Combination of surgery, irradiation, and hyperthermia in treatment of recurrences of malignant tumors

Simultaneous radiotherapy and superficial hyperthermia for high-risk breast carcinoma: a randomised comparison of treatment sequelae in heated versus non-heated sectors of the chest wall hyperthermia

PURPOSE

In vitro data demonstrate that heat-induced radiosensitisation is maximised if hyperthermia and radiotherapy are given simultaneously, with the radiation fraction delivered midway through a hyperthermia session, rather than sequentially. The long-term normal tissue toxicity of full-dose simultaneous thermoradiotherapy is unknown.

MATERIALS AND METHODS

Patients with locally advanced breast cancer (T3, T4 or more than three involved nodes or local recurrence), no prior radiotherapy, received between four and eight sessions of simultaneous thermoradiotherapy. Hyperthermia always included the primary tumour site. In addition an electively heated sector (EHS) was included. The EHS was randomised to either medial or lateral to the tumour site, with the other side an irradiated but unheated control. As per our usual practice, patients received surgery and/or chemotherapy prior to radiotherapy. Radiation doses were 46-50 Gy followed by a boost of ≤16 Gy at 1.8-2 Gy per fraction. EHS and control sectors received the same dose.

RESULTS

A total of 57 evaluable cases with average follow-up of 79 months experienced two local and two nodal recurrences. There was no significant difference in ≥grade 2 toxicity for heated versus control sectors (LR χ(2 )= 0.78, p = 0.38) with no relationship between number of hyperthermia sessions and toxicity (LR χ(2 )= 2.90, p = 0.09).

CONCLUSIONS

Simultaneous full-dose thermoradiotherapy for breast cancer is feasible and well tolerated, with no significant difference in late toxicity between electively heated and unheated control sectors. All patients had hyperthermia to the primary tumour site with excellent local control.

Re-setting the biologic rationale for thermal therapy

This review takes a retrospective look at how hyperthermia biology, as defined from studies emerging from the late 1970s and into the 1980s, mis-directed the clinical field of hyperthermia, by placing too much emphasis on the necessity of killing cells with hyperthermia in order to define success. The requirement that cell killing be achieved led to sub-optimal hyperthermia fractionation goals for combinations with radiotherapy, inappropriate sequencing between radiation and hyperthermia and goals for hyperthermia equipment performance that were neither achievable nor necessary. The review then considers the importance of the biologic effects of hyperthermia that occur in the temperature range that lies between that necessary to kill substantial proportions of cells and normothermia (e.g. 39-42 degrees C for 1 h). The effects that occur in this temperature range are compelling-including inhibition of radiation-induced damage repair, changes in perfusion, re-oxygenation, effects on macromolecular and nanoparticle delivery, induction of the heat shock response and immunological stimulation, all of which can be exploited to improve tumour response to radiation and chemotherapy. This new knowledge about the biology of hyperthermia compels one to continue to move the field forward, but with thermal goals that are eminently achievable and tolerable by patients. The fact that lower temperatures are incorporated into thermal goals does not lessen the need for non-invasive thermometry or more sophisticated hyperthermia delivery systems, however. If anything, it further compels one to move the field forward on an integrated biological, engineering and clinical level.

Time and temperature dependence of MR parameters during thermal coagulation of ex vivo rabbit muscle

Detailed measurements of the T1-weighted, T2-weighted, and MT-weighted signal were performed for ex vivo muscle samples heated to various temperatures for different times. Consistent, monotonic increases in signal intensity were observed with progressive thermal coagulation, corresponding to an increase in T2 relaxation time and an increase in MT-weighted signal for temperatures above 60 degrees C. The relationship for T1 relaxation was more complex, showing a decrease in T1 relaxation from 40 to 60 degrees C and an increase above 60 degrees C. These techniques provide a more direct measure of tissue thermal coagulation than that provided by MR thermometry and suggest MR imaging strategies for the optimization and monitoring of thermal coagulation therapy protocols that create thermal damage in target tissues.

Pancoast tumour treated with combined radiotherapy and hyperthermia--a preliminary study

Six patients with Pancoast (superior sulcus) tumours were treated with combined radiotherapy and hyperthermia from April 1986 to December 1989. Radiotherapy was performed using 10 MV X-ray, and all patients received total doses of 60-74 Gy, in five fractions per week, during 5.5-15 weeks. Hyperthermia was performed once or twice a week within 30 min after each irradiation, using 8 MHz RF capacitive heating equipment (Thermotron RF-8). Partial response, defined as 50% or more regression of the tumour, was observed in four of the six patients. Three patients are alive 30, 28, and 14 months after their treatments. Radiotherapy combined with hyperthermia appears to be a promising and effective means for treating Pancoast tumours.

The response of human and rodent cells to hyperthermia

Inherent cellular radiosensitivity in vitro has been shown to be a good predictor of human tumor response in vivo. In contrast, the importance of the intrinsic thermosensitivity of normal and neoplastic human cells as a factor in the responsiveness of human tumors to adjuvant hyperthermia has never been analyzed systematically. A comparison of thermal sensitivity and thermo-radiosensitization in four rodent and eight human-derived cell lines was made in vitro. Arrhenius plots indicated that the rodent cells were more sensitive to heat killing than the human, and the break-point was 0.5 degrees C higher for the human than rodent cells. The relationship between thermal sensitivity and the interaction of heat with X rays at low doses was documented by thermal enhancement ratios (TER's). Cells received either a 1 hr exposure to 43 degrees C or a 20 minute treatment at 45 degrees C before exposure to 300 kVp X rays. Thermal enhancement ratios ranged from 1.0 to 2.7 for human cells heated at 43 degrees C and from 2.1 to 5.3 for heat exposures at 45 degrees C. Thermal enhancement ratios for rodent cells were generally 2 to 3 times higher than for human cells, because of the fact that the greater thermosensitivity of rodent cells results in a greater enhancement of radiation damage. Intrinsic thermosensitivity of human cells has relevance to the concept of thermal dose; intrinsic thermo-radiosensitization of a range of different tumor cells is useful in documenting the interactive effects of radiation combined with heat.

