Anti-tumor effects of hyperthermia plus granulocyte colony-stimulating factor.

The role of neutrophils in the anti-tumor effects of hyperthermia was investigated in an experimental rat model, and the efficacy of hyperthermia combined with recombinant human granulocyte colony-stimulating factor (G-CSF) was similarly investigated. AH109A carcinoma cells were transplanted into the hind legs of Donryu rats, then heated by a radio-frequency dielectric heater. In this study, because the myeloperoxidase (MPO) activity of neutrophils was not affected by heating or G-CSF, MPO activity was measured as an index of neutrophil migration into tumor tissue. After hyperthermia, MPO activity in tumor tissue increased significantly, suggesting migration of neutrophils into tumor tissue. Depletion of circulating neutrophils by the intraperitoneal injection of anti-rat neutrophil antibody decreased the anti-tumor effects of hyperthermia. Subsequently, we used hyperthermia plus intraarterial G-CSF to enhance the anti-tumor effect. Hyperthermia was induced 1 h after injection of G-CSF, a time when MPO activity in tumor tissue was maximal. A satisfactory thermal effect was noted even in cases where tissue could not be heated sufficiently. In conclusion, neutrophils have an important role in the anti-tumor effects of hyperthermia, and administration of G-CSF enhances these effects.

The role of active oxygen species and lipid peroxidation in the antitumor effect of hyperthermia.

The role of active oxygen species and lipid peroxidation in the antitumor effect of hyperthermia was studied in an experimental rabbit model. VX2 tumors were transplanted into rabbit hind legs, and the effect of hyperthermia on tumor growth was measured at 7 and 14 days after heating. As an index of lipid peroxidation, thiobarbituric acid-reactive substances in the tumor tissue were measured prior to hyperthermia and 3, 6, 12, and 24 h after hyperthermia. Tumor growth in rabbits treated with hyperthermia was significantly reduced, and thiobarbituric acid-reactive substances in the tumor tissue treated with hyperthermia were significantly increased until 6 h after hyperthermia. In addition, alpha-tocopherol in the tumor tissue was significantly decreased after hyperthermia. The antitumor effect of hyperthermia and the increase of thiobarbituric acid-reactive substances in the tumor tissue treated with hyperthermia were significantly inhibited by the administration of superoxide dismutase and catalase or dimethyl sulfoxide. These results suggest that lipid peroxidation mediated by active oxygen species plays an important role in the antitumor effect of hyperthermia.

[Role of polymorphonuclear leukocytes (PMN) and active oxygen species in hyperthermia--antitumor effect of hyperthermia combined with rhG-CSF].

We have reported that polymorphonuclear leukocytes (PMN) and active oxygen species from PMN may play an important role in the mechanism of the antitumor effect of hyperthermia. At this time, we focused our experimental studies on rat AH109A carcinoma treated with hyperthermia combined with arterial injection of rhG-CSF. Rats with transplantable AH109A carcinoma at the hind leg received hyperthermia. These tumors showed mild suppression of further development only by hyperthermia. However, when arterial injection of rhG-CSF was applied together with hyperthermia, marked suppression of tumor development was observed. Our data suggest that hyperthermia combined with rhG-CSF is closely related to the generation of free radical-mediated tumor cell killing, and it can be an effective treatment for cancer.

[Role of polymorphonuclear leukocytes (PMN) and active oxygen species in hyperthermia--enhancing effect of G-CSF on superoxide generation from PMN].

We examined in vitro the effect of G-CSF and temperature on superoxide (O2-) generation by Cypridina luciferin analog (CLA) dependent chemiluminescence. PMN significantly generated O2- at the concentration of G-CSF 25 ng/ml or more at 37 degrees C within the range of 0.1 from 1,000 ng/ml. O2- generation from PMN was remarkably enhanced, stimulated by opsonized zymosan (OZ) and phorbol myristate acetate (PMA), at 41 degrees C as compared with 37 degrees C. O2- generation was enhanced with the addition of 25 ng/ml of G-CSF at 41 degrees C as compared to without it at 41 degrees C. A significant enhancement of O2- generation from PMN was observed at 25 ng/ml G-CSF and 41 degrees C.

