Radioimmunoguided Surgery In Gastric Cancer: Using GDP Developed By-self And Assessment Of Occult Mmetastases

Objectivc Firstly, to estabIish the approach of radioimmunogUided surgeryfOr gastric cancer using a new GDP(hand-held gamma detecting probe) developed by-self Secondly, to assess its reliability and characteristic of the GDP The last, to studyoccult metastases found by the mGS system and evaluate its sensitivity,specificity andaccuracy. Methods To develop a new GDP by-self and to test its performance. Usingthe new inventory, thirty patients with gastric cancer were undetwentradiodrimunogUided surgery. Radioimmuno-detecting by the new GDP andradioimmunoimaging by SPECT were perfOrmed in vitro continuously befOre surgery.For accuate radioirmunoscint igraphy of carcinomatous lesions, oo"Tc was used toreveal gastric mucosa. AlI tissue samples removed by the surgeon were diagnosed byhistology and immunohistochemistry of CEA to check the accuracy of RID results.Lymph node samples were diagnosed by reverse transcriptase-polymerase chainreaction of Cytokeratinl9 additionaIly Results (1) GDP conformed to the enterprosestandard of products. The main parametes of the GDP revealed that background countrate was 62 CPM, sensibitity 5476CPM/MBq, spatial resolution 9.53 rnm and the thaestability was l.2%/8h. (2) The RIGS aPProach for gastric cancer was established.Themean thoe suit fOr operating was 6.6I 1.6 days after administration,while lesions werevisualized clearly 24h later after administration. In seveal patients, anormal rare factionor defect of radioactivity of WeTc were found in lesions. By intraoperative detecting, thecounts of target sites were obtained, and tumor-to-normal tissue (TM) ratios werecalculated. The TM ratio of 3.2; 1 was taken as the lowest threshold value of positivegastric wall iallltration, and 2.7:1 for lymph node metastasis. (3) By detecting with theganuna-detecting probe in vitro before surgery, it was predicted that metastases existedin pelvic peritoneum in 3 patients and in hilum of spleen in 2 patients. (4) All tumorwere correctly localized intraoperatively. For the detection of lymphatic metastasis, thesensitivity of RIGS was 90.7%, the specificity 98.0%, and the accuracy 94.6%. Of thosehistologically negative lymph nodes, the existences of occult metastasis were fOund byRID in l7.9% (22/123), CEA IHC 7.3% (9/123) and CKl9 RT-PCR l9.5%(24/l23)resPectively. Based on the RIGS system, 26.7% (8 of 30) of patients were upstagedfrom stage IHl to stage IINV RadioirnInunogUided surgery changed the surgicalprocedure in 5 cases. (5) No toxicity related to radionuclide or monoclonal antibodieswas observed in any patients or doctors. Conclusion This study validates the use ofGDP (HTZ type) for the intraoperative detection of carcinomatous lesions in gastriccanceL RlGS is more specific,efficient and reliable than traditional exploration inidentifying occult metastases. As a complementary teclinique to traditional radicalgastrectomy, RIGS is particularly helpfUl for operating individually and reasonably andwill Anprove patients' prognosis and survival quality hereby. (3) Both CEA IHC andCK19 RT-PCR can benefit identifying occult metastases that is not available for moreconventional methods.