Hyperthermia in the treatment of cancer. Perspectives on its promise and its problems

Low-dose hyperthermia enhances the antitumor effects of chemotherapy in squamous cell carcinoma

Esophageal squamous cell carcinoma is a highly aggressive neoplasm and the sixth leading cause of global cancer-related death; the 5-year survival rate for esophageal cancer is only about 20%-25% for all stages. Therefore, improving the therapeutic effect is important. This study assessed whether low-dose hyperthermia (LDH) enhances the antitumor effects of chemotherapy. The antitumor effect of chemotherapy with/without LDH in the squamous cell carcinoma cell line SCCVII was evaluated. A comprehensive analysis was performed with real-time polymerase chain reaction (PCR) to study the hyperthermia-induced changes in the gene expression of SCCVII cell lines. In addition, the cytotoxic and apoptotic changes in the cells treated with LDH combined with/without 5-fluorouracil (5-FU) were measured. LDH combined with 5-FU (10 nM) strongly inhibited the cell growth of SCCVII, with flow cytometry showing an increased population of apoptotic cells. PCR showed that LDH promoted a 25.22-fold increase of p53 mRNA and 18.08-fold increase of Bax mRNA in vitro. MDR1 expression was decreased to 28.7% after LDH. This treatment can result in much higher efficacy of antitumor drugs. After LDH, the expressions of TS decreased to 12.06%, OPRT increased by 4.17-fold, and DPD did not change (1.03-fold). This transformations will induce susceptibility to 5-FU. LDH may be a useful enhancer of chemotherapy drugs for squamous cell carcinoma.

Nanoparticle-mediated hyperthermia in cancer therapy

A small rise in tumor temperature (hyperthermia) makes cancer cells more susceptible to radiation and chemotherapy. The means of achieving this is not trivial, and traditional methods have certain drawbacks. Loading tumors with systematically asministered energy-transducing nanoparticles can circumvent several of the obstacles to achieve tumor hyperthermia. However, nanoparticles also face unique challenges prior to clinical implementation. This article summarizes the state-of-the-art current technology and discusses the advantages and challenges of the three major nanoparticle formulations in focus: gold nanoshells and nanorods, superparamagnetic iron oxide particles and carbon nanotubes.

Local cerebral hyperthermia induces spontaneous thrombosis and arteriolar constriction in the pia mater of the mouse

The effect of local cerebral hyperthermia on responses of pial microvessels of the mouse was investigated. A set protocol was followed, involving the performance of a craniotomy on anaesthetized animals and using intravital microscope-television closed circuitry. Controlled hyperthermic exposure was applied regionally by heating the brain surface with irrigating artificial cerebrospinal fluid. Microvascular responses such as changes in diameter, thrombosis and embolism were monitored and video-taped observations were further viewed and analysed. When both brain surface and core body temperatures were kept at 37 degrees C, no changes in pial microvessels were noted. With core body temperature kept at 37 degrees C and at a brain surface temperature of 43.1 degrees C, passing emboli and arteriolar constriction were observed. A few minutes later, visible thrombosis was prevalent. Further spontaneous thrombo-embolic activity continued and at the end of a 50-min hyperthermic exposure, arterioles attained a constriction of 37%. Thrombus formation was sometimes massive enough to occlude fully the microvessel. The protocol followed in this study can be adopted to other small animal species and for a variety of experimental procedures involving hyperthermia and the pial microcirculation.

Lethal interaction between heat and methylene blue in Escherichia coli

Hyperthermia treatment is shown to act synergistically with methylene blue (MB), from the end point of lethality in Gram-negative Escherichia coli bacteria. That this lethality is correlated to the damage produced in DNA by the dye is deduced from the fact that bacteria differing in capacity for repair are almost equally sensitive to heat, but differ considerably in sensitivity to concomitant heat and dye treatment. It is demonstrated that the damage is repairable by the excision-repair system. The role of temperature seems to be that of facilitating the incorporation of the dye, which enables the latter to intercalate into the DNA. Ability of the outer membrane of E. coli AB1157 bacteria to act as a barrier to the penetration of MB remains almost intact up to 46 degrees C, but above this temperature it seems to disrupt abruptly (but reversibly), leading to inactivation of the cells by the dye. Since hyperthermia is in current use for the treatment of cancer, it is suggested that if this synergism also exists in mammalian cells, MB could eventually be used independently of its photodynamic action as an adjuvant in cancer therapy.