[Clinical results of hyperthermia alone in the treatment of refractory human tumors].

Retrospective analysis of patients with refractory tumors which were treated with hyperthermia alone in five institutions was performed. Hyperthermia was applied to 30 refractory tumors including 19 deep-seated tumors for a total of 427 sessions by 8 MHz or 13.56 MHz radiofrequency capacitive heating devices. Of the 30 tumors treated, 3 (10%) showed complete regression and 2 (7%) more than 50% regression. Although tumor regression was observed in small tumors, large deep-seated tumors did not respond to heat alone. Thus, response rate of hyperthermia alone was lower than expected, although subjective improvement by hyperthermia was noted in 53% patients. We consider that hyperthermia should be combined with radiation or chemotherapy whenever possible.

[Chemo-embolization using degradable starch microspheres and regional hyperthermia in unresectable hepatocellular carcinoma].

Antitumor effects and prognosis of the patients with unresectable hepatocellular carcinoma were investigated in the treatment of chemo-embolization using degradable starch microspheres (DSM) and regional hyperthermia. Twenty-six cases were treated with chemo-embolization using DSM alone (Group A) and eighteen cases were treated with combination of chemo-embolization and hyperthermia (Group B). Tumor regression rates over 50% were 42% (11/26) and 56% (10/18) in Group A and Group B, respectively. In the patients with tumors over 7 cm in diameter, no favorable response was obtained in Group A (0/11), but the response rate was increased to 56% (5/9) by the combination of hyperthermia. In the patients with arterio-portal shunt, therapeutic effects were observed in 17% (1/6) and 50% (1/2) of Group A and Group B, respectively. In the patients with portal invasion (Vp2 and Vp3), no favorable response was demonstrated in Group A (0/4), but tumor response was demonstrated in one out of 3 cases in Group B. One- and two-year survival rates were 59% and 53%, respectively, in Group A, and 93% and 45%, respectively, in Group B. The DSM, temporary embolus, is suitable for the combination of hyperthermia because chemo-embolization using DSM can be performed many times. Therefore, these results suggested that chemo-embolization using DSM should be beneficial as combination therapy for unresectable hepatocellular carcinoma.

[Antitumor effect and indication of chemoembolization using degradable starch microspheres and regional hyperthermia in patients with hepatocellular carcinoma].

Antitumor effects and indications of chemoembolization using degradable starch microspheres (DSM) and regional hyperthermia were investigated in patients with unresectable hepatocellular carcinoma. Chemoembolization using DSM was performed in 40 cases and fourteen cases were treated with the combination of hyperthermia. Tumor regression rate over 50% was 48% (chemoembolization alone: 42%, combined hyperthermia: 57%). Though one and two year survival rates were 62% and 54% respectively in the treatment with chemoembolization alone, one year survival rate was 91% in the treatment with combined hyperthermia. From the viewpoint of antitumor effect, it was thought that effectual indications of chemoembolization using DSM alone were the cases whose tumor size were below 7 cm and portal invasion were negative. These indications however were spread by the combination of hyperthermia. The DSM, temporary embolus, is suitable for combination of hyperthermia because chemoembolization using DSM can be performed many times. The cases with clinical stage III and obstruction of the first branch of portal veins did not become severe hepatic failure because DSM was temporary embolus. Therefore, from the viewpoint of safety, chemoembolization using DSM has almost the same indications as intra-arterial infusion therapy. These results suggested that chemoembolization using DSM will be a beneficial methods as combination therapy for unresectable hepatocellular carcinoma.

[Role of lipid peroxidation and polymorphonuclear leukocytes-derived oxygen radicals in acute gastric lesions induced by hyperthermic treatment].

