Department of General Surgery, O.O. Bohomolets National Medical University. Kiev. Ukraine.
Address for correspondence: Y Susak, Department of General Surgery, O.O. Bohomolets National Medical University, Holosiivsky prosp. 59a, 03039 Kyiv, Ukraine.

Summary: Ukrain (NSC 631570) is a drug with direct antineoplastic and immunomodulating activity. Ukrain has previously been observed to stimulate fibrotic changes in malignant tissues and to lead to tumor encapsulation of breast cancer. The present study was performed to define histological features of pancreatic ductal adeno­carcinoma following Ukrain administration. Six nonsmoking male patients aged 57 ± 5 years and with histo­logically verified ductal adenocarcinoma localized in the body of the pancreas underwent surgery for duodenal obstruction. All patients had previously received palliative surgical treatment followed by chemotherapy with gemcitabine or 5-fluorouracil. Due to extremely severe adverse events, chemotherapy was discontinued. All patients then received one to three courses of Ukrain (30 mg weekly, 120 mg per course), the last injection of Ukrain being administered 10-12 h before surgery for duodenal obstruction. Necrotic area squares were found to have increased by 50%-70% compared with stains taken prior to Ukrain administration. Perivascular sclero­sis was also present; this is not common in spontaneous processes in the pancreas. Necrosis especially pre­sented at sites where parenchymal elements predominated over stromal ones. Microcirculation disorders were present in the form of perivascular and perineural hemorrhages, tissue infiltration with blood, connective tissue disaggregation, erythrocyte aggregation and adhesion, and pathological changes to vascular walls. Signs of fib­rinoid infiltration and of the percolation of malignant tissues with fibrin are common morphological features in the development of pancreatic cancer under Ukrain therapy, and this leads to the encapsulation of cancer cells and prevention of metastasis. The formation of collagen following fibrinoid infiltration may separate individual malignant cells or small groups of malignant cells, leading to dystrophic changes, such as the blocking of mucus secretion. The other important feature was tissue prosoplasia: an increase of differentiation grade in pre­viously less differentiated malignant cells was observed. This occurred predominantly in tumors rich in vascu­larization and parenchymal elements.