Systemic hyperthermia in the treatment of HIV-related Kaposi's sarcoma. A phase I study

Ten Caucasian males with HIV-related Kaposi's sarcoma, a disseminated disease which is refractory to usual therapies, underwent a single session of systemic hyperthermia with maintenance of core temperatures at 42 degrees C for 1 h. One complete remission and 7 partial remissions were identified when assessed 30 days post-treatment. Two mixed responses were noted in patients whose tumors showed autocrine growth. At 60 days 2 of the 7 partial responders began to show tumor progression. The complete remission persisted at 120 days. Surrogate markers of HIV activity fell in all responding patients. In no patient was there evidence of HIV activation. No adverse effects of heating were noted on CMV retinitis. Hairy leukoplakia resolved with heating in all patients. CD4 counts showed no appreciable change in any of the 8 patients with a presenting CD4 count below 60. In the 2 patients who presented with a CD4 count above 400, CD4 counts rose dramatically following treatment. No deaths were noted in this phase I study. The use of systemic hyperthermia in treatment of HIV-related illness warrants further study.

Clinical research into hyperthermia treatment of cancer using a 430 MHz microwave heating system with a lens applicator

Tokyo Metropolitan Komagome Hospital, Kyoto University Hospital, and Aichi Cancer Center used a lens applicator microwave equipment, the HTS-100, to treat 90 patients with a total of 96 tumours. The results were analysed, and the following conclusions reached. Three clinical cases have been presented to illustrate the features of the HTS-100. (1) The results of 383 heating sessions using the HTS-100 were analysed. Even tumours larger and deeper than 5 cm could be heated above 42 degrees C. The heating area is much wider than that of the other 2450, 915, 430 MHz microwave heating equipments. (2) Hyperthermia treatment using the HTS-100 was combined with radiotherapy. The percentage effectiveness in terms of CR+PRa was 66.3% for the 89 cases which could be evaluated. Even for tumours larger than 5 cm, and deeper than 4 cm, local control was achieved in 60.7%. Thus, the indications for microwave heating have been significantly expanded. (3) Combination of microwave heating and RF heating is a new protocol which also expands the indications for hyperthermia therapy. (4) The percentage of patients experiencing the side-effects of pain, a sensation of heat, and burns was 15.6%, 6.3%, and 3.6%, respectively. Most of these side-effects were mild and temporary. The percentage of patients experiencing pain was higher than in conventional microwave heating, probably because the area of heating was wider. (5) In the future, the HTS-100 can be expected to play an important role in clinical cancer hyperthermia.

Correlation between redistribution of a 26 kDa protein and development of chronic thermotolerance in various mammalian cell lines

Previous studies suggested that a 26 kDa protein might play an important role in protein synthesis-independent thermotolerance development in CHO cells. To determine if this phenomenon was universal, four mammalian cell lines, viz., CHO, HA-1, murine Swiss 3T3, and human HeLa, were studied. Cells were heated at 42 degrees C, and the level of 26 kDa protein in the nucleus was measured, together with clonogenic survival and protein synthesis. The results demonstrated that 1) the 26-kDa protein was present in the four different cell lines, and 2) the level of the 26 kDa protein in their nuclei was decreased by 30-70% after heating at 42 degrees C for 1 hr. However, restoration of this protein occurred along with development of chronic thermotolerance. The protein synthesis inhibitor cycloheximide (10 micrograms/ml) neither inhibited the development of chronic thermotolerance nor affected the restoration of the 26 kDa protein in the nucleus. In fact, this drug protected cells from hyperthermic killing and heat-induced reduction of 26 kDa protein in the nucleus. Heat sensitizers, quercetin (0.1 mM), 3,3'-dipentyloxacarbocyanine iodide (DiOC5[3]: 5 micrograms/ml), and stepdown heating (45 degrees C-10 min----42 degrees C), potentiated hyperthermic killing and inhibited or delayed the restoration of the 26 kDa protein to the nucleus. These results support a correlated, perhaps causal relationship between the restoration of the 26 kDa protein and chronic thermotolerance development in four different mammalian cell lines.

