Positron emission tomography detection of distant metastatic or synchronous disease in patients with locally advanced rectal cancer receiving preoperative chemoradiation.
BACKGROUND
Patients with locally advanced rectal cancer may present with synchronous distant metastases. Choice of optimal treatment--neoadjuvant chemoradiation versus systemic chemotherapy alone--depends on accurate assessment of distant disease. We prospectively evaluated the ability of [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) to detect distant disease in patients with locally advanced rectal cancer who were otherwise eligible for combined modality therapy (CMT).


METHODS
Ninety-three patients with locally advanced rectal cancer underwent whole-body [18F]FDG PET scanning 2-3 weeks before starting CMT. Sites other than the rectum, mesorectum, or the area along the inferior mesenteric artery were considered distant and were divided into nine groups: neck, lung, mediastinal lymph node (LN), abdomen, liver, colon, pelvis, peripheral LN, and soft tissue. Two nuclear medicine physicians blinded to clinical information used PET images and a five-point scale (0-4) to determine certainty of disease. A score greater than 3 was considered malignant. Confirmation was based on tissue diagnosis, surgical exploration, and subsequent imaging.


RESULTS
At a median follow-up of 34 months, the overall accuracy, sensitivity, and specificity of PET in detecting distant disease were 93.7%, 77.8%, and 98.7% respectively. Greatest accuracy was demonstrated in detection of liver (accuracy = 99.9%, sensitivity = 100%, specificity = 98.8%) and lung (accuracy = 99.9%, sensitivity = 80%, specificity = 100%) disease; PET detected 11/12 confirmed malignant sites in liver and lung. A total of 10 patients were confirmed to have M1 stage disease. All 10 were correctly staged by pre-CMT PET; abdominopelvic computed tomography (CT) scans accurately detected nine of them.


CONCLUSIONS
Baseline PET in patients with locally advanced rectal cancer reliably detects metastatic disease in liver and lung. PET may play a significant role in defining extent of distant disease in selected cases, thus impacting the choice of neoadjuvant therapy.
Nahas
Caio S R
CS
Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
Akhurst
Timothy
T
Yeung
Henry
H
Leibold
Tobias
T
Riedel
Ellen
E
Markowitz
Arnold J
AJ
Minsky
Bruce D
BD
Paty
Philip B
PB
Weiser
Martin R
MR
Temple
Larissa K
LK
Wong
W Douglas
WD
Larson
Steven M
SM
Guillem
José G
JG
D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy*; D016037:Single-Blind Method