Early FDG PET response assessment of preoperative radiochemotherapy in locally advanced rectal cancer: correlation with long-term outcome.
OBJECTIVE
The aim of the present study is to prospectively evaluate the prognostic value of previously defined [(18)F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) criteria of early metabolic response in patients with locally advanced rectal cancer (LARC) after long-term follow-up.


METHODS
Forty-two patients with poor prognosis LARC underwent three biweekly courses of chemotherapy with oxaliplatin, raltitrexed and 5-fluorouracil modulated by levofolinic acid during pelvic radiotherapy. FDG PET studies were performed before and 12 days after the beginning of the chemoradiotherapy (CRT) treatment. Total mesorectal excision (TME) was carried out 8 weeks after completion of CRT. A previously identified cutoff value of ≥52 % reduction of the baseline mean FDG standardized uptake value (SUV(mean)) was applied to differentiate metabolic responders from non-responders and correlated to tumour regression grade (TRG) and survival.


RESULTS
Twenty-two metabolic responders showed complete (TRG1) or subtotal tumour regression (TRG2) and demonstrated a statistically significantly higher 5-year relapse-free survival (RFS) compared with the 20 non-responders (86 vs 55 %, p = .014) who showed TRG3 and TRG4 pathologic responses. A multivariate analysis demonstrated that early ∆SUV(mean) was the only pre-surgical parameter correlated to the likelihood of recurrence (p = .05).


CONCLUSIONS
This study is the first prospective long-term evaluation demonstrating that FDG PET is not only an early predictor of pathologic response but is also a valuable prognostic tool. Our results indicate the potential of FDG PET for optimizing multidisciplinary management of patients with LARC.
Department of Gastrointestinal Medical Oncology, Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione "G. Pascale", Naples, Italy. a.avallone@istitutotumori.na.it
Antonio
A
Avallone
Luigi
L
Aloj
Corradina
C
Caracò
Paolo
P
Delrio
Biagio
B
Pecori
Fabiana
F
Tatangelo
Nigel
N
Scott
Rossana
R
Casaretti
Francesca
F
Di Gennaro
Massimo
M
Montano
Lucrezia
L
Silvestro
Alfredo
A
Budillon
Secondo
S
Lastoria
D000328:Adult; D000368:Aged; D059248:Chemoradiotherapy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D057234:Preoperative Period; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery / Q000628:therapy*; D012074:Remission Induction; D016896:Treatment Outcome
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18