Heating characteristics of a 430 MHz microwave heating system with a lens applicator in phantoms and miniature pigs

Heating experiments on phantoms and miniature pigs were performed using two types of lens applicator and a conventional waveguide applicator fed by a 430 MHz microwave heating system (HTS-100, manufactured by Tokyo Keiki Co., Ltd). Temperature distributions in agar phantoms and miniature pigs were measured at regular intervals during heating. The following results were thus obtained: (1) The effective heating depth varied with the focal length, showing the lens effect. (2) Using a four-aperture lens applicator in miniature pigs, a heating depth of 6 cm was obtained. This almost doubles the depth of conventional waveguide applicator. The heating area was 12 X 6 cm at the depth of 4 cm. (3) Dielectric properties of the buttocks of the miniature pig were virtually identical to those of the agar phantom containing 0.35% NaCl and 0.05% NaN3.

Hyperthermia for the treatment of brain tumors

Brain malignancy, either primary or metastatic, in general is associated with a very poor outcome in spite of the best therapy modern medicine has to offer. The multimodality approach appears to offer the best chance of achieving our goal of improved survival (quality and quantity) and ultimately cure. Hyperthermia, though its application to brain cancer remains experimental, has proven itself in its ability to improve cancer therapy results. There are many methods available to apply hyperthermia to the brain and its application, thus far, has been quite safe. Continued research in this exciting field is warranted.

Laser-induced hyperthermia in the treatment of liver tumors

Seven patients with malignant liver tumors were treated with Nd:YAG laser induced hyperthermia. The laserthermia was performed during laparotomy using Nd:YAG laser with contact sapphire probes with power settings of 6 W. The contact tip was placed into the middle of the tumor and the temperature in 1.5-2.0 cm from the middle of the tumor was raised and held between 41C and 45C for ten minutes. One fatal complication appeared caused by an air embolism. In the postoperative fine needle biopsies on third and fifth postoperative day the sytologic finding in the tumor was necrosis. However, in 30% of the samples there was also a suspicion of cancer cells. In the computer tomography four weeks after the treatment there were also signs of necrosis. It seems that selective destruction of malignant liver tumors is possible with contact Nd:YAG laser induced hyperthermia.

Hyperthermia effects on the growth of a laryngeal squamous cell carcinoma cell line treated with recombinant human interferons alpha and gamma

Clinical therapy with either interferon alpha or interferon gamma is associated with a febrile response. However, the effects of hyperthermia on the response to these interferons have not been elucidated fully. In this study, a cell line derived from a laryngeal squamous cell carcinoma (JHU-011-SCC-L-P) was grown in the presence of recombinant human interferon alpha (rHuIFN alpha) or recombinant human interferon gamma (rHuIFN gamma) and incubated at either 37 degrees or 39 degrees C, and cell growth rates were measured. Cells incubated with rHuIFN alpha demonstrated no difference in growth rates from control cells. Cells treated with rHuIFN gamma showed significant inhibition of growth at both temperatures, and the ratio of decreased growth at 39 degrees C was significantly greater than for the rHuIFN alpha and control groups. This hyperthermic effect did not depend on the continued exposure to rHuIFN gamma, and the effect appeared to depend on the duration of hyperthermia instead of the time sequence of hyperthermic exposure. Moreover, initial treatment at 39 degrees C for 24 hours was ineffective in producing the hyperthermic response produced with continuous hyperthermic exposure. These findings would indicate that the effect of rHuIFN gamma on this laryngeal squamous cell carcinoma cell line is enhanced significantly at 39 degrees C compared with 37 degrees C. There appears to be no similar hyperthermia-augmented antiproliferative effect of rHuIFN alpha-treated cells.

