Effectiveness of microwave hyperthermia combined with ionizing radiation: clinical results on neck node metastases

A forty-year journey from "classical" biophysics and radiobiology to hadrontherapy, space radiation and low dose rate underground radiobiology

PURPOSE

As a biologist who, since the beginning of her involvement in science, has collaborated closely with physicists, I want to share my forty years of experience describing the events that introduced me to the world of charged particle radiation biology as well as that of low doses/dose rates, with related implications in medicine and radiation protection.

CONCLUSION

The main features of my experience can be summarized in the development of an interdisciplinary culture and in the interest in technological advances for the study of biological responses to radiation in different scenarios, relevant for public health. Mine was a journey that began by chance, but which led me to a world that proved to be of great interest to me. With the current advances in science, the new generations of scientists have new opportunities that I wish them to face with the same interest and enthusiasm that I felt for such an interdisciplinary field as that of radiation biology.

Local Microwave Hyperthermia in Cancer Therapy. Preliminary Report

From February 1981 to September 1981, 16 patients (19 fields) with histologically proven malignancy (10 squamous carcinoma, 4 melanoma, 1 adenocarcinoma, 1 chordoma) were treated with hyperthermia combined with radiotherapy or chemotherapy (1 patient). There were 5 females and 11 males; average age was 65 years, range 45 to 94 years; 15 patients had a Karnofsky index greater than 50%. Hyperthermia (42.5 44.0 °C) was induced by 250 MHz to 1 GHz microwaves (BSD - 1000 Unit). Thermometry was performed by means of non-perturbing probes placed in intratumorally inserted catheters and by measurement of skin temperatures. After hyperthermia plus radiotherapy (18 fields), 9 patients showed 100% response, 5 a volume regression of more than 50%, 3 less than 50% and 1 no change. After chemotherapy plus hyperthermia, 1 patient showed no change. No significant side effects were observed (3 skin burns in 147 hyperthermia treatment sessions).

Multipronged Design of Light-Triggered Nanoparticles To Overcome Cisplatin Resistance for Efficient Ablation of Resistant Tumor

Chemotherapeutic drugs frequently encounter multiple drug resistance in the field of cancer therapy. The strategy has been explored with limited success for the ablation of drug-resistant tumor via intravenous administration. In this work, the rationally designed light-triggered nanoparticles with multipronged physicochemical and biological features are developed to overcome cisplatin resistance via the assembly of Pt(IV) prodrug and cyanine dye (Cypate) within the copolymer for efficient ablation of cisplatin-resistant tumor. The micelles exhibit good photostability, sustained release, preferable tumor accumulation, and enhanced cellular uptake with reduced efflux on both A549 cells and resistant A549R cells. Moreover, near-infrared light not only triggers the photothermal effect of the micelles for remarkable photothermal cytotoxicity, but also leads to the intracellular translocation of the micelles and reduction-activable Pt(IV) prodrug into cytoplasm through the lysosomal disruption, as well as the remarkable inhibition on the expression of a drug-efflux transporter, multidrug resistance-associated protein 1 (MRP1) for further reversal of drug resistance of A549R cells. Consequently, the multipronged effects of light-triggered micelles cause synergistic cytotoxicity against both A549 cells and A549R cells, and thus efficient ablation of cisplatin-resistant tumor without regrowth. The multipronged features of light-triggered micelles represent a versatile synergistic approach for the ablation of resistant tumor in the field of cancer therapy.

Gold nanoshelled liquid perfluorocarbon nanocapsules for combined dual modal ultrasound/CT imaging and photothermal therapy of cancer

The integration of multimodal contrast-enhanced diagnostic imaging and therapeutic capabilities could utilize imaging guided therapy to plan the treatment strategy based on the diagnostic results and to guide/monitor the therapeutic procedures. Herein, gold nanoshelled perfluorooctylbromide (PFOB) nanocapsules with PEGylation (PGsP NCs) are constructed by oil-in-water emulsion method to form polymeric PFOB nanocapsules, followed by the formation of PEGylated gold nanoshell on the surface. PGsP NCs could not only provide excellent contrast enhancement for dual modal ultrasound and CT imaging in vitro and in vivo, but also serve as efficient photoabsorbers for photothermal ablation of tumors on xenografted nude mouse model. To our best knowledge, this is the first report of gold nanoshell serving as both CT contrast agents and photoabsorbers for photothermal therapy. The novel multifunctional nanomedicine would be of great value to offer more comprehensive diagnostic information to guide more accurate and effective cancer therapy.

Unresectable primary and recurrent head and neck tumors: effect of hyperthermia and carboplatin--preliminary experience

PURPOSE

To perform a single-arm study to determine the effectiveness of and potential toxic reactions to local hyperthermia and systemic carboplatin (cis-diammine-1,1-cyclobutane dicarboxylate platinum II) for the treatment of advanced or recurrent squamous cell carcinomas of the head and neck.

MATERIALS AND METHODS

Eight patients with squamous cell carcinoma of the head and neck and stage IV disease (N2 or N3 neck adenopathy) or recurrent local-regional disease and who were previously and definitively treated were included in the study. Thermochemotherapy was administered every 4 weeks. Recorded end points were tumor response, duration of response, incidence of distant metastases, survival, cause of death, and toxic reactions.

