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Thymidylate synthetase mRNA levels are increased in liver metastases of colorectal cancer patients resistant to fluoropyrimidine-based chemotherapy

Massimo Libra15, Patrick M Navolanic25, Renato Talamini3, Erica Cecchin1, Franca Sartor1, Salvatore Tumolo4, Sara Masier1, Salvatore Travali5, Mauro Boiocchi6 and Giuseppe Toffoli1*

  • * Corresponding author: Giuseppe Toffoli

  • † Equal contributors

Author Affiliations

1 Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico, Istituto Nazionale Tumori, IRCCS, Aviano (PN), Italy

2 Department of Microbiology & Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA

3 Unit of Epidemiology and Biostatistic, Centro di Riferimento Oncologico, Istituto Nazionale Tumori, IRCCS, Aviano (PN), Italy

4 Oncolgy Unit, Azienda Ospedaliera Santa Maria degli Angeli, Pordenone, Italy

5 Department of Biomedical Sciences, University of Catania, Italy

6 Division of Experimental Oncology 1, Centro di Riferimento Oncologico, Istituto Nazionale Tumori, IRCCS, Aviano (PN), Italy

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BMC Cancer 2004, 4:11  doi:10.1186/1471-2407-4-11

Published: 25 March 2004



Fluoropyrimidines such as 5-fluorouracil (5-FU) and 5-fluoro-2'deoxyuridine (FUDR) are among the most effective chemotherapeutic agents for treatment of metastatic colorectal cancer (CRC). Increased expression of thymidylate synthetase (TS) in CRC metastases has been proposed to be an important mechanism of resistance to fluoropyrimidine-based chemotherapy.


The present study investigated whether TS mRNA levels in liver metastases of 20 CRC patients before treatment with FUDR by hepatic arterial infusion (HAI) correlated with frequency of clinical response or survival duration.


Median survival duration of patients with TS mRNA levels above and below the median was 15 and 18 months, respectively (p > 0.05). Clinical response was achieved in 40% of patients with low TS mRNA levels, but in only 20% of patients with high TS mRNA levels (p = 0.01). TS mRNA levels were also measured for liver metastases of 7 of the patients that did not achieve a clinical response. A statistically significant increase in expression of TS mRNA was observed for liver metastases resistant to chemotherapy (21 ± 14) in comparison to liver metastases of the same patients before chemotherapy (8 ± 4) (p = 0.03).


This is the first report to demonstrate increased TS expression in liver metastases from CRC patients resistant to fluoropyrimidine based chemotherapy. These findings are consistent with previous studies indicating that increased TS expression is associated with resistance to fluoropyrimidine-based chemotherapy.

Thymidylate Synthetase; Liver Metastasis; Colon Rectal Cancer; FUDR