Tumor response and survival predicted by post-therapy FDG-PET/CT in anal cancer.
OBJECTIVE
To evaluate the response to therapy for anal carcinoma using post-therapy imaging with positron emission tomography (PET)/computed tomography and F-18 fluorodeoxyglucose (FDG) and to compare the metabolic response with patient outcome.


METHODS
This was a prospective cohort study of 53 consecutive patients with anal cancer. All patients underwent pre- and post-treatment whole-body FDG-PET/computed tomography. Patients had been treated with external beam radiotherapy and concurrent chemotherapy. Whole-body FDG-PET was performed 0.9-5.4 months (mean, 2.1) after therapy completion.


RESULTS
The post-therapy PET scan did not show any abnormal FDG uptake (complete metabolic response) in 44 patients. Persistent abnormal FDG uptake (partial metabolic response) was found in the anal tumor in 9 patients. The 2-year cause-specific survival rate was 94% for patients with a complete vs. 39% for patients with a partial metabolic response in the anal tumor (p = 0.0008). The 2-year progression-free survival rate was 95% for patients with a complete vs. 22% for patients with a partial metabolic response in the anal tumor (p < 0.0001). A Cox proportional hazards model of survival outcome indicated that a complete metabolic response was the most significant predictor of progression-free survival in our patient population (p = 0.0003).


CONCLUSIONS
A partial metabolic response in the anal tumor as determined by post-therapy FDG-PET is predictive of significantly decreased progression-free and cause-specific survival after chemoradiotherapy for anal cancer.
Schwarz
Julie K
JK
Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Siegel
Barry A
BA
Dehdashti
Farrokh
F
Myerson
Robert J
RJ
Fleshman
James W
JW
Grigsby
Perry W
PW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001005:Anus Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000628:therapy; D003131:Combined Modality Therapy / Q000379:methods; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000379:methods*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18