Local tumor hyperthermia in combination with radiation therapy. 1. Malignant cutaneous lesions

Thermo-haemodynamic coupling during regional thigh heating: Insight into the importance of local thermosensitive mechanisms in blood circulation

A positive relationship between local tissue temperature and perfusion exists, with isolated limb-segment hyperthermia stimulating hyperaemia in the heated region without affecting the adjacent, non-heated limb segment. However, whether partial-limb segment heating evokes a heightened tissue perfusion in the heated region without directly or reflexly affecting the non-heated tissues of the same limb segment remains unknown. This study investigated, in 11 healthy young adults, the lower limb temperature and haemodynamic responses to three levels of 1 h upper-leg heating, none of which alter core temperature: (1) whole-thigh (WTH; water-perfused garment), (2) quadriceps (QH; water-perfused garment) and (3) partial-quadriceps (PQH; pulsed shortwave diathermy) heating. It was hypothesised that perfusion would only increase in the heated regions. WTH, QH and PQH increased local heated tissue temperature by 2.9 ± 0.6, 2.0 ± 0.7 and 2.9 ± 1.3°C (P < 0.0001), respectively, whilst remaining unchanged in the non-heated hamstrings and quadriceps tissues during QH and PQH. WTH induced a two-fold increase in common femoral artery blood flow (P < 0.0001) whereas QH and PQH evoked a similar ∼1.4-fold elevation (P ≤ 0.0018). During QH and PQH, however, tissue oxygen saturation and laser-Doppler skin blood flow in the adjacent non-heated hamstrings or quadriceps tissues remained stable (P > 0.5000). These findings in healthy young humans demonstrate a tight thermo-haemodynamic coupling during regional thigh heating, providing further evidence of the importance of local heat-activated mechanisms on the control of blood circulation.

Quo Vadis Oncological Hyperthermia (2020)?

Heating as a medical intervention in cancer treatment is an ancient approach, but effective deep heating techniques are lacking in modern practice. The use of electromagnetic interactions has enabled the development of more reliable local-regional hyperthermia (LRHT) techniques whole-body hyperthermia (WBH) techniques. Contrary to the relatively simple physical-physiological concepts behind hyperthermia, its development was not steady, and it has gone through periods of failures and renewals with mixed views on the benefits of heating seen in the medical community over the decades. In this review we study in detail the various techniques currently available and describe challenges and trends of oncological hyperthermia from a new perspective. Our aim is to describe what we believe to be a new and effective approach to oncologic hyperthermia, and a change in the paradigm of dosing. Physiological limits restrict the application of WBH which has moved toward the mild temperature range, targeting immune support. LRHT does not have a temperature limit in the tumor (which can be burned out in extreme conditions) but a trend has started toward milder temperatures with immune-oriented goals, developing toward immune modulation, and especially toward tumor-specific immune reactions by which LRHT seeks to target the malignancy systemically. The emerging research of bystander and abscopal effects, in both laboratory investigations and clinical applications, has been intensified. Our present review summarizes the methods and results, and discusses the trends of hyperthermia in oncology.

A computational study of cancer hyperthermia based on vascular magnetic nanoconstructs

The application of hyperthermia to cancer treatment is studied using a novel model arising from the fundamental principles of flow, mass and heat transport in biological tissues. The model is defined at the scale of the tumour microenvironment and an advanced computational scheme called the embedded multiscale method is adopted to solve the governing equations. More precisely, this approach involves modelling capillaries as one-dimensional channels carrying flow, and special mathematical operators are used to model their interaction with the surrounding tissue. The proposed computational scheme is used to analyse hyperthermic treatment of cancer based on systemically injected vascular magnetic nanoconstructs carrying super-paramagnetic iron oxide nanoparticles. An alternating magnetic field is used to excite the nanoconstructs and generate localized heat within the tissue. The proposed model is particularly adequate for this application, since it has a unique capability of incorporating microvasculature configurations based on physiological data combined with coupled capillary flow, interstitial filtration and heat transfer. A virtual tumour model is initialized and the spatio-temporal distribution of nanoconstructs in the vascular network is analysed. In particular, for a reference iron oxide concentration, temperature maps of several different hypothesized treatments are generated in the virtual tumour model. The observations of the current study might in future guide the design of more efficient treatments for cancer hyperthermia.

GROWTH OF MALIGNANT CELLS AND THERMODYNAMICS

In the present paper, certain thermodynamic relations are considered to study tumor growth and how the mechanisms, responsible for the cell killing by temperature change in abnormal cells, can be estimated from direct measurements, during evolution of a tumor. The problem is considered in its most general form and the discussion focuses on how significant results can be estimated from: (i) The stress system acting on the tumor, tumor pressure and tumor volume changes measured by ultra-sonic computerized tomography, (ii) entropy change and entropy production, measured from the heat capacity profiles, and (iii) the chemical potential changes measured by fluorescent labeling techniques; all of them supported by other techniques based on histo-chemical and microscopic methods.

Modelling mass and heat transfer in nano-based cancer hyperthermia

We derive a sophisticated mathematical model for coupled heat and mass transport in the tumour microenvironment and we apply it to study nanoparticle delivery and hyperthermic treatment of cancer. The model has the unique ability of combining the following features: (i) realistic vasculature; (ii) coupled capillary and interstitial flow; (iii) coupled capillary and interstitial mass transfer applied to nanoparticles; and (iv) coupled capillary and interstitial heat transfer, which are the fundamental mechanisms governing nano-based hyperthermic treatment. This is an improvement with respect to previous modelling approaches, where the effect of blood perfusion on heat transfer is modelled in a spatially averaged form. We analyse the time evolution and the spatial distribution of particles and temperature in a tumour mass treated with superparamagnetic nanoparticles excited by an alternating magnetic field. By means of numerical experiments, we synthesize scaling laws that illustrate how nano-based hyperthermia depends on tumour size and vascularity. In particular, we identify two distinct mechanisms that regulate the distribution of particle and temperature, which are characterized by perfusion and diffusion, respectively.

