Molecular markers and prediction of response to chemoradiation in rectal cancer

M. Sambasiva Rao*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Preoperative chemotherapy and radiation (chemoradiation) are increasingly used in the treatment of advanced rectal carcinoma to downstage the tumor so that a sphincter sparing procedure is used. This treatment modality has also resulted in not only local disease control but also decreased metastasis and increased survival. It is well known that with standard chemoradiation some tumors show marked pathologic response, while others remain non-responsive. Identification of tumor markers that can predict responsiveness to chemoradiation is extremely useful to avoid unnecessary preoperative treatment. To understand the role of thymidylate synthase (TS), p53 and Bcl-2 proteins, if any, in tumor response/resistance to chemoradiation, we examined pretreatment biopsy material obtained from 12 responsive and 13 non-responsive patients by immunohistochemistry. TS was undetectable in 11 of 12 (92%) responsive tumors and overexpressed in only 1 tumor (8%); whereas, p53 or Bcl-2 was overexpressed in 8 tumors (66%). In the nonresponsive group of 13 tumors, overexpression of TS, p53 and Bcl-2 was observed in 7, 5 and 6 tumors, respectively. In 6 non-responsive tumors in which TS was undetectable, 5 tumors contained high levels of p53 or Bcl-2. These results indicate that level of TS in tumors is the best predictor of sensitivity or resistance to chemoradiation. No such correlation between overexpression of p53 and Bcl-2 and response to chemoradiation is observed.

Original languageEnglish (US)
Pages (from-to)497-500
Number of pages4
JournalOncology reports
Issue number3
StatePublished - 2001


  • Bcl-2
  • Chemoradiation
  • P53
  • Rectal cancer
  • Thymidylate synthasc

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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