RESULTS

One patient had a complete response to therapy, and two had a partial response. Five patients had no response or developed progressive disease during therapy. Six patients died after 4-13 months of progressive disease. Two long-term survivors received radiation therapy; one also underwent surgical resection for residual neck disease. Each thermochemotherapeutic session was well tolerated, with minimal discomfort. Toxic reactions included hypotension, vomiting, hyponatremia, anemia, thrombocytopenia, and infection at the site of administration. There were no life-threatening toxic reactions.

CONCLUSION

The combined use of hyperthermia and carboplatin shows potential in the management of unresectable head and neck tumors and is safe and well tolerated. Further studies on thermochemotherapy are warranted to assess its potential.

Outpatient interstitial thermoradiotherapy

BACKGROUND

Hyperthermia enhances the cytocidal effect of ionizing radiation. Several pilot studies demonstrated that the combination of interstitial hyperthermia and interstitial radiotherapy (interstitial thermoradiotherapy) is safe and effective. However, these studies mainly utilized low dose rate brachytherapy, and therefore, required hospitalization. With the availability of median or high dose rate brachytherapy devices, we piloted a study to evaluate the feasibility, toxicity and efficacy of interstitial thermoradiotherapy performed in an outpatient setting.

METHODS

Between 1989 and 1993, 27 patients with a diagnosis of carcinoma of the head and neck region (n = 23), carcinoma of the breast (n = 3), or malignant melanoma (n = 1) received 1 or 2 sessions of interstitial thermoradiotherapy. Median patient age was 66 years (range: 37-83 years). Treatment consisted of 60 minutes of 915 MHz microwave interstitial hyperthermia, followed by iridium-192 seed implants, either by Micro-Selectron HDR (10-12 Gray [Gy] in 8.5-21 minutes) or high activity (5-8 mCi per seed) seeds (10-15 Gy in 2-4 hours). In addition to interstitial temperature measurements, a real-time thermal camera was used to monitor the surface temperature spatial distribution. power supply and/or position of interstitial microwave applicators was adjusted when appropriate. All but one patient also received external beam irradiation prior to implants.

RESULTS

Patients tolerated treatments well although 16 (59%) of them required analgesics during hyperthermia sessions. Skin blisters or ulcerations occurred in only 6 (22%), and all but 2 healed. Complete response occurred in 24 patients (89%), partial in 3 (11%). With a median follow up of 16 months (range: 3-43 months), the 2-year actuarial local control rate was 74%.

CONCLUSIONS

The results of this study indicate that outpatient interstitial thermoradiotherapy is convenient, safe, and efficacious for treating human neoplasms.

Phase III study of interstitial thermoradiotherapy compared with interstitial radiotherapy alone in the treatment of recurrent or persistent human tumors. A prospectively controlled randomized study by the Radiation Therapy Group

PURPOSE

The objectives of this randomized trial were to determine if interstitial thermoradiotherapy (ITRT) improves tumor regression/control in accessible lesions in comparison with interstitial radiotherapy (IRT) alone and to assess the skin and soft tissue complications with either modality.

METHODS AND MATERIALS

From January 1986 to June 1992, 184 patients with persistent or recurrent tumors after previous radiotherapy and/or surgery, which were amenable to interstitial radiotherapy, were accessioned to a protocol developed by the Radiation Therapy Oncology Group (RTOG). One hundred seventy-three cases were analyzed (87 patients in the IRT group and 86 in the ITRT arm). The two arms were well balanced regarding stratification criteria. Most tumors were in the head and neck (40% in the IRT group and 46% in the ITRT group), and pelvis (42% and 43%, respectively). Eighty-four percent of patients in both arms had prior radiation therapy (> or = 40 Gy); 50% and 40%, respectively, had prior surgery, and 34% in each arm had prior chemotherapy. The dose of radiation therapy administered was dependent on the previous radiation dose and did not exceed a total cumulative dose of 100 Gy. Hyperthermia was delivered in one or two sessions, either before or before and after interstitial implant. The intended goal of the hyperthermia was to maintain a minimal tumor temperature of 42.5 degrees C for 30 to 60 min.

RESULTS

There was no difference in any of the study end points between the two arms. Complete response (CR) was 53% and 55% in both arms. Two-year survival was 34% and 35%, respectively. Complete response rate for persistent lesions was 69% and 63% in the two treatment arms as compared with 40% and 48% for recurrent lesions. A set of minimal adequacy criteria for the delivery of hyperthermia was developed. When these criteria were applied, only one patient had an adequate hyperthermia session. Acute Grade 3 and 4 toxicities were 12% for IRT and 22 % for ITRT. Late Grade 3 and 4 toxicities were 15% for IRT and 20% for ITRT. The difference was not significant.

CONCLUSIONS

Interstitial hyperthermia, as applied in this randomized study, did not show any additional beneficial effects over interstitial radiotherapy alone. Delivery of hyperthermia remains a major obstacle (since only one patient met the basic minimum adequacy criteria as defined in this study). The benefit of hyperthermia in addition to radiation therapy still remains to be proven in properly randomized prospective clinical trials after substantial technical improvements in heat delivery and dosimetry are achieved.

