STRAP is a strong predictive marker of adjuvant chemotherapy benefit in colorectal cancer.
BACKGROUND
Molecular predictors for the effectiveness of adjuvant chemotherapy in colorectal cancer are of considerable clinical interest. To this aim, we analyzed the serine threonine receptor-associated protein (STRAP), an inhibitor of TGF-beta signaling, with regard to prognosis and prediction of adjuvant 5-FU chemotherapy benefit.


METHODS
The gene copy status of STRAP was determined using quantitative real-time polymerase chain reaction in 166 colorectal tumor biopsies, which had been collected from a randomized multicenter trial of 5-fluorouracil (5-FU)/mitomycin C (MMC) adjuvant chemotherapy of the Swiss Group for Clinical Cancer Research (SAKK).


RESULTS
Amplification of STRAP was found in 22.8% of the tumors. When left without adjuvant chemotherapy, patients bearing tumors with a STRAP amplification had a significantly better prognosis (hazard ratio for death: 0.26; P=.004). Interestingly, these patients, when receiving adjuvant treatment, had a worse survival (hazard ratio for death: 3.48; P=.019) than without chemotherapy, whereas patients carrying tumors with diploidy or deletion of STRAP benefited from the treatment (hazard ratio for death: 0.44; P=.052). This suggests the amplification of STRAP as a strong predictor of an unfavorable effect of 5-FU-based adjuvant chemotherapy.


CONCLUSIONS
If confirmed, the STRAP gene copy status might provide a parameter to decide about the use of 5-FU-based adjuvant chemotherapy.
Buess
Martin
M
Department of Oncology, University Hospital of Basel, Basel CH-4031, Switzerland.
Terracciano
Luigi
L
Reuter
Jurgen
J
Ballabeni
Pierluigi
P
Boulay
Jean-Louis
JL
Laffer
Urban
U
Metzger
Urs
U
Herrmann
Richard
R
Rochlitz
Christoph
C
D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000032:analysis*; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D017024:Chemotherapy, Adjuvant; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000401:mortality; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D018628:Gene Dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D016685:Mitomycin / Q000627:therapeutic use; D016133:Polymerase Chain Reaction; D011379:Prognosis
D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; C434146:Strap protein; D016685:Mitomycin; D005472:Fluorouracil
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