The tolerance of reirradiation and hyperthermia in breast cancer patients with reconstructions

BACKGROUND

Breast cancer recurrences in previously irradiated areas are treated with reirradiation (reRT) and hyperthermia (HT). The aim of this retrospective study is to quantify the toxicity of HT in breast cancer patients with reconstruction.

METHODS

Between 1992 and 2009, 36 patients were treated with reRT with a scheme of 8 fractions of 4.0 Gy in 4 weeks, and HT on a total of 37 tissue reconstructions. The types of reconstructions were: split-thickness skin graft (15), transverse rectus abdominis myocutaneous flap (1), latissimus dorsi flap (14), rhomboid flap (1) or a combination of grafts and flaps (6). Toxicities were graded according to the Common Terminology Criteria for Adverse Events (CTCAE), version 3.0. Patient, tumour, and treatment characteristics predictive for the endpoints were identified in univariate and multivariate analyses. The primary endpoint was HT toxicity. Secondary endpoints were acute and late radiotherapy (RT) toxicity, complete response (CR), local control (LC) and overall survival (OS).

RESULTS

The median follow-up time was 64 months. Grade 2 HT toxicity occurred in four patients and grade 3 in three. The three patients with grade 3 HT toxicity required reoperation. None of the evaluated parameters showed a significant relationship with HT toxicity. The CR rate in 15 patients with macroscopic disease was 80%. The 3 and 5 year LC rates were 74% and 69%; the median OS was 55 months.

CONCLUSIONS

Combined reRT and HT in breast cancer patients with reconstruction is safe and effective.

Targeted magnetic hyperthermia

Many nanotechnologies, which enable unique approaches to treat cancer, have been developed based upon non-toxic organic and inorganic materials to improve current cancer treatments. The use of inorganic materials to form magnetic nanoparticles for hyperthermia therapy is of great interest for localized treatment of cancers without effecting adjacent healthy tissue. Extensive clinical trials have begun using magnetic hyperthermia in animal models. The purpose of this article is to address different factors that affect targeting, heating and biodistribution to safely control the therapeutic efficacy of targeted magnetic hyperthermia. This method involves accumulation of magnetic nanoparticles at a tumor site and then manipulating the magnetic properties of the nanoparticles to heat the targeted tissues.

Thermotherapy in dermatologic infections

The use of local induced hyperthermia or thermotherapy for dermatologic infections has not been fully explored in the more recent medical literature. Herein, we discuss the rationale behind the use of thermotherapy and review reported clinical experience with its use in the management of cutaneous infections.

Heating the patient: a promising approach?

There is a clear rationale for using hyperthermia in cancer treatment. Treatment at temperatures between 40 and 44 degrees C is cytotoxic for cells in an environment with a low pO(2) and low pH, conditions that are found specifically within tumour tissue, due to insufficient blood perfusion. Under such conditions radiotherapy is less effective, and systemically applied cytotoxic agents will reach such areas in lower concentrations than in well perfused areas. Therefore, the addition of hyperthermia to radiotherapy or chemotherapy will result in at least an additive effect. Furthermore, the effects of both radiotherapy and many drugs are enhanced at an increased temperature. Hyperthermia can be applied by several methods: local hyperthermia by external or internal energy sources, regional hyperthermia by perfusion of organs or limbs, or by irrigation of body cavities, and whole body hyperthermia. The use of hyperthermia alone has resulted in complete overall response rates of 13%. The clinical value of hyperthermia in addition to other treatment modalities has been shown in randomised trials. Significant improvement in clinical outcome has been demonstrated for tumours of the head and neck, breast, brain, bladder, cervix, rectum, lung, oesophagus, vulva and vagina, and also for melanoma. Additional hyperthermia resulted in remarkably higher (complete) response rates, accompanied by improved local tumour control rates, better palliative effects and/or better overall survival rates. Generally, when combined with radiotherapy, no increase in radiation toxicity could be demonstrated. Whether toxicity from chemotherapy is enhanced depends on sequence of the two modalities, and on which tissues are heated. Toxicity from hyperthermia cannot always be avoided, but is usually of limited clinical relevance. Recent developments include improvements in heating techniques and thermometry, development of hyperthermia treatment planning models, studies on heat shock proteins and an effect on anti-cancer immune responses, drug targeting to tumours, bone marrow purging, combination with drugs targeting tumour vasculature, and the role of hyperthermia in gene therapy. The clinical results achieved to date have confirmed the expectations raised by results from experimental studies. These findings justify using hyperthermia as part of standard treatment in tumour sites for which its efficacy has been proven and, furthermore, to initiate new studies with other tumours. Hyperthermia is certainly a promising approach and deserves more attention than it has received until now.

Transpupillary thermotherapy of occult subfoveal choroidal neovascularization in patients with age-related macular degeneration

OBJECTIVE

To evaluate the efficacy of transpupillary thermotherapy for the treatment of occult subfoveal choroidal neovascularization (CNV) in patients with age-related macular degeneration.

DESIGN

A retrospective, noncomparative case series.

PARTICIPANTS

Sixteen eyes of 15 consecutive patients who presented with occult subfoveal choroidal neovascularization secondary to age-related macular degeneration.

