Effect of hyperthermia combined with external radiation therapy in primary non-small cell lung cancer with direct bony invasion.

PURPOSE: Local control in lung cancer directly invading the bone is extremely poor. Effects of regional hyperthermia combined with conventional external beam radiation therapy were evaluated. MATERIALS AND METHODS: Thirteen patients with non-small lung cancer (NSCLC) with direct bony invasion were treated with hyperthermia plus irradiation (hyperthermia group). The treatment outcome was compared with the historical treatment results in 13 patients treated with external radiation therapy alone (radiation alone group). In patients with no distant metastasis, radiation therapy at a total dose of 60-70 Gy was administered to both groups. Hyperthermia was performed for 45-60 min immediately after irradiation for two-four sessions with radiofrequency capacitive heating devices. RESULTS: For primary response, 10 of the 13 tumours responded to the treatment (3 CR, 7 PR) in the hyperthermia group, whereas seven tumours responded (1 CR, 6 PR) in the radiation alone group. The 2-year local recurrence-free survival rate for clinical M(0) patients in the hyperthermia group and that in the radiation alone group were 76.1 and 16.9%, respectively. Three patients died of distant metastases within 2 years in the hyperthermia group, but two out of three tumours histologically disappeared, even in the autopsy examination. The 2-year overall survival rate for clinical M(0) patients in the hyperthermia group and that in the radiation alone group were 44.4 and 15.4%, respectively. No severe pulmonary complication was observed in either group. CONCLUSIONS: Regional hyperthermia combined with conventional irradiation could be a tool to improve local control in patients with NSCLC deeply invading the chest wall.

Hyperthermia-induced apoptosis in two rat yolk sac tumor cell lines with different radiothermosensitivity in vitro.

We investigated cell susceptibility to hyperthermia-induced apoptosis in two rat yolk sac tumor cell lines (RYSTs) and attempted to correlate this with the known potentially relevant molecular determinants of apoptosis, p53 protein status, Bcl-2 family of proteins and heat shock proteins (Hsp). Parent cell line, NMT-1 (carrying wild-type p53 gene) was radiosensitive but thermoresistant compared to the variant cell line, NMT-1R (mutated type p53), which was isolated from NMT-1 by repeated radiation exposure. Induction of apoptosis by hyperthermia at 43 degrees C was morphologically detected in both RYSTs using hematoxylin and eosin, and TUNEL staining and additionally confirmed by DNA ladder formation (the cleavage of DNA into oligonucleosomal fragments). Western blot analysis showed an increase in expression of p53, p21WAF1/CIP1, Hsp70 proteins in both cell lines after heat-shock at 43 degrees C for 30 min. Hsp90 expression increased in NMT-1 but was not affected by heating in NMT-1R cells, whereas hyperthermia exerted no effect on the endogenous expression of Bax. Bcl-2 protein could not be detected in either RYST. These results suggest that hyperthermia induced apoptosis in both NMT-1 and NMT-1R and apoptosis in RYSTs may be independent of p53-dependent signaling pathway.

Clinical application of low dose-rate brachytherapy combined with simultaneous mild temperature hyperthermia.

BACKGROUND: Recent biological research has shown that mild temperature hyperthermia (MTH) around 41 degrees C simultaneously combined with low dose-rate irradiation (LDRI) is an effective treatment modality for cancer. The aim of the study was to assess the clinical usefulness of a combination of MTH and simultaneous low dose-rate brachytherapy. MATERIALS AND METHODS: Seven superficial and 8 deep-seated tumors were included in this protocol. Two tumors had no previous treatment and the remainder were recurrent tumors which had arisen from previously treated sites. The average major diameters of superficial and deep tumors were 8.6 and 7.0 cm, respectively. The average values for Tmin in superficial and deep tumors were 41.5 and 40.7 degrees C, respectively. Brachytherapy was delivered by 137Cs and/or 192Ir LDRI sources. RESULTS: For superficial tumors, six of the seven tumors responded to the treatment (4 achieved CR, 2 PR, 1 NC) and four tumors did not recur within the follow-up period of 5-15 months. All of the deep tumors responded and 5 achieved CR, 3 PR. Four tumors recurred 4-17 months after the treatment and the remainder showed no local recurrence within the follow-up period of 4-31 months. CONCLUSION: MTH simultaneously combined with LDRI was an effective method for treating progressive and bulky tumors with a previous treatment history.

