[Correlation of growth hormone receptor expression to preoperative radiosensitivity of rectal cancer patients].

Background & Objective: Growth hormone (GH) could activate pathways involved in DNA repair process by binding to growth hormone receptor (GHR), which is thought as one of the mechanisms of radioprotection. This study was to evaluate the correlation of GHR expression to radiosensitivity of rectal cancer.

Methods: The expression of GHR in biopsy specimens from 98 rectal cancer patients before preoperative irradiation and postoperative specimens was detected by immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR). Radiosensitivity was evaluated according to Rectal Cancer Regression Grading.

Results: IHC revealed that GHR overexpression was positively correlated to poor response to radiotherapy (P<0.001, rs=0.399); RT-PCR also showed that radiosensitivity was significantly higher in GHR mRNA-negative group than in GHR mRNA-positive group (P<0.001, rs=0.398). Compared with the biopsy specimens before preoperative irradiation, the paired postoperative specimens showed significantly increased GHR expression in residual cancer cells (P<0.001).

Conclusion: Detection of GHR expression before preoperative irradiation may predict radiosensitivity of rectal cancer.