INTERVENTION

After informed consent was obtained, 16 eyes of 15 patients were treated with transpupillary thermotherapy. All patients underwent pretreatment fluorescein angiography and were deemed untreatable by the Macular Photocoagulation Study standard. Transpupillary thermotherapy was delivered using a diode laser at 810 nm. A variable spot size of 1.2 mm, 2.0 mm, or 3.0 mm was used depending on the size of CNV. The diode laser was delivered through a contact lens, and treatment was initiated in one spot for 60 seconds' duration at a power range between 360 and 1000 mW. The end point was an area of no visible color change to a light-gray appearance.

MAIN OUTCOME MEASURES

In all eyes, outcome was assessed by Snellen chart visual acuity and clinical examination. In 10 of 16 eyes, preoperative and postoperative fluorescein angiography and optical coherence tomography were available. In the remaining 6 of 16 eyes, exudation was measured by postoperative clinical examination alone.

RESULTS

Three eyes (19%) showed a two-or-more-line improvement in visual acuity over a period of 6 to 25 months. Mean follow-up was 13 months. Visual acuity remained stable (no change or one-line improvement) in nine treated eyes (56%). The remaining four eyes (25%) showed a decline (equal to one-line worsening or greater) in visual acuity. Fifteen eyes (94%) demonstrated decreased exudation on fluorescein angiography, optical coherence tomography, and/or clinical examination.

CONCLUSIONS

Transpupillary thermotherapy shows no deleterious side effects in treating occult subfoveal choroidal neovascularization. A randomized, prospective study is necessary to evaluate treatment efficacy.

Transpupillary thermotherapy

Hyperthermia has long been recognized as potentially useful in the treatment of human neoplasms. Only recently has technology allowed hyperthermic treatment to be delivered to ocular structures in the form of ultrasound, microwave, or ferromagnetic energy. A novel technique, transpupillary thermotherapy, allows the direct application of hyperthermic energy to posterior segment ocular structures. The treatment of two posterior segment diseases, choroidal melanoma and choroidal neovascularization attributable to age related macular degeneration, are reviewed in this article.

Successful treatment of cutaneous Kaposi's sarcoma by the 585-nm pulsed dye laser

The clinical appearance of Kaposi's sarcoma (KS) can cause significant disfigurement and lead to functional impairment, particularly if the lesions ulcerate and become secondarily infected. We describe a patient with a KS plaque on the face that was successfully treated with 585-nm pulsed dye laser (PDL) therapy. No recurrence of the tumor was noted 12 months after the final laser treatment.

Effect of whole-body hyperthermia on AIDS patients with Kaposi's sarcoma: a pilot study

The safety and possible efficacy of extracorporeal whole-body hyperthermia (WBHT) were evaluated in the first FDA-approved feasibility study of WBHT in persons with AIDS. Six gay men, aged 20-50 years, CDC class C-3, underwent 1 h of WBHT at either 40 degrees C or 42 degrees C, employing a system that minimizes the physiological and biochemical changes that occur during WBHT. All subjects had Kaposi's sarcoma (KS), were free of opportunistic infections, and had significant elevations of plasma HIV RNA. During the treatment, there were no adverse side effects and all subjects tolerated WBHT without problems. KS lesions partially regressed immediately following WBHT in all subjects but returned to pretreatment status in five of six patients at 1 week. In subjects treated at 40 degrees C, CD4 counts decreased during the 8-week follow-up period; they remained unchanged, however, following 42 degrees C WBHT. Viral load remained unchanged following WBHT in subjects treated at 40 degrees C. Treatment at 42 degrees C resulted in an immediate reduction in HIV RNA that was not sustained at 1 week post-WBHT. We conclude that WBHT is safe in subjects with advanced HIV disease and that it may have a role in treating HIV infection. A larger controlled trial involving two treatments in less immunocompromised subjects is currently in progress to test this hypothesis.

New therapeutic strategies in the treatment of murine diseases induced by virus and solid tumors: biology and implications for the potential treatment of human leukemia, AIDS, and solid tumors

Understanding the biology and treatment of various cancers (including leukemia) and immunodeficiency disorders is still an ongoing and experimental process. Animal models have been and continue to be important to this process. This review will focus in on work by ourselves and others that have used murine models assessing the effects in vivo of the Friend virus complex (FVC, composed of a spleen focus forming virus and a murine leukemia helper virus) and solid tumors with metastatic potential in order to evaluate new and innovative therapies. These therapies include radiation, hyperthermia, and newly recognized naturally occurring biomolecules termed cytokines. These cytokines include, but are not limited to, the interferons, the tumor necrosis factors, the interleukins, the hematopoietic colony stimulating factors, lactoferrin and E-type prostaglandins. For example, it has been found that lactoferrin, when administered early enough, prolongs the survival of mice injected, but not yet infected, with the FVC. Of even greater potential usefulness is that mice already infected with the FVC can be completely rescued from death by treatment with split low dosage (150 cGy) total body irradiation. Irradiation treatment was associated with restoration of the T helper to T suppressor cell ratio, natural killer cell activity and marrow proliferative responses to the mitogens PHA and con A which were compromised by the FVC. More recent studies in our laboratory have demonstrated the potential of the interleukins and colony stimulating factors to decrease the metastatic potential of the B16 melanoma and the Lewis Lung Carcinoma cell lines. The cytokines can act in greater than additive fashion and combinations of therapies are possible. This review is meant to increase the awareness of these investigative animal models and the new types of combination therapies that can then be used as the basis for future clinical trials evaluating therapeutic efficacy.