Thermoradiotherapy for superficial tumour deposits in the head and neck

Tumour deposits in the head and neck region were treated with hyperthermia using 915 MHz external microwave applicators and radiation therapy between 1986 and 1990. The mean (+/- SE) radiation dose was 47 +/- 2 Gy (range 21-77 Gy). All but four patients had failed previous therapy. Mean tumour volume was 40 +/- 10 cm3 (range 0.3-276 cm3). Hyperthermia was administered biweekly in 80% of the patients in 6.0 +/- 0.4 sessions (range 1-10); thermometry involved 3.6 +/- 0.4 catheters (range 1-9) and 5.7 +/- 0.4 sensors (range 1-12) per tumour. Of the 50 lesions evaluable for response, 29 had a complete response (58%), and 20 had a partial response (40%). Lesions were stratified by depth. In tumours considered potentially heatable (i.e. depth < or = 3 cm and lateral dimensions at least 2 cm less than boundary of applicator), the complete response rate was 81% (26/32, 47 +/- 2 Gy, 15 +/- 3 cm3); whereas for patients with tumours deeper than 3 cm, the complete response rate was 17% (3/18, 48 +/- 3 Gy, 110 +/- 21 cm3), p = 0.0001. Among lesions < or = 3 cm depth that exhibited a complete response, six recurred (24%, 5.8 +/- 1.8 months) while 20 lesions were recurrence free at last follow-up of 11.9 +/- 1.2 months). The overall survival of patients with lesions < or = 3 cm depth was 11.5 +/- 1.3 months (range 2.4-32.3 months) while for patients with lesions > 3 cm depth survival was 6.7 +/- 0.9 months (range 2.1-18.6 months), p = 0.01. In superficial lesions with depth < or = 3 cm, multivariate logistic regression analysis indicated that the model best correlating with complete response included radiation dose (p = 0.08) and tumour volume (p = 0.08, model p = 0.004). Multivariate proportional hazard analysis indicated that the model best correlating with duration of local control included tumour depth (p = 0.03) and previous radiation therapy (p = 0.08, model p = 0.006). Twenty-two fields were treated without any skin reactions (39%), 23 evidenced erythema (40%) and eight thermal blistering (14%). Ulceration occurred in 11 treatment fields but in all but one of these cases the ulceration may have been due to tumour breakdown as there was direct invasion of the skin by tumour prior to the initiation of treatment. The maximal skin temperature was the best predictor of morbidity although the correlation was not statistically significant (p = 0.19).

Preoperative combined treatment with radiation, intraluminal hyperthermia, and 5-fluorouracil suppositories for patients with rectal cancer

A clinical trial of a novel modality consisting of preoperative irradiation and intraluminal hyperthermia therapy, with or without 5-fluorouracil (5-FU) suppositories, was conducted on 30 patients with rectal cancer. To create hyperthermia in rectal cancer, an intraluminal electrode connected to a radiofrequency system was devised. Patients were treated preoperatively with a total irradiation dose of 30 Gy, being 3 Gy every 2 days, and 5 applications of hyperthermia given twice a week, with or without 5-FU suppositories, given as 100 mg a day to a total of 2,000 mg. Twenty patients received irradiation, intraluminal hyperthermia, and 5-FU suppositories, being the three-combination treatment, and the remaining 10 received irradiation and intraluminal hyperthermia, being the two-combination treatment. Shrinkage of the rectal cancer was observed macroscopically in 26 patients, resulting in a flattened cancerous crater or shallow ulcer. Microscopic examination revealed a marked decrease in the number of cancer cells. In fact, three resected specimens showed no evidence of cancer cells microscopically. These striking reductions in cancer size enabled us to successfully perform super-low anterior resections in four patients, with anastomoses being made just above the dentate line with a sufficiently safe margin. No serious complications were encountered in this series.

Development of lymph node and pulmonary metastases after local irradiation and hyperthermia of footpad melanomas

C57BL/6 mice with syngeneic B16-F10 melanomas were treated 7 days after tumor inoculation into the footpad with local hyperthermia (HT) of 43.5 degrees C for 90 min. A combination of local 30 Gy X-irradiation (XRT) given 2, 4 or 12 h after HT cured the primary tumor in 34/35 mice, with irreversible damage to normal foot tissues in most of the animals. When 7.5, 10 or 15 Gy XRT were delivered 4, 18 or 24 h after HT, there were only a small number of cures and also a much smaller incidence of irreversible normal tissue damage. HT alone resulted in a significant (P less than 0.001) increase in metastases to regional lymph nodes (RLN) and the lungs. The 'curative' doses of combined XRT and HT resulted in a significant (P less than 0.001) decrease in metastasis to RLN and to the lungs. Conversely, subcurative doses of combined therapy resulted in an increase in RLN and lung metastasis (P less than 0.001). Abdominal lymph node metastasis, not usually seen in control mice, is markedly increased after HT alone or in combination with subcurative XRT (P less than 0.001). The overall survival of mice treated with HT alone is decreased (P less than 0.0028). The survival of mice treated with HT followed 4, 18 or 24 h later with 10 Gy XRT is further decreased (P less than 0.0025). These data show that subcurative HT, or XRT plus HT, increases the incidence of spontaneous metastasis in this syngeneic mouse melanoma model. Curative doses prevent this effect on metastasis, but there is an unacceptable incidence of irreversible damage to the tumor-bearing foot. The cause(s) of this phenomenon are not known.

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.

Advances in radiation therapy for head and neck cancer

Radiation therapy either as a single modality or as part of multimodality plans remains an integral part of curative treatment for cancers of the head and neck. This paper traces the modernization of radiation therapy regarding tumors of the head and neck using examples of sites of malignancy where radiation therapy is the sole modality or where radiation therapy can be combined with surgery and chemotherapy for optimal results. As local-regional control rates have improved with the use of combined radiation therapy and surgery and aggressive hyperfractionation schemes for advanced primary tumors, distant metastases and second primary neoplasms are now accounting for a larger proportion of treatment failures. Until such time as more effective systemic therapy and cancer control mechanisms are developed to address these problems, radiation therapy will continue to play a major role in the overall management of patients with cancers of the head and neck.

