PET/CT and histopathologic response to preoperative chemoradiation therapy in locally advanced rectal cancer.
OBJECTIVE
The objective of this study was to investigate the possibility of using positron emission tomography/computer tomography to predict the histopathologic response in locally advanced rectal cancer treated with preoperative chemoradiation.


METHODS
The study included 30 patients with locally advanced rectal adenocarcinoma treated with a combination of radiotherapy and concurrent Uftoral (uracil, tegafur) and leucovorine. All patients were evaluated by positron emission tomography/computer tomography scan seven weeks after end of chemoradiation, and the results were compared to histopathologic tumor regression as the "standard." The pathologic response was quantified by tumor regression grade.


RESULTS
Positron emission tomography/computer tomography correctly identified six of eight patients (specificity 75 percent) with complete pathologic response. However, the sensitivity of positron emission tomography/computer tomography was only 45 percent and the accuracy 53 percent. The positive and negative predictive values were 83 and 33 percent, respectively.


CONCLUSIONS
We conclude that positron emission tomography/computer tomography performed seven weeks after the end of chemoradiation is not able to predict the histopathologic response in locally advanced rectal cancer. There is an obvious need for other complementary methods especially with respect to the low sensitivity of positron emission tomography/computer tomography.
Kristiansen
Charlotte
C
Danish Colorectal Cancer Group South, Vejle Hospital, Kabbeltoft 25, Vejle, Denmark. charlotte.kristiansen@vgs.regionsyddanmark.dk
Loft
Annika
A
Berthelsen
Anne K
AK
Graff
Jesper
J
Lindebjerg
Jan
J
Bisgaard
Claus
C
Jakobsen
Anders
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D003287:Contrast Media; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000517:prevention & control; D011237:Predictive Value of Tests; D011379:Prognosis; D019275:Radiopharmaceuticals; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D007472:Iohexol; C038192:iopromide