Lung metastases after curative or noncurative irradiation of microscopic primary melanomas

Melanomas growing in the feet of syngeneic C57BL/6 mice were treated with a single dose of X-irradiation. After doses of 0, 3.75, 7.5, 10, 20, or 30 Gy the tumor-bearing limb was amputated at tumor sizes 1, 2, 3, 4, or 5 mm. After doses of 40, 50, 62.5, or 72.5 Gy, progressive tumor growth did not occur, and amputation of tumor-bearing limbs was done when controls were 1, 2, 3, 4, or 5 mm in size. Eighteen days after amputation the mice were killed, and pulmonary metastases were documented at autopsy. None of the mice developed pulmonary metastases after curative irradiation of the primary foot tumor. After subcurative irradiation there was a significant increase (P less than .003) in pulmonary metastases. The size of the primary melanoma is important in the prediction of these metastases. In this model melanomas can be cured by an adequate dose of irradiation, but in those not cured the incidence of lung metastases is increased. The impact of this biologic phenomenon on survival is unclear.

The current and potential role of hyperthermia in radiotherapy

Current clinical experience strongly suggests that hyperthermia will become an important modality as an adjuvant to radiotherapy in the treatment of locally advanced solid tumors. Hyperthermia must therefore be considered a topic of general interest. Biologically, hyperthermia has two different types of interactions with radiation. Firstly, heat has a radiosensitizing effect. This is most prominent with simultaneous application, but is of the same magnitude in both tumor and normal tissue and will not improve the therapeutic ratio unless the tumor is heated to a higher temperature than the normal tissue. Secondly, hyperthermia exhibits a direct cytotoxic effect, and a moderate heat treatment alone can almost selectively destroy tumor cells in a nutritionally deprived chronically hypoxic and acidic environment. Because such cells are the most radioresistant, a smaller radiation dose is needed to control the remaining more radiosensitive cells. If critical, irradiated normal tissues are also heated, the cytotoxicity is best utilised if heat is given at least 3-4 hours after irradiation. The magnitude of both the sensitizing and the cytotoxic effect depends on temperature and heating time. Clinically, heating of superficial tumors (e.g. breast, neck nodes and malignant melanoma) has confirmed the biological rationale for using hyperthermia as an adjuvant to radiotherapy. An overview of available data gives thermal enhancement ratios of approximately 1.5 in several superficial tumor sites after external heating. From a practical point of view, true simultaneous treatment is almost impossible using external heating, and the major effect of the combined treatment will have to rely on hyperthermic cytotoxicity. This makes the design of clinical schedules less complicated since only a few heat fractions may be needed to achieve an optimal effect. On this basis, several randomized clinical trials have been activated with the aim to evaluate the role of adjuvant hyperthermia in the primary treatment of advanced (superficial) tumors. In addition, studies are underway to specifically elucidate the clinical relevance of thermotolerance and other biological issues. So far, the clinical evaluation has almost solely been limited to superficial tumors, or to situations where interstitial heating is feasible. External heating of "deep" seated tumors is still preliminary, and most studies are in Phase I-II, with emphasis on toxicity and feasibility. The initial results are promising with regard to improved tumor control and acceptable toxicity.

An investigation into the combined effects of X-irradiation and 3MHz ultrasound-induced hyperthermia on pig skin

The thermal enhancement of radiation-induced damage in pig skin has been investigated. Heating at 43 degrees C for 60 min was produced by a scanned 3MHz ultrasound transducer, immediately after single doses of X rays. The ED50 values for the dermal reactions of dusky/mauve erythema and necrosis after irradiation alone were 18.6 +/- 0.5 Gy and 20.5 +/- 0.4 Gy, respectively. The reduction in the ED50 values to 15.3 +/- 0.4 Gy and 17.7 +/- 0.5 Gy after irradiation plus heating was significant and suggested a thermal enhancement ratio (TER) of between 1.15 and 1.22. These TER values were within the range obtained in both pig and rat skin using other 'dry' heating methods. This would suggest that the non-thermal effects of ultrasound do not influence the thermal enhancement of x-irradiation damage.

Whole-body hyperthermia decreases lung metastases in lung tumor-bearing mice, possibly via a mechanism involving natural killer cells

The effects of whole-body hyperthermia (WBH) on the course of the Lewis lung carcinoma (LLC) and B16 melanoma (B16) were examined. WBH was generated by microwave (2450 MHz) at an intraperitoneal temperature of 39.5-40.0 degrees C and an intratumoral temperature of 40.0-40.5 degrees C for 30 min once a week, X 3 (LLC) or X 6 (B16). The mice were sacrificed 21 days (LLC) or 42 days (B16) after tumor implantation and lung metastases were scored. Natural killer (NK)-cell activity was determined against the YAC-1 tumor target in WBH-treated tumor-bearing mice as well as in tumor-bearing mice but untreated controls. The number of lung metastases was significantly reduced and NK-cell activity was higher in animals treated with WBH. Thus, this study suggests that WBH interferes with the spread of organ metastases, possibly through a mechanism involving NK cells.

The differential response of the skin in young and old rats to a combination of X-rays and 'wet' or 'dry' hyperthermia

The left hind feet of groups of female rats aged 7, 14 and 52 weeks were irradiated at three dose levels of X-rays (20, 25 or 30 Gy). Hyperthermia (42.5 degrees C for 1 h) was carried out immediately following irradiation using either 'wet' or 'dry' heat, achieved by immersion in either water or fluorocarbon liquid. The results demonstrated that 'wet' heat produced a consistently greater enhancement of the irradiation damage than 'dry' heat. The thermal enhancement ratio for irradiation plus 'wet' heat was approximately 1.5 and for irradiation plus 'dry' heat it was in the range 1.17 to 1.39. Immersion of the feet in fluorocarbon liquid at 37 degrees C did not significantly modify the irradiation response of the skin. The lower thermal enhancement ratios obtained using immersion in fluorocarbon liquid at 42.5 degrees C are close to those obtained in large animal studies and also similar to the limited amount of data from clinical studies where microwave or ultrasound heating techniques were used. It has been demonstrated that there are large age-related differences in the response of the rat foot skin to irradiation alone. It has also been shown in the present study, using rats of the same age, that the response to irradiation plus hyperthermia was less age dependent. This finding may reflect the differing methods by which damage occurs in tissue after irradiation or hyperthermia.