Localized current field hyperthermia: effect on normal ocular tissue

Using a 500 kHz radiofrequency electromagnetic heating system, the effects of localized current field hyperthermia in normal rabbit eyes were examined. A specially designed scleral plaque placed on normal rabbit eyes was heated to temperatures of 43 degrees C, 45 degrees C, and 47 degrees C for a period of 45 min. The effects of hyperthermia were monitored by clinical examination, fluorescein angiography, electroretinography and histopathology. A graded effect with increasing temperature was found at the lower temperature, and it was confined to the treatment field. At 47 degrees C the electroretinogram was extinguished due to diffuse photoreceptor damage outside the treatment field, as demonstrated by histopathology and electron microscopy. This study indicates that hyperthermia at 45 degrees C for 45 min is the maximum allowable temperature without causing diffuse retinal damage in the normal rabbit eye.

Interstitial thermoradiotherapy for recurrent head and neck cancer

From 1985 to 1987, 22 head and neck sites in 20 patients with recurrent tumors were treated with interstitial thermoradiotherapy (ITRT). The sites treated were 15 neck (68%), four tongue (18%), two parotid (9%), and one buccal mucosa (4%). Squamous cell carcinoma was diagnosed in 21 sites and adenocarcinoma in the other. All patients had prior radiotherapy (RT), including 15 who underwent a combination of RT and surgery. Interstitial RT with iridium 192 (mean dose, 40 Gy) was combined with interstitial microwave hyperthermia (mean thermal dose, 90 units). Complete response (CR) was obtained in 15 (68%) sites and partial response (PR) in seven (32%) sites. There were no local recurrences in the 15 CR patients during a period of observation of up to 30 months. Of the seven PR patients, one had radical neck dissection and is free of tumor after 28 months. Tumor volume was an important factor influencing CR (P less than .001), whereas RT and thermal dose were not (P = .3). Of the 20 patients treated, 19 experienced major subjective benefit. Serious complications occurred in two patients: one had localized soft tissue necrosis, the other had aspiration pneumonia. ITRT was well-tolerated by patients despite prior aggressive therapy. High objective response rate and low toxicity demonstrate the value of this treatment combination in the management of patients with postradiation recurrence of head and neck tumors.

Hyperthermia in combination with definitive radiation therapy: results of a Phase I/II RTOG Study

Between August 1981 and April 1986, 133 patients with superficial malignant tumors not previously treated with radiotherapy were entered on a Phase I/II RTOG study evaluating hyperthermia plus definitive radiotherapy. Eligible patients included those with superficial epithelial or mesenchymal tumors less than 4 cm in depth. Protocol radiotherapy specified a tumor dose of 60 Gy delivered in 1.8-2.0 Gy fractions 5 times/week with a boost of 5-10 Gy through reduced portals to residual tumor. Protocol hyperthermia, delivered twice weekly, was to start within 15 minutes following irradiation and to consist of 60 minutes of heat to a tumor temperature of 43 degrees C. Sixteen patients were excluded. Of the 117 eligible patients, the treated lesions had site/histologies which were 35% head & neck/squamous, 46% breast/adenocarcinoma, and 19% other site/histologies. Lesions were 3 cm or larger for 77% of patients. Of the 41 patients with head & neck/squamous lesions, skin or subcutaneous necrosis occurred within 6 months for 2% of the patients; 12% experienced thermal blisters. Fourteen patients were followed for 6 months or more following start of treatment; none of these experienced late toxicities more severe than telangiectasis. Complete responses were observed in 51% of these patients. Of the 54 patients with breast/adenocarcinoma lesions, skin or subcutaneous necrosis occurred within 6 months for 13% of the patients; 17% experienced thermal blisters. Thirty-seven patients were followed for 6 months or more following start of treatment; complications observed during this period included 13% with ulceration and one case of skin necrosis. Complete responses were observed in 85% of these patients. Local control was maintained at nearly this level for at least 2 years. Logistic regression analyses showed site/histology, greatest tumor diameter and average tumor temperature to be significantly related to response. Based on these promising findings, the RTOG has instituted a randomized Phase III study evaluating radiation therapy with or without hyperthermia in this patient population.

Interstitial thermoradiotherapy for recurrent or persistent tumours

Between 1984 and 1986, 31 sites in 27 patients with biopsy proven tumours were treated with a combination of interstitial microwave hyperthermia (HT) and iridium 192 implants (RT). The 31 sites treated included fifteen (48 per cent) head and neck, six (20 per cent) breast, four (13 per cent) vagina and cervix, and six (20 per cent) others. All patients had prior surgery, RT, or chemotherapy. Of the 31 sites treated, 19 (61 per cent) had complete response (CR) with no recurrence in the volume treated. Additionally, eight patients remained free of tumour from 3 to 24 months. Partial response (PR) was seen in 11 (36 per cent) sites while one (3 per cent) had lesser degree tumour regression. Tumour control rate correlated well with the dose of radiation, p = 0.02, and tumour volume, p = 0.02, but not with thermal dose. Treatment complications of significance occurred in one (3 per cent) site, which developed soft tissue necrosis. This study again has demonstrated the effectiveness of RT-HT combination in treatment of recurrent tumours.