Time-temperature analysis of cell killing of BHK cells heated at temperatures in the range of 43.5 degrees C to 57.0 degrees C

Baby hamster kidney (BHK) cells were heated at temperatures in the range of 43.5 degrees C to 57.0 degrees C to determine the time-temperature relationship of cell killing. The cells were grown on 0.025 mm thick pieces of mylar to minimize warm-up times. After heating, the cells were plated for the colony formation assay. The endpoints of 1%, 10%, or 90% isosurvival, or the D0 values of the survival curves were used to construct plots of the logarithm of the reciprocol of the exposure time versus the reciprocol of the absolute temperature. The data for each endpoint resulted in a straight line plot, indicating that the time-temperature relationship for cell killing remained constant from 43.5 degrees C to 57.0 degrees C; namely, a 1.8-fold increase in exposure time was required for a 1 degree C decrease in temperature in order to obtain isosurvival. Heated BHK cells were also examined using electron microscopy. The threshold level of altered morphology was the dissociation of polyribosomal structure and the formation of electron-dense granules within the mitochondria. The time-temperature relationship for the induction of this altered morphology was identical to that for the 90% isosurvival endpoint. Hence, the appearance of altered morphology appears to be related to cell killing.

Tumor control in long-term survivors following superficial hyperthermia

Sixty tumors with a minimum of 1-year follow-up were treated with radiation and superficial microwave hyperthermia (915 MHz). The overall local control rate was 50% (30/60). The most important factor in outcome was appropriateness of the hyperthermia applicator. Tumors covered by at least the 25% iso-SAR contour achieved 65% local control versus 21% local control with less than 25% SAR coverage (p less than 0.01). Several measures of adequate minimum monitored tumor temperature and duration were considered. The measure best correlated with outcome was best single session time at or above 43 degrees C (t43). If each monitored tumor catheter achieved t43 greater than or equal to 30 minutes in at least one session, then tumor control was significantly (p less than 0.01) improved (63% with Min t43 greater than or equal to 30 versus 25% with Min t43 less than 30). Although there was considerable overlap between tumors with SAR greater than or equal to 25% and those achieving Min t43 greater than or equal to 30, a statistically significant (p = 0.02) difference could be demonstrated between the group meeting both the SAR and the minimum tumor time/duration standards as opposed to those meeting only one standard. The actuarial local progression-free survival for tumors most likely to have had adequate hyperthermia (defined as SAR greater than or equal to 25% and Min t43 greater than or equal to 30) and all other tumors did not begin to separate significantly until 8 to 12 months after treatment. Implications for future randomized studies are discussed.

Characteristics of the response of soft tissue sarcoma to hyperthermia: the correlation between temperature distribution, radiological examination and histology

Nineteen patients with soft tissue sarcoma were treated by a combination modality of hyperthermia and radiation or chemotherapy. There were 26 treatment sites. The size of the tumours ranged from 2.5 x 2 cm to 24 x 26 cm. Hyperthermic treatments were given twice a week, for a total of five to 14 sessions. Twenty-one tumours were treated by hyperthermia combined with radiotherapy, 2 Gy daily, five times a week, for a total of 40-78 Gy. Three tumours were treated by hyperthermia and arterial infusion of adriamycin, 100-120 mg in five or six treatments. For the superficial tumours the complete response rate was 40 per cent, and for the deep-seated tumours 6.2 per cent. Among the 12 tumours with no response, nine in which the treatment was evaluated as effective histologically (necrosis of the tumour) and by X-ray CT findings (development of a prominent hypodensity area) were included. Six cases were studied to correlate the X-ray CT findings, angiography and histological findings before and after hyperthermic treatment. The data were also used to interpret the thermal curve. The increased hypodensity area was roughly proportional to the development of necrosis, but there was one case in which hypodensity was not correlated with the necrosis. On the contrary, even in the contrast-enhanced area around the tumour in which the presence of residual tumour was strongly suspected clinically, no tumour cells were visualized. Clinical evaluation of the effect by size of the tumour can be supplemented by CT findings and histology, but should be cautiously adopted.

Re-irradiation of locally recurrent tumors with fast neutrons

Forty-six patients with locally recurrent disease were re-irradiated with fast neutrons at Fermilab. All had received prior radical radiation therapy either with or without surgery. Six were palliative. Forty patients treated with curative intent were analyzed for local response, survival, and complications. The overall response rate was 78% (31/40); 50% (20/40) had a complete local response. Ten of 16 patients (63%) with non-epidermoid carcinomas in the head and neck regions had complete response, whereas only nine of twenty patients (45%) with epidermoid carcinomas were complete responders. In a subset of 12 patients with salivary gland type tumors, 10 had a complete response (83%). Two of these 10 patients are alive beyond 5 years. Observed median survival for the forty patients was 9.3 months, and for complete responders 14.4 months. Observed median survival for partial responders was only 7.5 months. Four of six patients treated for palliation had significant subjective improvement. Significant morbidity, Grade III or greater (EORTC/RTOG scale), was seen in only 10 patients (25%), and this was found to depend directly on the total dose delivered. We conclude that neutron beam therapy can be used as a therapeutic modality for patients with recurrent tumors with an acceptable degree of morbidity.