Etoposide sensitizes CT26 colorectal adenocarcinoma to radiation therapy in BALB/c mice.
OBJECTIVE
To investigate the combined effect of etoposide and radiation on CT26 colorectal adenocarcinoma implanted into BALB/c mice.


METHODS
We evaluated the radiosensitizing effect of etoposide on CT26 colorectal adenocarcinoma in a syngeneic animal model. BALB/c mice were subcutaneously implanted with CT26 cells and divided into four groups: control (intra-peritoneal salineX2) group, etoposide (5 mg/kg intra-peritoneallyX2) group, radiation therapy (RT 5 GyX2 fractions) group, and combination therapy with etoposide (5 mg/kg intra-peritoneally 1 h before radiation) group.


RESULTS
Tumor growth was significantly inhibited by RT and combination therapy. The effect of combination therapy was better than that of RT. No significant changes were noted in body weight, plasma alanine aminotransferase, or creatinine in any group. The leukocyte count significantly but transiently decreased in the RT and combination therapy groups, but not in the etoposide and control groups. There was no skin change or hair loss in the RT and combination therapy groups.


CONCLUSIONS
Etoposide can sensitize CT26 colorectal adenocarcinoma in BALB/c mice to RT without significant toxicity.
Liu
Chia-Yuan
CY
Department of Radiation Oncology, Mackay Memorial Hospital, No. 92 Section 2 Chung San North Road, Taipei 104, Taiwan, China.
Liao
Hui-Fen
HF
Wang
Tsang-En
TE
Lin
Shee-Chan
SC
Shih
Shou-Chuan
SC
Chang
Wen-Hsuing
WH
Yang
Yuh-Cheng
YC
Lin
Ching-Chung
CC
Chen
Yu-Jen
YJ
D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D005047:Etoposide / Q000627:therapeutic use*; D051379:Mice; D008807:Mice, Inbred BALB C; D011878:Radiotherapy / Q000379:methods*
D000972:Antineoplastic Agents, Phytogenic; D005047:Etoposide