Hyperthermochemoradiotherapy and esophageal carcinoma

Cancer of the esophagus still poses considerable treatment problems, with a poor 5-year survival rate after surgery, an even worse outlook after radiation and surgery, and a not very satisfactory response to chemotherapy. After several years of continued research, in 1983 we developed a Radio Frequency System with endotract electrode and thermosensors for administering hyperthermochemoradiotherapy to patients with carcinoma of the esophagus. Results in 129 patients are discussed. Immediate improvement of subjective complaints and decrease or elimination of the cancer lesion are so distinct that this treatment, by means of an endotract antenna, shows promise as a modality for esophageal lesions and may find application in diseases such as colorectal cancer or carcinoma of the uterine cervix.

Phase I trial of thermochemotherapy for brain malignancy

High-grade primary and refractory brain tumors and metastases to the brain from other primary sites are associated with a grave prognosis. Treatment, usually palliative, consists of some combination of surgery, radiation, and chemotherapy. Recently, noninvasive hyperthermia by magnetic-loop induction has been safely used to treat patients with advanced cancer in extracranial sites. Both disease regression and disease stabilization have been observed. This technique was recently applied to brain tumors in an animal model, and its safety was again demonstrated. As a result, a Phase I trial of noninvasive localized hyperthermia in combination with intravenous chemotherapy has been carried out in ten patients whose primary or metastatic brain tumors failed to respond to standard therapy. Ten patients underwent 23 thermochemotherapy sessions using the magnetic-loop induction device. The median, maximum temperature of normal brain after 1 hour of hyperthermia was 41.1 degrees C (range, 38.6 degrees C-43.4 degrees C); the median, maximum temperature of brain tumor was 42.5 degrees C (range, 38.8 degrees C-46.3 degrees C) (P less than 0.01). The temperatures of both the normal brain and brain tumor were obtained during 18 treatments. The tumor temperature was greater than the normal brain temperature in 15 of 18 treatments. In 78% of the treatments, the measured tumor temperature reached at least 42 degrees C, whereas the normal brain reached 42 degrees C in only 13% of the treatments. These data demonstrate the "selective inability" of brain tumor tissue to dissipate heat. Vital signs, intracranial pressure, and neurologic status were monitored throughout the hyperthermia treatments. No mortality or increase in chemotherapeutic toxicity could be attributed to the thermochemotherapy. In addition, there were no local complications or permanent neurologic complications. Two patients with elevated intracranial pressure before therapy had transient neurologic deficits that may have been exacerbated by the hyperthermia. It is concluded that this new, noninvasive modality not only produced effective intracranial tumor heating, but could be performed safely with the proper precautions. Phase II trials are warranted.

Improved response of a murine fibrosarcoma (Meth-A) to interstitial radiation when combined with hyperthermia

Removable Iridium-192 implants provided a dose of 10 Gy/day or 41.5 cGy/hr at 0.5 cm from the center of 1.0 cm diameter tumors. The total radiation (x) alone was 20, 40 or 60 Gy, representing 2, 4, or 6 days of continuous radiation. The doses used for the combined treatments at elevated temperatures were 10, 20 or 30 Gy. The local tumor hyperthermia (LTH) treatment (43.6 for 35 min, water bath) was administered once for each 10 Gy of dose. The combined radiation + LTH was clearly superior to that achieved with radiation or LTH alone and yielded Thermal Enhancement Ratios (TER) of 3.4-3.9. Local tumor control rate was 67% and 89% for the 20 and 30 Gy x + LTH groups, respectively. A comparison of the results obtained in this study with those of earlier studies on the same tumor system indicate that the effects of Iridium-192 alone on this rapidly proliferating tumor were comparable to similar total doses of fractionated external beam radiation. Iridium + LTH produced a tumor response comparable to that achieved with external fractionated radiation + LTH. Combined treatment effect of elevated temperature appears to be less dose rate dependent in the range of 40 cGy/hr to 100 cGy/min and more dependent upon total dose accumulation.

Local hyperthermia in combination with definitive radiotherapy: increased tumor clearance, reduced recurrence rate in extended follow-up

Fifty-nine patients with superficial malignancies appropriate for treatment with definitive radiotherapy and technically suitable for application of local microwave hyperthermia were available for at least 6 months follow-up. Thirty-one of these patients presented with two lesions, only one of which was heated, the other serving as internal control. The responses of the lesions which were heated were compared with those receiving only radiation. The heated lesions responded more quickly, reconfirming observations previously made. However, at subsequent 6 months, 1 year, 18 months and 2 years follow-ups, tumor clearance was shown to be significantly more complete as compared with the internal controls. At 6 months follow-up complete response with combined therapy was observed in 27 of 31 lesions (87%) in contrast to complete response in 12 of 31 (39%) lesions treated with radiotherapy alone. At one year combined modality treatment produced complete response in 19 of 19 lesions (100%) while radiotherapy alone yielded complete response in 10 of 19 lesions (53%). At 18 months, 8 of 9 lesions (89%) treated with combined therapy remained controlled, 1 having recurred. Seven of 9 (78%) treated by radiotherapy alone were controlled, 2 having recurred. At 2 years, 6 patients were available for follow-up and 6 of 6 (100%) of lesions treated with combined modality remained controlled. Among those treated by radiotherapy alone, 5 of 6 (83%) remained controlled, while 1 recurred. The rate of tumor recurrence among the heated lesions was significantly lower than was found among the controls. The recurrence rate among the controls was similar to that expected in a similar group of patients treated with definitive radiotherapy. Therefore, in addition to its established capability to shrink tumors, hyperthermia in combination with radiotherapy has been shown to increase the rate of overall tumor clearance and reduce recurrences compared with that obtained from radiotherapy alone.

