Early prediction of response to first-line chemotherapy by sequential [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography in patients with advanced colorectal cancer.
BACKGROUND
To evaluate [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET), for early evaluation of response to palliative chemotherapy and for prediction of long-term outcome, in patients with metastatic colorectal cancer (mCRC).


METHODS
In a randomized trial, patients with mCRC received irinotecan-based combination chemotherapy. FDG-PET was carried out before treatment and after two cycles in 51 patients at two centers. Visual changes in tumor FDG uptake and changes measured semi-automatically, as standard uptake values (SUVs), were compared with radiological response after four and eight cycles.


RESULTS
The mean baseline SUV for all tumor lesions per patient was higher in nonresponders than in responders (mean 7.4 versus 5.6, P = 0.02). There was a strong correlation between metabolic response (changes in SUV) and objective response (r = 0.57, P = 0.00001), with a sensitivity of 77% and a specificity of 76%. There was no significant correlation between metabolic response and time to progression (P = 0.5) or overall survival (P = 0.1).


CONCLUSIONS
Although metabolic response assessed by FDG-PET reflects radiological tumor volume changes, the sensitivity and specificity are too low to support the routine use of PET in mCRC. Furthermore, PET failed to reflect long-term outcome and can, thus, not be used as surrogate end point for hard endpoint benefit.
Byström
P
P
Department of Oncology and Pathology, Karolinska Institute, Stockholm, Sweden.
Berglund
A
A
Garske
U
U
Jacobsson
H
H
Sundin
A
A
Nygren
P
P
Frödin
J-E
JE
Glimelius
B
B
D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002166:Camptothecin / Q000031:analogs & derivatives; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000556:secondary; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D000077146:Irinotecan; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D019275:Radiopharmaceuticals
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000077146:Irinotecan; D002166:Camptothecin