Biological cell survival mapping for radiofrequency intracavitary hyperthermia combined with simultaneous high dose-rate intracavitary irradiation.

We examined the best way to combine recently developed radiofrequency intracavitary hyperthermia with simultaneous high dose-rate intracavitary brachytherapy in an original experimental model. Temperature distribution was measured with an experimental phantom which was immersed in a water bath with the temperature controlled at 37 degrees C. Radiation dose distribution was calculated with a treatment-planning computer. Cell survival was measured by colony assay with HeLa-TG cells in vitro. Radiation dose response at 1 - 7 Gy and time response with hyperthermia in the range of 40 - 46 degrees C were estimated. Radiation dose-response curves in simultaneous treatment with hyperthermia for 30 min at 37 to 46 degrees C were estimated and the surviving fractions in combined treatment were plotted against temperature. For intracavitary radiation alone, cell survival rates increased with increasing distance from the source. For intracavitary hyperthermia alone, the maximum temperature was observed at a depth of 13 mm from the surface of the applicator under suitable treatment conditions. Homogeneous cell killing from the surface of the applicator to a tumor depth of 13 mm was observed under a specific treatment condition. Our experimental model is useful for evaluating the best simultaneous combined treatment.

Interaction between low dose-rate irradiation, mild hyperthermia and low-dose caffeine in a human lung cancer cell line.

PURPOSE: To investigate cell killing by means of low dose-rate irradiation (LDRI) combined with concurrent mild hyperthermia and to determine the effect of low-dose caffeine on this combination treatment. MATERIALS AND METHODS: Human lung adenocarcinoma cells, LK87, were treated with LDRI (50 cGy/h) in combination with mild hyperthermia at 41 degrees C and low-dose caffeine (1 mM). Cell survival was estimated by clonogenic assay. Flow-cytometry was performed with PI staining using FACScan. Heat-shock protein (HSP72/73) was measured by the Western blotting method. All treatments were simultaneously performed for up to 48 h (24 Gy). RESULTS: LDRI cytotoxicities were enhanced by hyperthermia at 41 degrees C. D0 calculated from the dose-response curve for LDRI combined with 41 degrees C was 3.46 Gy whereas it was 6.55 Gy for LDRI alone. The survival curve for LDRI +41 degrees C demonstrated no chronic thermotolerance up to 48 h. For LDRI + simultaneous low-dose caffeine, cell killing was also enhanced, where D0 was 3.38 Gy at 37 degrees C. Radiosensitization caused by caffeine was enhanced by combination with simultaneous mild hyperthermia at 41 degrees C, where D0=1.78 Gy. Cell cycle analysis demonstrated remarkable G2 and mild G1 arrest for LDRI alone, but only G1 arrest was observed for LDRI combined with 41 degrees C and for LDRI combined with caffeine. Strong and early G1 arrest was observed in the treatment with LDRI + caffeine at 41 degrees C. The amount of HSP72/73 in the combination of LDRI with caffeine at 41 degrees C was less than that at 41 degrees C alone. CONCLUSION: LDRI cytotoxicity was enhanced by non-lethal hyperthermia. Low dose caffeine produced further cell killing in the combination of LDRI with mild hyperthermia.

Does AK-2123 (Senazole) have sensitizing effects on radiation, cisplatin and hyperthermia under aerobic conditions in vitro?