Intractible cutaneous non-Hodgkin's lymphoma of the lower limb. Complete remission after sequential regional isolated hyperthermic perfusion and perfusion with 1-phenylalanine-mustard (melphalan, L-Pam)

A 61-year-old man with an intractible and progressively disabling cutaneous non-Hodgkin's lymphoma (NHL) in the lower limb was treated with sequential regional isolated perfusion at 10-day intervals. The first perfusion was hyperthermic (40.2-43.1 degrees C tumor-temperature); the second was at controlled normothermia with high-dose 1-phenylalanine mustard (melphalan, L-Pam; 11 mg/l perfused tissue). This treatment resulted in a complete remission in the perfused area of significant duration and has prevented amputation.

Low dose reirradiation in combination with hyperthermia: a palliative treatment for patients with breast cancer recurring in previously irradiated areas

Ninety-seven patients with breast cancer recurring in a previously irradiated area (mean dose 44 Gy) were reirradiated in combination with hyperthermia and had evaluable tumor responses. In the reirradiation series, radiotherapy was given twice weekly in most patients, with a fraction size varying from 200 to 400 cGy, the total dose varying from 8 to 32 Gy. Hyperthermia was given following the radiotherapy fractions. The combined treatment resulted in 35% complete and 55% partial responses. Duration of response was median 4 months for partial response and 26 months for complete response, respectively. The median survival time for all patients was 12 months. Acute skin reaction was mild, with more than moderate erythema in only 14/97 patients. Thermal burns occurred in 44/97 patients, generally at sites where pain sensation was decreased, and therefore they did not cause much inconvenience. In the 19 patients who survived more than 2 years, no late radiation damage was observed. When patients who received a "high dose" (greater than 29 Gy and hyperthermia) were compared with those who received a "low dose" (less than 29 Gy and hyperthermia), a higher complete response rate was observed in the high dose group (58% vs. 24%), whereas no difference in acute toxicity was found. We conclude that reirradiation with 8 x 4 Gy in combination with hyperthermia twice weekly is a safe, effective and well tolerated method for palliative treatment of patients with breast cancer recurring in previously irradiated areas.

Response of canine oral carcinomas to heat and radiation

Thermal enhancement of radiation response improved the probability for local tumor control without increasing the risk for late complications in this study of relatively advanced stage tumors. Thirty-eight dogs with naturally occurring oral carcinomas were randomized to two radiation dose response groups to receive radiation alone or combined with local hyperthermia. Radiation was delivered in 10 fractions over 22 days. Heating was done 3 hours after seven of the radiation doses. The objective was to maintain a minimum tumor temperature of 42 degrees C and a maximum normal tissue temperature of 40 degrees C for 30 minutes. Normal tissue temperatures were usually 40 degrees C or less but there was great heterogeneity in tumor temperatures. Temperatures at tumor margins never exceeded 41.5 degrees C. The TCD50 for radiation was 38 Gy (32-46 Gy, 95% C.I.) and for radiation and heat it was 33 Gy (30-36 Gy, 95% C.I.). The slope of the dose response was much steeper for radiation and heat than for radiation alone indicating that the heterogeneity of tumor response was decreased with heat. All tumors were controlled at 40 and 45 Gy with heat whereas only 57% and 75% were controlled with 40 and 45 Gy radiation only. There were no late necroses for radiation and heat. The tumor control enhancement might be improved with different sequences, number of heatings or other time temperature relationships. It is not possible to predict the optimum treatment scheme because of the lack of knowledge of the influence of hyperthermia on subsequent heat or radiation treatments. That influence could be affected greatly by changes in tumor microcirculation, pH, and oxygenation as well as development and decay of thermotolerance in tumor and normal tissue.