Effect of microwave irradiation (2450 MHz) on murine cytotoxic lymphocyte and natural killer (NK) cells

Male Balb/c mice were exposed in an anechoic chamber to 2450 MHz CW microwaves at 5, 10, 15, and 20 mW/cm2, 4 hours daily for 4 days, under controlled environmental conditions. T-cell cytotoxicity and natural killer (NK) cell activity were compared in exposed and sham animals. A significant decrease (p less than 0.001) of cell-mediated cytotoxicity was observed only for a power density of 20 mW/cm2. A significant increase (p less than 0.01) in NK activity was demonstrated following exposures at 15 mW/cm2.

Combination radiofrequency hyperthermia and chemotherapy (BCNU) for brain malignancy. Animal experience and two case reports

Patients with high-grade primary and metastatic brain malignancies have a median survival time of 3-8 months, regardless of therapy. Because MagnetrodeTM hyperthermia provides safe, deep internal heating without normal-tissue injury, we studied its effects first on the brain and surrounding tissues of rabbits. The normal rabbit brain (n = 26) could be heated to potentially tumoricidal temperatures (42-43 degrees C) without apparent histopathologic or clinical damage to the brain, skull, external eye, subcutaneous tissue or skin. Intracranial pressure did not rise significantly. Using transplanted VX-2 carcinoma, we showed both the safety and potential efficacy of thermochemotherapy (IV BCNU: 14 mg/kg) in the presence of a solid brain tumor. The average maximum brain temperature achieved was 43.06 degrees C. Mean survival from the time of tumor implantation in the treated group (n = 16) was 18.56 days, compared to 9.3 days for untreated controls (n = 30) (p less than .0001). Two patients have been treated with localized brain hyperthermia combined with intravenous BCNU (80 mg/m2) for a total of eight treatments. Maximum normal brain temperature achieved was 40.0 degrees C in Patient #1 and 41.5 degrees C in Patient #2. A tumor temperature of 42.9 degrees C was achieved in Patient #2. Intracranial pressure remained within the upper limits of normal. Swan-Ganz monitoring in Patient #1 revealed a stable cardiac index and mean pulmonary artery pressure with mild fluctuations in the CVP, PAD, and PCW. No increase in chemotherapy toxicity was observed and no normal tissue injury occurred in either patient. We conclude that non-invasive localized radiofrequency hyperthermia to the brain is feasible and can be performed safely in the presence of a solid brain tumor.

Uniform regional heating of the lower trunk: numerical evaluation of tumor temperature distributions

The temperature distributions in deep seated tumors resulting from uniform heating of the abdominal and pelvic regions of the trunk are predicted from a one dimensional numerical solution of the bio-heat transfer equation. The effect of tumor size and location are investigated for two tumor perfusion models: uniform perfusion and a concentric annulus perfusion model. Tumor temperature distributions are considered acceptable if the range of temperatures in the tumor lie between 42 degrees C and 60 degrees C. This range of tumor temperatures is defined as Tave +/- 2 sigma where sigma is the population standard deviation of tumor temperatures from the average computed at the nodal points in the finite difference array. To simulate practical clinical restrictions, muscle and fat temperatures are not allowed to exceed 44 degrees C, significant portions of the viscera are not allowed to exceed 42 degrees C, and the total absorbed power required to maintain steady state cannot exceed two kilowatts. Over 100 possible cases are presented in a compact form. From this study it appears that heating systems with power deposition patterns approximately uniform are promising for heating deep-seated tumors. Small, detectable tumors (approximately 2 cm in size) are adequately heated for a wider range of conditions than are larger tumors. Excessively high temperatures in deep-seated, normal tissue could be a significant limitation for this technique.

Tumor control and therapeutic gain with different schedules of combined radiotherapy and local external hyperthermia in human cancer

Tumor control and therapeutic gain have been evaluated in a series of studies on patients with multiple lesions employing different protocols of combined radiotherapy (RT) and local external hyperthermia (HT). Tumor response has been evaluated during a follow-up ranging 6 to 18 months. Therapeutic enhancement factor (TEF) was defined as the ratio of thermal enhancement (TE) of tumors to TE of skin, where TE was clinically evaluated as the ratio of percent response (i.e., complete tumor clearance and moist desquamation, respectively) after combined modality to percent response after RT alone. Local tumor control was constantly better in lesions treated with any combined modalities in comparison with RT alone. The use of high RT dose per fraction appeared to increase tumor control only in the combined modalities groups, the immediate (so called "simultaneous") schedule (HT at 42.5 degrees C/45 min, applied immediately after each RT fraction, twice a week) being more effective than the delayed (so called "sequential") treatment (HT at 42.5 degrees C/45 min, delivered 4 h after each RT fraction, twice a week). The combination of high RT dose per fraction with high temperature HT (45 degrees C for 30 min) achieved the best tumor control. No increased radiation skin reaction was observed when a conventional fraction size of RT was used (3 daily fractions of 1.5-2 Gy, 4 h interval between fractions) in association with HT (42.5 degrees C/45 min, every other day, immediately after the second daily RT fraction). A remarkable enhancement of skin reaction was observed, however, when using high RT doses per fraction in association with 42.5 degrees C HT, especially with the immediate treatment schedule. No enhancement of skin reaction was obtained after high RT doses per fractions and 45 degrees C HT because an active skin cooling by means of circulating cold water was used in these cases. Consequently, a good TEF (1.58) was obtained when conventional RT doses per fraction were used in association with 42.5 degrees C HT. TEF values of 1.40 and 1.15 were observed when high RT doses per fraction were employed in association with the delayed and immediate 42.5 degrees C HT, respectively. HT at 45 degrees C can be safely employed only when tumors can be heated selectively or at least preferentially in comparison with normal tissue; in the lesions treated with such a schedule a TEF of 2.10 was obtained.

