The role of dual-time combined 18-fluorodeoxyglucose positron emission tomography and computed tomography in the staging and restaging workup of locally advanced rectal cancer, treated with preoperative chemoradiation therapy and radical surgery.
OBJECTIVE
In patients with locally advanced rectal cancer (LARC) staging and, after preoperative chemo-radiation therapy (CRT), restaging workup could be useful to tailor therapeutic approaches. Fluorine-18-fluorodeoxyglucose positron emission tomography ([(18)F]FDG-PET) is a promising tool for monitoring the effect of antitumor therapy. This study was aimed to evaluate the possible role of dual time sequential FDG-PET scans in the staging and restaging workup of LARC.


METHODS
Eighty-seven consecutive patients with LARC were enrolled. CRT consisted of external-beam intensified radiotherapy (concurrent boost), with concomitant chemotherapy PVI 5-FU (300 mg/m(2)/day) followed 8-10 weeks later by surgery. All patients underwent [(18)F]FDG-PET/CT before and 5-6 weeks later after the completion of CRT. Measurements of FDG uptake (SUV(max)), and percentage of SUV(max) difference (Response Index = RI) between pre- and post-CRT [(18)F]FDG-PET scans were evaluated.


RESULTS
Six of 87 patients were excluded due to protocol deviation. Following CRT, 40/81 patients (49%) were classified as responders according to Mandard's criteria (TRG1-2). The mean pre-CRT SUV(max) was significantly higher than post-CRT (15.8, vs 5.9; p < 0.001). The mean RI was significantly higher in responders than in nonresponder patients (71.3% vs 38%; p = 0.0038). Using a RI cut-off of 65% for defining response to therapy, the following parameters have been obtained: 84.5% sensitivity, 80% specificity, 81.4% positive predictive value, 84.2% negative predictive value, and 81% overall accuracy.


CONCLUSIONS
These results suggest the potential role of [(18)F]FDG-PET in the restaging workup after preoperative CRT in LARC. RI seems the best predictor to identify CRT response.
Capirci
Carlo
C
Department of Radiotherapy, State Hospital, Rovigo, Italy. capirci.carlo@azisanrovigo.it
Rubello
Domenico
D
Pasini
Felice
F
Galeotti
Fabrizio
F
Bianchini
Enzo
E
Del Favero
Giuseppe
G
Panzavolta
Riccardo
R
Crepaldi
Giorgio
G
Rampin
Lucia
L
Facci
Enzo
E
Gava
Marcello
M
Banti
Elena
E
Marano
Gianfranco
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage; D005260:Female; D019788:Fluorodeoxyglucose F18; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods; D009367:Neoplasm Staging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D012074:Remission Induction / Q000379:methods; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
D000964:Antimetabolites, Antineoplastic; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005472:Fluorouracil