Abstract: Objective To evaluate the feasibility of using ¹³¹I-EGF to assess tumor response to chemotherapy. Methods BALB/c-Anu mice were inoculated with A549 lung adenocarcinoma cells，and randomly divided into four groups when tumor diameters reached 0.8~1.2cm：the control group was treated with 0.1ml of saline；the taxol group，with 5mg/kg of taxol；the cisplatin group，with 4mg/kg of cisplatin；and the combined chemotherapy group，with 5mg/kg of taxol and 4mg/kg of cisplatin.Scintigraphic studies were conducted at 0，7，14，21 and 28 d after the treatments.The ratio of radioactivity of tumor to non-tumor tissue（T/NT）was calculated using the region of interest（ROI）technique.After the last imaging，the mice were sacrificed. The ratios of radioactivity in tumor/blood and tumor/muscle were also measured.Tumor volume was determined and used to calculate tumor growth inhibition rates in each group.Dynamic images were acquired every 0.5min for the first 30min，using a SPECT system.The biodistribution of ¹³¹I-EGF was determined at the end of the imaging session. Results Tumors could be clearly visualized on the ¹³¹I-EGF images. The distribution of ¹³¹I-EGF showed that chemotherapeutic groups had lower tumor/muscle radioactivity ratio（taxol，9.829；cisplatin，12.636；combined，12.313） and tumor/blood ratios（taxol，3.384；cisplatin，2.826；combined，2.713） than the control group（all P<0.05）．Similarly，T/NT ratios in the three chemotherapy groups were significantly lower than in the control group（F=1011.251，P<0.01）.Differences between the control group and each treatment group were consistent with the relative tumor volumes in each group. Conclusions There may be a correlation between ¹³¹I-EGF uptake and therapeutic efficacy after chemotherapy in tumor tissue，suggesting that ¹³¹I-EGF may be useful for evalu-ating tumor response to treatment． 

Key words:  Lung neoplasms, ¹³¹I-EGF, Mice, Nude, Drug therapy, Radionuclide imaging