Laserthermia on head and neck malignancies--experimental and clinical studies

In recent years, remarkable progress has been made in thermotherapy. However, there is little information on localized laser hyperthermia (laserthermia) or on conventional hyperthermia technique applied to head and neck cancers. We have developed a ceramic probe to insert into tumor tissue and irradiate the Nd:YAG laser omnidirectionally. This probe can heat a spherical range of 1.5 cm to 43 degrees C. This paper concerns experimental and clinical studies on the effectiveness of laserthermia using our technique in the tumor of head and neck regions. The results obtained were as follows: histological findings and biochemical studies of arachidonic acid metabolites on normal rabbit tongue after laserthermia showed very slight effect and relatively short duration of the concomitant inflammation. The combination of laserthermia and CDDP chemotherapy was found to give a much better cytocidal effect on the tumor tissue in nude mice implanted with human thyroid cancer cells. In a clinical study on 21 cases with head and neck cancers, four cases showed complete and 13 cases showed partial remission after combined treatments of laserthermia and radiochemotherapy. Both basic experimental and clinical results have indicated a role for laserthermia in the treatment of head and neck cancer. Possible uses include the treatment of early cancer as well as advanced or recurrent cancer, where its therapeutic effect may be increased by combination with radiotherapy or chemotherapy.

Results of a non-controlled trial of hyperthermia combined with radiation for superficial tumours

Fifty-four patients with 65 superficial malignant lesions were treated by local hyperthermia combined with radiation therapy at the National Cancer Center Hospital, Tokyo. Hyperthermia was delivered with an Aloka Model HMS-020 (2450 MHz) or with a horn-type applicator of BSD-1000 (80-90 MHz). Relatively small tumours, those less than 4 cm in thickness, were treated by using 2450 MHz while 80-90 MHz delivered through the horn-type applicator was used for tumours exceeding 5 cm in thickness. The radiation dose was 4 Gy twice a week or 2 Gy five times a week, the total dose being 40-60 Gy. A total of six to 10 hyperthermia treatments ranging from 40 to 60 min each, with the tumour heated to more than 42.5 degrees C, were given twice a week within 1 h following radiation therapy. Complete response was achieved in 16 of the 30 patients (55 per cent) treated with the 2450 MHz microwave, and partial response in seven others (23 per cent). Tumours treated with the BSD-1000 achieved complete response in 10 out of 33 patients (30 per cent) and partial response in nine others (27 per cent). In five out of nine patients classified as partial responders, however, complete disappearance of tumour cells was noted by post-treatment histological examination. Complete plus partial response rates were thus essentially the same with the Aloka HMS-020 and the BSD-1000, though the rate of complete response was apparently higher with the Aloka unit, probably because it was used on smaller tumours.

Radiotherapy and hyperthermia. Analysis of clinical results and identification of prognostic variables

Site- and tumor-specific data obtained from two groups of patients with head and neck and melanoma lesions, respectively, showed that both immediate response and response duration were enhanced by the addition of heat. Two important variables, however, such as tumor volume and "isoeffect thermal dose" appeared to influence local tumor control. The volume effect was less pronounced in the lesions treated with radiotherapy plus heat than in those treated with radiotherapy alone, suggesting that the addition of heat was more damaging to the large than to the small lesions. Furthermore, a striking isoeffect thermal dose-response relationship was shown in head and neck lesions. Those data were collected and used to design a mathematical model relating the probability of local control to clinical and treatment variables. The analysis shows that, by using the same radiation parameters, the probability of local tumor control is a function of both "isoeffect thermal dose" and tumor volume.

Microwave hyperthermia as an adjunct to radiation therapy: summary experience of 256 multifraction treatment cases

Results in 256 cases of malignant disease treated by multifraction combination hyperthermia-radiation therapy under the supervision of one physician are presented. The overall response rate was 94% including a 62% complete response. Complications specifically ascribed to hyperthermia were minor, and most side effects of combined treatment were radiation dose related. Tumor response was somewhat better for chest wall recurrence (72% CR) and for adenocarcinoma in general (64% CR), but no significant dependence on tumor site or type was found. Most patients were treated with low dose external radiation with hyperthermia given by air cooled microwave applicators or intracavitary antennae operating at 915 or 300 MHz, and some by interstitial microwave antennae plus 192 Ir. Results appeared to be independent of the microwave source employed. Response did depend on radiation dose: complete response rate with 4000 rad was 65%, and with 2000 rad was 42%.

Regional outcome in oropharyngeal and pharyngolaryngeal cancer treated with high dose per fraction radiotherapy. Analysis of neck disease response in 1646 cases

Out of a series of 1666 consecutive patients with squamous cell carcinoma of oropharynx and pharyngolarynx, 1646 were evaluable at a 3-year interval following radical radiation therapy. The actuarial 3-year nodal control rate using the AJC classification was: N0 98%, N1 90%, N2 88%, N3 71% when the primary was controlled. The regional outcome is influenced by clinical features such as nodal size, multiplicity and fixity. Cervical recurrence frequency is higher for pharyngolaryngeal carcinoma than for oropharyngeal cancer. The impact of the treatment planning on regional control is discussed. Due to the of concomitant boosting of nodes, cervical metastases were treated according to a type of accelerated fractionation schedule with weekly doses of 12-15 Gy for a total of 70-85 Gy in 75% of the cases. Clear-cut dose control relationships are demonstrated for nodes larger than 3 cm in diameter. Overboosting residual cervical disease fails to yield a better nodal control. Comparative analysis is established between results obtained with this high dose per fraction radiotherapy schedule, conventional regimens of irradiation and other new approaches, combining chemical and physical agents. Therapeutic implications are also derived to define adequate field coverage.