We investigated the sensitizing effects of AK-2123 (Senazole) on the interaction of radiation, cisplatin and hyperthermia under aerobic conditions in the rat yolk sac cell line NMT-1R in vitro. The effects were assessed by clonogenic assay. A cytotoxic effect of AK-2123 after 24 hours exposure was observed as a function of the dose. For NMT-1R cells, the ID70 of AK-2123 was 400 micrograms/ml for 24 hours exposure, which was employed for subsequent combined treatments. Although a statistically significant increase in the G1 cell fraction was observed after AK-2123 treatment with a dose of ID70 (p = 0.02) no enhancing effect of AK-2123 on radiation, cisplatin or heat response curves was detected under aerobic conditions in vitro.

Early radiation effects in highly apoptotic murine lymphoma xenografts monitored by 31P magnetic resonance spectroscopy.

PURPOSE: Phosphorus-31 magnetic resonance spectra (31P-MRS) were obtained from highly apoptotic murine lymphoma xenografts before and up to 24 hr following graded doses of radiation ranging from 2 to 30 Gy. Radiation-induced apoptosis was also estimated up to 24 hr by scoring apoptotic cells in tumor tissue. METHODS AND MATERIALS: Highly apoptotic murine lymphoma cells, EL4, were subcutaneously transplanted into C57/BL mice. At 7 days after transplantation, radiation was given to the tumor with a single dose at 3, 10, and 30 Gy. The beta-ATP/Pi, PME/Pi, and beta-ATP/PME values were calculated from the peak area of each spectrum. Radiation-induced apoptosis was scored with counting apoptotic cells on hematoxylin and eosin stained specimens (% apoptosis). RESULTS: The values of % apoptosis 4, 8, and 24 hr after radiation were 21.8, 19.6, and 4.6% at 3 Gy, 35.1, 25.6, and 14.8% at 10 Gy, 38.4, 38.0, and 30.6% at 30 Gy, respectively (cf. 4.4% in control). There was no correlation between early change in beta-ATP/Pi and % apoptosis at 4 hr after radiation when most of the apoptosis occurred. An early decrease in PME/Pi was observed at 4 hr after radiation dose at 30 Gy. For each dose, the values of beta-ATP/Pi 24 hr after radiation were inversely related to radiation dose. CONCLUSION: The increase in beta-ATP/Pi observed by 31P-MRS was linked to the degree of histological recovery from radiation-induced apoptosis.

Cytotoxic enhancement of low dose-rate irradiation in human lung cancer cells by mild hyperthermia.

PURPOSE: The aim of this study was to investigate the cell killing induced by low dose-rate irradiation (LDRI) simultaneously combined with long duration mild hyperthermia in LK87 human lung cancer cells. Cell cycle alteration due to this combined treatment was also observed. MATERIALS AND METHODS: Human lung adenocarcinoma cells, LK87, were treated with concurrent LDRI (50 cGy/hr) and mild hyperthermia (38 to 42 degrees C). Cell survival was estimated by clonogenic assay. Flow cytometry was performed with FACScan. The treatments were simultaneously performed for up to 48 hr (24 Gy). RESULTS: Survival curves of mild hyperthermia alone revealed development of chronic thermotolerance up to 48 hr, whereas LDRI plus hyperthermia caused an exponential decrease in survival. The LDRI cytotoxicities were enhanced by mild hyperthermia over a non-lethal temperature range. The Do values calculated from dose response curves at 37, 38, 39, 40, 41 41.5 and 42 degrees C were 6.55, 5.25, 4.24, 3.99, 3.46, 1.83 and 0.70 Gy, respectively. Cell cycle analysis demonstrated a remarkable G2 and a mild G1 block for LDRI alone, but only a G1 block was observed for LDRI combined with 41 degrees C hyperthermia. CONCLUSION: The LDRI cytotoxicity was enhanced by long duration mild temperature hyperthermia. The suppression of chronic thermotolerance was considered to be a mechanism involved in this sensitization.