Effects of in vitro hyperthermia on murine and human lymphocytes

The effect of in vitro hyperthermia on the immune response of murine and human lymphocytes was investigated. Viability, blastogenesis and cytotoxic activity of murine lymphocytes were reduced at 39 and 42 degrees C hyperthermia. In human lymphocytes, rosette formation inhibition depended on heating-time and temperature. PHA-induced lymphocyte blastogenesis was markedly inhibited at 42 degrees C, irrespective of the duration of exposure and of the origin of the cells, although it was enhanced in some patients at 39 degrees C. Therefore, the possibility of hyperthermia-induced inhibition of the host immune response must be considered in clinical trials of total-body hyperthermia for cancer.

Magnetic induction heating of tissue: numerical evaluation of tumor temperature distributions

A one dimensional (radial) numerical model based on the bioheat transfer equation has been developed and applied to the abdomen and pelvis heated by a concentric magnetic induction electrode. This model consists of four normal tissue regions: viscera, muscle, fat and skin. Each region is assigned thermal properties characteristic of that region and power deposition values consistent with those for this mode of heating. Tumors of 2, 4 and 7 cm thicknesses are positioned in five different radial locations ranging from the central axis to the skin surface. Two blood perfusion models of the tumor are considered: the uniformly perfused model and an annular model. Tumor temperature distributions are considered acceptable if the average tumor temperature plus and minus two standard deviations lie between 42 degrees C and 60 degrees C. To stimulate practical clinical restrictions, muscle and fat temperatures are not allowed to exceed 44 degrees C, significant portions of the viscera (except for a 1 cm thick band) are not allowed to exceed 42 degrees C, and the total absorbed power required to maintain steady state cannot exceed one kilowatt. Over 100 possible cases are presented in a compact form. A conclusion drawn from this study is that with few exceptions, only small tumors in the muscle annulus are heated adequately with this modality. Large tumors will have significant unheated portions if the specified limitations are not exceeded. While this heating modality can raise the necrotic core of a tumor to high temperatures, it cannot adequately heat well perfused regions of a deep seated tumor. These conclusions are borne out clinically and are discussed in a companion paper.

Effect of hyperthermia on human melanoma cells heated either as solid tumors in athymic nude mice or in vitro

Human melanoma cells were exposed to clinically acceptable hyperthermia (42.5 degrees C) either as solid tumors in athymic nude mice or suspended in culture medium. Single cell survival was in both cases assayed in vitro in soft agar. The response to heat varied considerably among the five melanomas studied. The D0-values ranged from 21 to 590 min when the cells were heated in vitro. The response to heat following treatment in vivo was for a given melanoma larger than that following treatment in vitro. However, cells which were resistant to heat treatment in vitro, were also resistant to treatment in vivo, and those which were sensitive in vitro were also sensitive in vivo.

Effect of hyperthermia on hypoxic cell fraction in tumor

The effect of hyperthermia on the proportion of hypoxic cells in SCK mammary tumor of A/J mice was investigated. About 45% of clonogenic cells in the unheated control tumor were radiobiologically hypoxic. Upon heating with a 43.5 degree C water bath for 30 min, the proportion of hypoxic cells increased and then decreased: it was 95% at 5 hr and 60% at 12 and 24 hr after heating. Despite the increase in the proportion of hypoxic cells 5 hr after heating, the absolute number of hypoxic cells in the tumors at this time was significantly smaller than that in the unheated control tumors because of a decrease in the total number of surviving tumor cells. The initial increase in the proportion of hypoxic cells after heating may be attributed mainly to vascular occlusion. Proliferation of cells in the oxic area, and thus an increase in oxic cell number, appears to account for the decline in the proportion of hypoxic cells from 5 hr after heating.

Clinical hyperthermia: results of a phase I trial employing hyperthermia alone or in combination with external beam or interstitial radiotherapy