Management of advanced stage squamous cell carcinoma of the head and neck

Squamous cell tumors of the head and neck make up 5% of tumors diagnosed in this country. The combination of excessive tobacco and alcohol use is the most common causative factor for these tumors. Their natural history is characterized by a tendency for early local-regional recurrence and the late appearance of distant metastases. A significant proportion of patients present with advanced (stage III or IV) disease, which has a poor prognosis when treated with surgery and radiotherapy. The use of adjuvant chemotherapy with surgery and radiotherapy in previously untreated patients holds promise for improving cure rates in patients with this disease. The use of chemotherapy in patients with recurrent head and neck tumors results in response in approximately one third of patients. The majority of these responses are partial and short-lived, but those patients achieving a complete remission appear to have a significant prolongation of survival. The combination of chemotherapy and radiotherapy in patients with advanced disease is being tested in a number of trials. It is hoped that this combination will increase the response rate and result in prolonged survival.

N3 (TNM-UICC) metastatic neck nodes managed by combined radiation therapy and hyperthermia: clinical results and analysis of treatment parameters

In an attempt to improve the control of N3 (TNM-UICC) fixed and inoperable metastatic nodes, local microwave hyperthermia (HT) was combined with radiation therapy (RT). From February 1981 to January 1985, 34 patients, with N3 metastatic nodes from primary tumours in the head and neck, were treated according to two different prospective, non-randomized protocols: 23 patients received HT combined with the first course of conventionally fractionated radical RT (40 Gy + HT--2 week interval--20-30 Gy), and 11 patients received HT combined with palliative RT (20-50 Gy + HT). All the patients were treated with the same microwave applicator (MA-150) on the BSD-1000 unit, at a frequency of 280-300 MHz. Temperatures were measured by means of 2-3 Bowman probes placed within the tumour (core and periphery) and 5-6 probes on the skin surface. HT sessions were delivered after RT (less than 20 min), 2 or 3 times weekly, for a duration of 30 min after steady-state temperatures were obtained. Twenty-seven patients out of 34 were evaluable, with a follow-up of at least 3 months (range 3-39 months; median 10 months). Clinical results at 3 months revealed 59 per cent complete responses, 30 per cent partial responses, and 11 per cent with progressive disease. Analyses of response rates showed: a marginally significant difference (P = 0.095) between RT alone (historical control) and the entire group of patients treated with RT plus HT; a significant difference (P = 0.034) if RT alone is compared with Protocol A (RT greater than or equal to 60 Gy + HT); no significant difference between the two protocols employing HT, despite the different RT doses utilized; no significant differences in response rates, as a function of minimal intratumoural temperatures achieved, number of weekly HT sessions or total number of HT sessions; and a significantly lower response rate for nodes with maximum diameter greater than 6 cm (P = 0.043). No important differences in acute side effects between irradiated and heated regions in the same patient were noted. Late side effects in patients treated with RT plus HT included three cases (9 per cent) of severe fibrosis, possibly as a consequence of excessive maximum tumour temperature (greater than 46 degrees C).

Site and disease selection for hyperthermia clinical trials

Significant progress has been made in the past 20 years in understanding the biological basis of hyperthermia-induced cytotoxicity, thermoenhancement of radiation therapy and chemotherapy, and in the development of clinically applicable microwave, radiofrequency, ultrasound and thermometry equipment. Numerous uncontrolled trials have suggested strongly that hyperthermia in conjunction with radiation therapy or chemotherapy may contribute to improved local control rates for recurrent or metastatic cancer without excessive morbidity. Carefully designed and well-controlled site and disease-specific prospective randomized trials with standardized hyperthermia and radiation therapy techniques, adequate thermometry, precise end points for tumour control and normal tissue toxicity are now essential to establish the role of hyperthermia in cancer management. Criteria for tumour site selection will be explored for trials employing radiation therapy and local-regional hyperthermia. Examples of sites selected will be presented which represent areas that can, with current technology, usually be adequately heated, and in which significant patient benefit may result from improved local-regional control.

A clinical microwave hyperthermia system with multipoint real-time thermal dosimetry

A clinical hyperthermia system using a 915 MHz microwave generator and incorporating multipoint thermocouple thermometry is described. Temperatures can be monitored simultaneously at 16 points and measurements displayed on a visual display unit and a plotter. The power output of the generator is adjusted under computer control to maintain a constant predetermined temperature in a chosen control channel. A clinically useful feature of the system is the ability to determine the effective cumulative thermal dose delivered to the tissue at points monitored in real time. The basis for the thermal dose calculation is discussed in detail. The calculated dose parameter is displayed for each of the 16 channels during the treatment and updated every 30 s. This real-time display of a thermal dose parameter has made possible a more homogeneous heating of tumours.

