), ΔCEA (4.08 vs. 23.13 μg/L, p < 0.001), and RI-CEA (0.25 vs. 0.55, p = 0.002). Differences between pCR and non-pCR patients were noted as RI-SUVmean (0.77 vs. 0.65, p = 0.043), MTV-pre (9.87 vs. 14.62 cm(3), p = 0.045), CEA-pre (5.62 vs. 22.27 μg/L, p = 0.002), CEA-post (1.95 vs. 4.72 μg/L, p = 0.001), and ΔCEA (3.68 vs. 17.99 μg/L, p = 0.013). Receiver operating characteristic analysis revealed that RI-SUVmean exhibited the greatest accuracy in predicting responders, whereas CEA-post and ΔCEA exhibited the greatest accuracy in predicting pCR.



(18)F-FDG PET/CT parameters and CEA are accurate tools for predicting tumor response to nCRT in rectal cancer.
Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China.
Qi-Wen
QW
Li
Department of Nuclear Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China.
Rong-Liang
RL
Zheng
Department of Pathology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China.
Yi-Hong
YH
Ling
Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China.
Qiao-Xuan
QX
Wang
Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China.
Wei-Wei
WW
Xiao
Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China.
Zhi-Fan
ZF
Zeng
Department of Nuclear Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China.
Wei
W
Fan
Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China. lilr@sysucc.org.cn.
Li-Ren
LR
Li
Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, No. 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, China. gaoyh@sysucc.org.cn.
Yuan-Hong
YH
Gao
D000293:Adolescent; D000328:Adult; D000368:Aged; D002272:Carcinoembryonic Antigen / Q000097:blood*; D059248:Chemoradiotherapy / Q000379:methods*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods*; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging / Q000628:therapy*; D012007:Rectum / Q000000981:diagnostic imaging; D016896:Treatment Outcome; D055815:Young Adult
D002272:Carcinoembryonic Antigen; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
18F-FDG PET/CT; Carcinoembryonic antigen; Neoadjuvant chemoradiotherapy; Pathological complete remission; Rectal cancer; Tumor regression grade