Prediction of neoadjuvant radiation chemotherapy response and survival using pretreatment [(18)F]FDG PET/CT scans in locally advanced rectal cancer.
OBJECTIVE
The aim of this study was to investigate metabolic and textural parameters from pretreatment [(18)F]FDG PET/CT scans for the prediction of neoadjuvant radiation chemotherapy response and 3-year disease-free survival (DFS) in patients with locally advanced rectal cancer (LARC).


METHODS
We performed a retrospective review of 74 patients diagnosed with LARC who were initially examined with [(18)F]FDG PET/CT, and who underwent neoadjuvant radiation chemotherapy followed by complete resection. The standardized uptake value (mean, peak, and maximum), metabolic volume (MV), and total lesion glycolysis of rectal cancer lesions were calculated using the isocontour method with various thresholds. Using three-dimensional textural analysis, about 50 textural features were calculated for PET images. Response to neoadjuvant radiation chemotherapy, as assessed by histological tumour regression grading (TRG) after surgery and 3-year DFS, was evaluated using univariate/multivariate binary logistic regression and univariate/multivariate Cox regression analyses.


RESULTS
MVs calculated using the thresholds mean standardized uptake value of the liver + two standard deviations (SDs), and mean standard uptake of the liver + three SDs were significantly associated with TRG. Textural parameters from histogram-based and co-occurrence analysis were significantly associated with TRG. However, multivariate analysis revealed that none of these parameters had any significance. On the other hand, MV calculated using various thresholds was significantly associated with 3-year DFS, and MV calculated using a higher threshold tended to be more strongly associated with 3-year DFS. In addition, textural parameters including kurtosis of the absolute gradient (GrKurtosis) were significantly associated with 3-year DFS. Multivariate analysis revealed that GrKurtosis could be a prognostic factor for 3-year DFS.


CONCLUSIONS
Metabolic and textural parameters from initial [(18)F]FDG PET/CT scans could be indexes to assess tumour heterogeneity for the prediction of neoadjuvant radiation chemotherapy response and recurrence in LARC.
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Ji-In
JI
Bang
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Seunggyun
S
Ha
Department of Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Sung-Bum
SB
Kang
Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Keun-Wook
KW
Lee
Department of Pathology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Hye-Seung
HS
Lee
Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Jae-Sung
JS
Kim
Department of Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Heung-Kwon
HK
Oh
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea. debobkr@gmail.com.|Cancer Research Institute, Seoul National University, Seoul, Republic of Korea. debobkr@gmail.com.
Ho-Young
HY
Lee
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Sang Eun
SE
Kim
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D000069287:Capecitabine / Q000008:administration & dosage; D059248:Chemoradiotherapy / Q000379:methods*; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000737:chemistry; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D021621:Imaging, Three-Dimensional; D002955:Leucovorin / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D020360:Neoadjuvant Therapy / Q000379:methods*; D049268:Positron-Emission Tomography; D011379:Prognosis; D016016:Proportional Hazards Models; D019275:Radiopharmaceuticals / Q000737:chemistry; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality* / Q000628:therapy; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000069287:Capecitabine; D002955:Leucovorin; D005472:Fluorouracil
18F-Fluorodeoxyglucose; Metabolic volume; Positron-emission tomography; Prognostic parameter; Tumour heterogeneity; Tumour stage