Tumour response to heat and radiation: prognostic variables in the treatment of neck node metastases from head and neck cancer

A total of 38 patients with 81 multiple neck node metastases from squamous cell carcinoma of head and neck were treated with radiotherapy alone or with radiotherapy plus hyperthermia. Irradiation was delivered following a three fractions per day schedule of 2 + 1.5 + 1.5 Gy/day, with 4 h intervals between fractions, up to a total dose of 60 Gy. Heat was applied by means of a 500 MHz apparatus. Temperature data were converted to equivalent minutes at 42.5 degrees (Eq 42.5). Initial complete response rates and local control distribution were compared for subgroups of tumour volume and thermal dose. The data indicated that the volume effect was less pronounced in the combined modality than in the radiation alone arm, suggesting that the addition of heat was more damaging to the large than to the small lesions. A striking thermal dose-response relationship was shown, although complete response rates increased only after a certain thermal dose was accumulated, clearly indicating the presence of a threshold dose.

Effects of sequencing of the total course of combined hyperthermia and radiation on the RIF-1 murine tumor

The optimal sequence for clinical utilization of combined radiotherapy and hyperthermia is not known. The clinical trials have resulted in similar responses whether hyperthermia is given before or after radiation. Moreover, studies addressing the best sequence for an entire course of multifractionated hyperthermia and radiation are lacking. In these experiments, the importance of sequencing of heat and irradiation in a multifractionated treatment regimen in RIF-1 murine tumors was studied. It was observed that a close sequence of heat and irradiation is more beneficial than separate cytotoxic action. When heat and irradiation were given simultaneously, (within 1 hour) 67% to 75% of the tumors were cured. Heat and irradiation given sequentially (the entire course of one following the entire course of the other, each separated by 72 hours) cured 20% of the tumors. No tumors were cured when treated with heat or irradiation alone. The tumor regrowth time (mean tumor doubling time) is much longer in simultaneous treatment than in sequential treatment. It appears that heating first decreases the effectiveness of subsequent irradiation, causing a shorter growth delay than the opposite sequence. Heat alone does not alter the tumor bed permanently, but irradiation seems to do so, resulting in a slower rate of growth upon recurrence.

Clinical results of radiofrequency hyperthermia combined with radiation in the treatment of radioresistant cancers

Clinical results of radiothermotherapy applied to 40 radioresistant tumors in 36 patients were reported. Hyperthermia was administered locally using two radiofrequency (RF) capacitive heating equipment systems developed in our institution under the collaboration of Yamamoto Vinyter Co. Ltd. Hyperthermia was given twice weekly immediately after irradiation. Intratumor temperatures of 41 degrees C to 44 degrees C were maintained for 30 to 60 minutes. Radiation doses varied from 32 Gy to 60 Gy. Of the 40 tumors treated, 21 (53%) showed complete response, 16 (40%) partial response, and 3 (7%) no response when the tumor response was assessed by tumor size measurement. Of eight patients who had matched tumors treated with either radiation alone or radiation plus hyperthermia, six patients showed better response in tumors treated with radiothermotherapy than in tumors treated with radiation alone. Skin reactions following radiothermotherapy and radiation alone were comparable. The tumor response was greatly dependent on the tumor size. Greater response was observed in small tumors, although histologic examinations and long-term follow-up studies revealed an excellent effect of radiothermotherapy on the large tumors as well as on the small tumors. Tumor responses correlated with tumor center temperatures but not with histologic features. Our clinical results indicate that RF hyperthermia combined with radiation has a therapeutic benefit in the treatment of radioresistant cancers.

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.

Physiological mechanisms in hyperthermia: a review

In experimental animal systems, hyperthermia at therapeutic temperature (43-45 degrees C) causes a profound increase in blood flow in normal tissues while it induces only meager and temporal increases in blood flow in tumors. A severe vascular occlusion and hemorrhage usually follows the increase in blood flow in the tumors at the above temperatures. Another pronounced physiological change in tumors by heat is a prompt decrease in intratumor pH. The decrease in intratumor pH would accentuate the thermokilling of tumor cells and also possibly inhibit repair of thermodamage and development of thermotolerance in tumors. The temperature in tumors may rise higher than that in normal tissues during heating because of inefficient heat dissipation from the tumor as a result of decrease blood flow or vascular occlusion. Thus, the differential effects of heat on vascular function and pH in tumors and normal tissues may result in a greater damage in tumors than in surrounding normal tissues. Further investigation is urgently needed to find out whether similar physiological changes occur in human tumors and normal tissues by hyperthermia.

Clinical results of irradiation combined with local hyperthermia

This report updates a previous publication describing the experience at the Mallinckrodt Institute of Radiology with irradiation and hyperthermia in the treatment of superficial metastatic and recurrent malignant tumors. In a dose-seeking Phase I-II clinical study, a total of 101 lesions have been treated. Twenty-two tumors were treated with doses of irradiation ranging from 1000 to 3000 rad and the rest with doses between 3000 and 4000 rad. Irradiation was delivered twice weekly (every 72 hours) in tumor doses of 400 rad, usually with electrons (9-16 MeV). Hyperthermia was initiated within 30 minutes following irradiation, most of the patients being treated with 915 MHz microwaves, 41-43 degrees C, for 60-90 minutes every 72 hours. Adequate temperatures were reached in most lesions measuring less than 2 cm in thickness, 70% of those 2-4 cm and only in 30% of those thicker than 4 cm. Of 36 measurable lesions in the head and neck, 20 had a complete response and 12 a partial response. In 16 of the 20 patients (80%) showing a complete response the tumor was controlled from three to 36 months. Of 30 adenocarcinoma of the breast lesions, recurrent in the chest wall, 16 showed a complete response and 9 a partial regression. Twelve of the 16 lesions that regressed completely (71.4%) showed long-lasting tumor control. Of 22 metastatic or recurrent melanoma lesions, 16 had a complete regression and six a partial response. Of the 16 patients with complete response, 13 (81%) had no evidence of recurrence lasting from three to 36 months. Three sarcoma lesions responded well to the combination of irradiation and heat and did not recur after treatment. Patients treated with doses larger than 3000 rad in the head and neck or in the chest wall (epidermoid carcinoma or adenocarcinoma, respectively) showed better tumor response than those treated with lower doses. However, in melanoma satisfactory results (80% or higher response) were observed with doses as low as 2000 rad. This combined therapy has been well tolerated by the normal tissues. In 6% of the patients there was evidence of tumor necrosis with ulceration and in 5% thermal burns which healed after 2 to 3 months, with conservative management.(ABSTRACT TRUNCATED AT 400 WORDS)