Retrospective analysis of the response of tumours in patients treated with a combination of radiotherapy and hyperthermia

One hundred and twelve patients with various carcinomas were treated on 112 fields with radiotherapy and hyperthermia, using non-invasive techniques. Radiotherapy dose ranged from 13-70 Gy (except for one patient receiving hyperthermia alone) with a mean of 28.6 Gy. The combined treatment was primarily aimed at giving palliation; 79 per cent of the patients had received previous irradiation on the same area. Hyperthermia was given twice weekly following radiotherapy. From the temperature data collected, 12 different parameters expressing the hyperthermia 'dose' were derived. The various parameters for both treatment modalities, i.e. radiotherapy and hyperthermia, and some of the tumour parameters were statistically evaluated with respect to their influence on tumour response. The overall response rate was 87 per cent including 33 per cent complete response. The complete response rate increased with increasing radiotherapy total dose, i.e. from 23 per cent (14-25 Gy) and 38 per cent (28-36 Gy) to 60 per cent (greater than 38 Gy). A positive correlation between the tumour temperature parameter representative of the coldest spot in the tumour, and the level of response was found. Achievement of complete response appeared also to be determined to a considerable extent by radiotherapy total dose as well as tumour volume. The correlation between response level and the minimum hyperthermia dose parameters persisted, however, after correction for the influence of tumour volume and radiotherapy total dose. These results support the opinion that higher tumour response rates can be achieved by increasing the hyperthermia treatment level at the coldest spot in the tumour.

Thermoradiotherapy for persistent cancer in previously irradiated fields

Among some 300 patients undergoing clinical trails with localized radiofrequency hyperthermia, 42 whose cancers had persisted or recurred after conventional radiotherapy were selected for additional limited radiation plus hyperthermia. There were 10 complete responses to therapy, 13 partial responses and one patient was considered nonevaluable. In the remaining 18 patients there was minor regression, stabilization or progression of the tumor. After completion of treatment, five of the tumors appeared operable and surgical resection was accomplished in four. The results of this study support the concept that hyperthermia has a potentiating effect when used in conjunction with radiation therapy.

Intracranial temperature during passive heat exposure in humans

Intracranial and skin temperature, evaporative response and rating of thermal comfort/discomfort were monitored during passive therapeutic hyperthermia. Intracranial temperature at the end of normal therapeutic sessions was significantly lower when face-fanning had been performed. Although face-fanned subjects remained in the sweating box twice as long as patients, their intracranial temperature was not statistically different from that of patients. Thermal injury to the human brain during passive therapeutic hyperthermia may therefore be efficaciously retarded by face-fanning.

Hyperthermia for cancer: a practical perspective

A causal relationship between hyperpyrexia and tumor regression was first suggested in 1866, when Busch reported the cure of a histologically diagnosed sarcoma in a middle-aged woman, following a bout of erysipelas. Over the years, interest in the effect of heat on cancer has remained alive, but this interest has increased dramatically in recent years. The literature on this subject is broadly reviewed and the clinical results discussed. It is apparent from clinical studies thus far that it is a relatively simple undertaking to treat superficial neoplasms with hyperthermia. However, the major challenges in clinical thermotherapy pertain to patients with deeply situated tumors. The lack of safe and reliable methods of monitoring temperature in deep tissues is a major impediment to a thorough understanding of thermal dosimetry in clinical hyperthermia, and routine thermal dosimetry in clinical hyperthermia will have to await the development of reliable noninvasive thermometry. As responses have been reported with modest levels of hyperthermia, the need for thermometry is somewhat lessened, given that invasive monitoring is imperfect and somewhat risky when used in deeply seated tumours. The eventual place of thermotherapy in the treatment of malignant tumours in man is as yet unclear and must be rigourously and thoroughly assessed in well-designed, prospective, randomized patient trials.