31P NMR spectroscopy can predict the optimum interval between fractionated irradiation doses.

This study was performed to clarify whether changes in the metabolites observed by phosphorous-31 magnetic resonance spectroscopy (31P-MRS) could indicate an optimum interval between two doses of radiation in a murine tumor model. Murine mammary carcinoma cells, FM3A, were irradiated 7 days after transplantation with a single 5 Gy dose without anesthesia. 31P spectra were measured with a spectrometer up to 30 days. The beta-ATP/Pi and PCr/Pi values were calculated from the peak area of each spectrum. In a fractionation experiment, two fractions of irradiation at a 5 Gy per fraction were given at 0, 1, 2, 3 and 6 day intervals. Tumor growth delay was also scored to determine the fractionated radiation effect. In the control group, beta-ATP/Pi and PCr/Pi decreased with tumor growth. In the single irradiation group, the tumor did not grow up to day 6, and an initial rise and subsequent decrease in beta-ATP/Pi and PCr/Pi were observed. Maximum beta-ATP/Pi and PCr/Pi were observed on day 2 after irradiation. In a fractionation experiment, the greatest growth delay was observed in the two day interval group, in which maximum beta-ATP/Pi and PCr/Pi were demonstrated in 31P-MRS. Our results suggested that changes in the metabolites observed by 31P-MRS could be useful indicators for determining the fractionation schedule in radiation therapy.

Thermal enhancement of pirarubicin (THP-adriamycin) by mild hyperthermia in vitro.

It has been demonstrated that hyperthermia can enhance the cytotoxicity of several anticancer drugs. Pirarubicin (THP-adriamycin) is a less cardiotoxic derivative of adriamycin. The thermal enhancement of cytotoxicity of pirarubicin was studied at various elevated temperatures in vitro by using a Chinese hamster cell line, V79. Cell survival curves were obtained at elevated temperatures for V79 cells treated with heat given alone or in combination with pirarubicin, and D0, the treatment time to reduce cell survival from S to S/e, was obtained for each cell survival curve. The relationship between the logarithm of the D0 and the treatment temperature for cells treated with heat alone was biphasic with a breaking point at 43 degrees C, although that for cells treated with a combination of heat and pirarubicin was exponential with no breaking point. The slope of this relationship for heat alone > 43 degrees C was -0.72 +/- 0.094 h/degree C which was not significantly different from the slope for combined heat and pirarubicin, -0.64 +/- 0.032 h/degree C. The results indicated that the cytotoxicity of pirarubicin was thermally enhanced specifically by mild hyperthermia. Pirarubicin uptake into the V79 cells during hyperthermia was independent of the treatment temperature (37, 42, and 44 degrees C), suggesting that the thermal enhancement of pirarubicin was not due to the increased drug-uptake at elevated temperatures. Based on these results, it is predictable that hyperthermia combined with pirarubicin is more effective below 43 degrees C which is easily achievable clinically.

Modifications of tumor-associated antigen expression on human lung cancer cells by hyperthermia and cytokine.

The effect of hyperthermia and cytokine (IFN-gamma) in the expression of carcinoembryonic antigen (CEA) on the surface of cells was studied in vitro. The human lung cancer cell line, GLL-1, was used. The results demonstrate increase in CEA expression after hyperthermia. The magnitude of elevated CEA expression increased with increasing temperature (41-43 degrees C). Time-course study demonstrated that the peak CEA expression was 3 days after heating at 43 degrees C. The relative CEA expression was 1.3 at 1 day, 1.6 at 2 days, 1.9 at 3 days, 1.8 at 4 days, and 1.5 at 5 days, respectively. Hyperthermia plus IFN-gamma showed a synergistic effect in the expression of CEA. The four fold marked increase of CEA expression was detected. Furthermore, the pattern of time-course of CEA expression in hyperthermia combined with IFN-gamma was different from that in hyperthermia alone.