Hyperthermia in combination with radiotherapy: a review of five years experience in the treatment of superficial tumors

Facilities for regional tumor hyperthermia has been in use at RPMI since 1976, and have been routinely used to treat patients according to protocol since 1977. Hyperthermia delivery has been exclusively by microwave using 434 MHz, 915 MHz and 2450 MHz. Greatest success at reaching tumor temperatures of 43-44 degrees C with minimal skin heating was obtained using 915 MHz. The majority of the patients were treated with this frequency. Approximately 125 patients have been treated and 70 have achieved completion of therapy and follow-up. Follow-up has been at least one month and several patients have been followed for one to two years. Initially, for entry into the hyperthermia protocol, patients were required to have three or more lesions. One lesion on each patient was treated with 800 rad fractions repeated three times on a 72 hour schedule. The second lesion was treated with 700 rad fractions and the third with 500 rad plus hyperthermia on the same schedule. Twelve patients with multiple melanoma lesions completed this study. One of 12 patients showed no response to the combination of hyperthermia plus radiotherapy, while four showed no response to radiotherapy alone. Of eight patients who survived three months, all lesions treated by hyperthermia plus radiotherapy responded completely, while only five lesions treated by radiotherapy alone so responded. In a second study, 58 patients with superficial tumors were treated by a protocol where hyperthermia was added to optimal conventional radiotherapy. Of the total, 43 patients had complete tumor response at follow-up varying from one month to 18 months. A subgroup of 24 of these patients had two lesions, one of which was treated with hyperthermia in addition to radiotherapy while the other served as control, receiving radiotherapy only. Nineteen lesions demonstrated complete response to hyperthermia plus radiotherapy, while only 14 of the controls had complete response. None of the lesions treated with hyperthermia responded less well than those treated by radiotherapy alone. Morbidity, as measured by skin reaction, was rarely increased in the heated field.

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.

Normal tissue response to localized deep microwave hyperthermia in the rabbit's prostate: a preclinical study

Experiments were performed to determine the response of normal tissues of the rectal cavity and the prostate to localized 2.45 GHz microwave deep hyperthermia. Hyperthermia at 43 degrees C was delivered by means of a coaxial probe in the rectal cavity for 30 min. once or twice at an interval of 2 days. Normal tissues of the rectum, urinary bladder, and prostate were histologically examined up to three months after treatments. In almost all of the treated animals no tissue and organ injury resulted from localized deep hyperthermia at 43 degrees C. This treatment appears to be safe for the treatment of carcinoma of the prostate.

Does local tumour heating im mice influence metastatic spread?

Experimental studies are reported on the effect of local tumour hyperthermia, combined with radiation, on the incidence of distant metastases. Two types of study were performed: a retrospective analysis of data obtained incidentally from regrowth delay experiments, and prospective studies designed specifically to investigate the effect of heat on the spread of disease. In the first case, tumours were treated with a range of palliative doses of X rays given either alone or in combination with heat (42.8 degrees C/h). Only one tumour out of 5 showed a significantly increased incidence of metastases, and then only when heated immediately before radiation. The prospective studies were designed so that primary tumours were locally controlled. Neither heat applied immediately before nor after irradiation resulted in a significant change in incidence of metastases. However, whole body heating did produce a marginally significant increase. Fractionated hyperthermia (4 heat doses plus curative radiation) did not result in any significant change in frequency of metastasis. These data suggest that local heating combined with radiation does not result in an increased risk of metastatic spread.

Regional hyperthermia for cancer

The clinical use of regional hyperthermia combined with radiation therapy, chemotherapy, or both in 107 patients with advanced cancer is reported. Surgery was subsequently carried out in eight patients. The radiofrequency equipment used is capable of heating tumors at any depth with few adverse side effects. Complete responses to therapy occurred in 16 percent of patients, and partial responses in 52 percent. Striking pain relief was observed in both responders and nonresponders.

Technique for microwave-induced hyperthermia in superficial human tumours

In order to induce local hyperthermia in superficial tumours a computer system using a 2,450 MHz microwave generator connected to a circular (diameter 90 mm) direct contact applicator was constructed based on invasive temperature control. Small thermistor probes with a diameter of 0.6 mm are inserted in the tumour and surrounding tissues. Eight thermistors can be used simultaneously and one of them is chosen as the "master'. The automatic control system used a pulsed irradiation technique to avoid the problem with interactions between the metallic wires of the temperature probe and the electromagnetic field. With the system it was possible to control the temperature at the master thermistor within +/- 0.5 degrees C from the preset value.