Forty-three patients with advanced, locally accessible neoplasms were treated in a Phase I clinical trial employing hyperthermia alone or hyperthermia combined with either high-dose-rate external beam or low-dose-rate interstitial radiotherapy (interstitial thermoradiography). All patients had failed previous conventional therapeutic attempts, including various combinations of surgery, chemotherapy and radiation therapy. Many had received tolerance or near tolerance levels of prior radiation that restricted dose prescriptions in this trial to subcurative values. A number of tumors with different histologies were treated, including squamous cell carcinoma (14), adenocarcinoma (14), melanoma (8), malignant fibrous histiocytoma (2), and sarcoma (5). The response evaluation criteria used included no response (NR--less than 50% decrease in tumor volume), partial response (PR--50% less than or equal to tumor volume reduction less than 100%) and complete response (CR--complete tumor disappearance). For all tumor types, hyperthermia therapy alone resulted in a total response rate of 45% (27% PR, 18% CR). Hyperthermia combined with high-dose-rate external beam radiotherapy yielded a total response rate of 80% (53% PR, 27% CR). Seventeen patients treated with interstitial thermoradiography displayed a 100% total response rate (29% PR, 71% CR). By tumor histologies for all treatment groups, total response rates have ranged from 50% to 79% for all types except melanoma, which has shown a 100% (8/8) response rate to date. Response durations have varied from one to 24 months. Twelve of the 43 patients remain alive; three have no evidence of disease (NED) while nine have either stable local disease or are NED in the treated volumes but have metastatic disease. Complications have been minimal and have included one third-degree burn and three second-degree burns from fringing RF fields, one vaginal-rectal fistula, a superficial focal soft tissue necrosis, and some minor blistering. The results of this Phase I trial demonstrate that hyperthermia alone or combined with radiation can be safely applied in the treatment of malignant disease. Most importantly, the data suggest that hyperthermia, especially when combined with interstitial thermoradiography, can yield remarkable results in the eradication of local cancers.

Microwave-induced hyperthermia and ionizing radiation. Preliminary clinical results

The combination of microwave-induced (2450 MHz) hyperthermia and ionizing radiation was used in 7 patients with superficial malignant tumours, which were considered refractory to other therapy. A newly developed heating system was used, allowing for a maintained temperature at the master probe of 42.5 degrees C +/- 0.5 degrees C during 45 min, but temperature measurements at multiple sites showed a marked variation. This preliminary series indicates that the combination of hyperthermia and ionizing radiation may be useful, the response rate (complete or partial) being 8 of 8 evaluable lesions. Even previously heavily irradiated sites responded. Technical improvements are highly needed to allow for controlled heating of any tissue volume.

Effect of ultrasound-induced hyperthermia and cis-diamminedichloride platinum II on murine renal function

Murine renal function was evaluated after ultrasound-induced kidney hyperthermia (42.5 degrees C and 46.5 degrees C for 35 minutes) and the administration of cis-diamminedichloride platinum II (8 mg/kg). A quantitative immunonephelometric technique was employed to determine urinary total protein (TP) and albumin (Alb) 1-180 days post-treatment. Hyperthermia of 46.5 degrees C elevated urinary TP excretion significantly more than that of 42.5 degrees C cis-diamminedichloride platinum (Cis DDP) administration greatly increase urine TP with a peak mean TP concentration of 488 microgram/ml, four days after Cis DDP (normal range was 26-48 microgram/ml). This returned to normal by day 14. The TP excretion after 42.5 degrees C hyperthermia with concurrent Cis DDP was similar to Cis DDP alone, implying there was no potentiation of early or late Cis-DDP-induced renal damage by hyperthermia. Late mouse mortality was greater (P = 0.08) after Cis DDP alone, than Cis DDP with 42.5 degrees C hyperthermia. There was a statistically significant increase (P less than 0.05) in the Alb/TP excretion ratio after the addition of 42.5 degrees C hyperthermia to Cis DDP, implying an alteration in the site or nature of the Cis DDP renal lesion by hyperthermia.

Fractionated radiation and hyperthermia: experimental and clinical studies

The effect of fractionated radiation and hyperthermia was experimentally studied in a C3H mammary carcinoma and its surrounding skin. Simultaneous radiation and heat (42.5 C-60 minutes) with one or five fractions gave thermal enhancement ratios (TER) of approximately 2.5 in both tumor and surrounding skin, and no improved therapeutic effect was obtained. Five fractions of sequential treatment with heating four hours after radiation reduced the tumor TER to about 1.4, but when 72 hours were allowed between the fractions, no thermal enhancement of the skin was observed. Thus, an improved therapeutic ratio was observed. Clinically the combined treatment was studied in 12 patients with 49 metastases from malignant melanoma treated with different schedules of radiation and hyperthermia (approximately 43 C for 30 minutes). Simultaneous treatment with three fractions in eight days gave TER values in the skin between 1.2-1.4, but a similar effect was found in the tumor. Three fractions of sequential treatment in eight days did not produce any thermal enhancement of the skin response, but still presented an apparent gain of the tumor response, and so seemed to increase the therapeutic effect. Bases on these findings, the strategy for further clinical use of combined hyperthermia and radiation is discussed.

Multiple daily fractionation (MDF) radiotherapy in association with hyperthermia and/or misonidazole: experimental and clinical results

Several modalities involving a Multiple Daily Fractionation (MDF) course in combination with hyperthermia and/or the hypoxic sensitizer misonidazole have been tested on a mouse tumor system and then applied, with the proper sequencing, to a group of patients with multiple (N2-N3) neck node metastases from H&N cancers. Different lesions of the same patients underwent different modalities. The clinical results indicate the effectiveness, in respect to a historical series of patients treated with conventional fractionation (200 rads/day, five days/week), of either MDF alone (200 + 150 + 150 rads/day, five days/week) or MDF + hyperthermia (500 MHz, 42-43 C, 45 min., after 2nd daily fraction, on day 1, 3, and 5 of each week) or MDF + misonidazole (1.2 g/m2 daily, 2 hours before 1st fraction, up to a maximum dose of 12 g/m2), or MDF + hyperthermia + misonidazole. The latter modality appears to be possibly the most effective at inducing a complete local tumor response lasting longer in time (follow-up to a minimum of four months). The pharmacology of misonidazole has been monitored in the patients to avoid undesired excessive drug plasma level. No neurological symptoms have been observed. Oropharyngeal mucositis has been observed only in patients treated with misonidazole and radiation through two cross-firing portals. The problem of selecting individual patients for a particular modality is discussed.