Acute gastric lesions were experimentally induced by local hyperthermic treatment (42 degrees C, 40 min). Thiobarbituric acid (TBA) reactants in the gastric mucosa were significantly increased 40 min after the hyperthermia. There were no changes in gastric mucosal blood flow and gastric acid secretion. The total area of gastric erosions and TBA reactant in gastric mucosa of rats deficient in vitamin E were significantly increased compared with those of rats supplemented with vitamin E. The increase in the total area of gastric erosions and TBA reactants in gastric mucosa were significantly inhibited by the treatment of bovine Cu, Zn-SOD and bovine catalase, and by the depletion of polymorphonuclear leukocytes (PMN). Allopurinol did not show any influence on these pathological changes induced by hyperthermia. These results suggest that lipid peroxidation and PMN-derived oxygen radicals may play an important role in the pathogenesis of gastric lesions induced by hyperthermic treatment.

[Chemoembolization and regional hyperthermia with degradable starch microspheres in the treatment of malignant hepatic tumors].

Antitumor effects of chemoembolization with degradable starch microspheres (DSM) combined with regional hyperthermia (HT) were investigated in patients with hepatocellular carcinoma and metastatic liver cancer. Chemoembolization with DSM was performed in 39 cases of hepatocellular carcinoma (HCC) and in 25 cases of metastatic liver cancer. Thirteen cases of HCC and 3 cases of metastatic liver cancer were treated with the combination of HT. A catheter was placed in the proper hepatic artery via the trans-femoral approach. Adriamycin or Mitomycin C mixed with DSM was injected every 2 or 3 weeks through the catheter. Thermotron RF-8, the heating device used in this study, is operated at 8 MHz radiofrequency. Hyperthermia treatment was applied twice a week. The therapeutic effect of this treatment was evaluated by the change in tumor size measured by angiography or computed tomography. Tumor regression over 50% was observed in 42% of the patients with HCC treated with chemoembolization alone and in 54% of those with chemoembolization and HT. In the patients with metastatic liver cancer, tumor regression over 50% was observed in 65% of the patients treated with chemoembolization alone and in 33% of those with chemoembolization and HT. One-year survival rate after the initial treatment in patients with HCC was 66% and 89% in the patients treated with chemoembolization alone and with chemoembolization and HT, respectively. One and two-year survival rates in the patients with metastatic liver cancer was 55% and 41% in the treatment with chemoembolization alone. These results suggest that chemoembolization using DSM was markedly effective in the patients with malignant hepatic tumors, particularly in metastatic liver cancer.

[Effects of hyperthermia combined with chemoembolization using degradable starch microspheres in the treatment of hepatocellular carcinoma].

Twenty-eight cases with non-resectable hepatocellular carcinoma were examined. Chemoembolization using degradable starch microspheres (DSM) was performed in 19 cases. DSM, 40-45 micron in diameter, which are degraded by serum amylase, temporarily obstruct arterial blood flow at capillary bed. Adriamycin mixed with DSM was injected into patients through the proper hepatic artery. Hyperthermia (8 MHz radiofrequency) combined with chemoembolization was performed in 9 cases. In all cases treated by hyperthermia combined with chemoembolization, the intratumoral temperature was measured by a thermocouple thermometer during heating alone and heating after injection of DSM. The therapeutic effect was evaluated by the change in tumor size measured by angiography or computed tomography. The efficacy of hyperthermia combined with chemoembolization was compared with that of chemoembolization alone. Intratumoral temperature was 1.0 degree C higher by heating after injection of DSM than by heating alone. Partial response (tumor regression of over 50%) was observed in 8 of 19 cases (42%) with chemoembolization alone. Partial response was observed in 6 of 9 cases (67%) with hyperthermia combined with chemoembolization. One-year survival rate was 58% in chemoembolization alone, against 83% in hyperthermia combined with chemoembolization. Our results suggest that hyperthermia combined with chemoembolization using DSM is effective in the treatment of hepatocellular carcinoma.