Radiation therapy and hyperthermia in the treatment of superficial lesions: preliminary analysis: treatment efficacy, and reaction of skin, tissues subcutaneous

A Systematic Review of Primary, Adjuvant, and Salvage Radiation Therapy for Cutaneous Squamous Cell Carcinoma

BACKGROUND

The gold standard of treatment for cutaneous squamous cell carcinoma (cSCC) is surgery radiation therapy (RT) is used selectively as definitive treatment for low-risk tumors or as adjuvant/salvage treatment for high-risk tumors. There is a lack of standardized studies evaluating the efficacy of RT in either clinical scenario.

OBJECTIVE

To determine the efficacy of primary and adjuvant/salvage RT for the treatment of cSCC.

MATERIALS AND METHODS

A systematic review of PubMed, Embase, Cochrane, and Web of Science was performed for studies that reported outcomes of cSCC treated with RT to the primary site alone. Outcomes included local control (LC), local recurrence (LR), nodal metastases (NM), distant metastases (DM), disease-specific death (DSD), and recurrence-free survival (RFS).

RESULTS

Forty-six studies with 4,141 tumors were included. Pooled LC and LR rates were 87.3% and 8.6%, respectively. The rates of NM, DM, DSD, and RFS were 4.8%, 3.5%, 5.3%, and 73.5%, respectively. Local recurrence was significantly higher for T3 and T4 tumors, with rates above 25.9%.

CONCLUSION

LR after RT to the primary site increased with increasing tumor stage, highlighting the importance of clear surgical margins for high-risk tumors. Prospective randomized studies characterizing outcomes by tumor stage for RT compared with surgery are needed to inform guidelines.

Biological rationale and clinical experience with hyperthermia

Hyperthermia (HT) as an adjunct to radiation therapy (RT) has been a focus of interest in cancer management in recent years there have been numerous randomized and nonrandomized studies conducted to assess the efficacy of HT combined with either RT or chemotherapy especially in the treatment of superficially seated malignant tumors. The major impact of HT is currently on locoregional control of tumor. Heat may be directly cytotoxic to tumor cells or inhibit repair of both sublethal and potentially lethal damage after radiation. These effects are augmented by the physiological conditions in tumor that lead to states of acidosis and hypoxia. Blood flow is often impaired in tumor relative to normal tissues, and HT may lead to a further decrease in blood flow and augment heat sensitivity. Three major areas of clinical investigation have borne the greatest fruit for HT as adjunctive therapy to RT. These include recurrent and primary breast lesions, melanoma, and head and neck neoplasms. Thermal enhancement ratio was increased in all cases and is approximately 1.4 for neck nodes, 1.5 for breast, and 2 for malignant melanoma. In general, the most important prognostic factors for complete response (CR) are RT dose, tumor size and minimal thermal parameters minimal thermal dose (t43min), mean minimal temperature (Tmin) or T90, i.e., temperature exceeded by 90% of thermal sensors]. The number of HT fractions administered per week appears to have no bearing on the overall response, which may be indicative of the effects of thermotolerance. The total number of HT fractions delivered also appears irrelevant provided adequate HT is delivered in one or two sessions. The major prognostic factors for the duration of local control were tumor histology, concurrent RT dose, tumor depth and Tmin. Although numerous single institution studies showed increased CR rates and improved local control, the efficacy of HT as an adjunct to RT should be assessed with well-designed multi-institutional randomized clinical trials. Such clinical trials are underway.

Predictive factors for skin reactions in patients treated with thermoradiotherapy

In this study we performed univariate analyses to analyse the predictive factors for skin reactions, i.e. erythema, thermal blisters and ulceration, that occur during thermoradiotherapy. One hundred and twenty-six fields in 126 patients were treated with thermoradiotherapy using 915 MHz external microwave hyperthermia. Mean age of patients was 62 years. All but 11 lesions received previous therapy. Prior treatment included surgery (75%), chemotherapy (60%) and/or radiation therapy (51%). The mean previous radiation dose was 54 +/- 2 Gy. The concurrent tumour radiation dose was 45 +/- 1 Gy, in 16 fractions, over 35 elapsed days (dose per fraction of 1.6-4.8 Gy). The mean number of heat sessions administered was 5.5 +/- 0.2 (range 1-14). In 83% of cases hyperthermia was administered biweekly. Forty-two patients were treated without any skin reaction (33%), erythema occurred in 59 fields (47%), transient thermal blisters occurred in 25 fields (20%) and ulceration occurred in 23 fields (18%). In 25 cases, two or more skin reactions (20%) were observed concurrently. Concurrent radiation dose correlated with skin reactions (p = 0.02). The incidence of skin reactions was inversely correlated with previous radiation therapy (p = 0.04) and previous radiation therapy dose (p = 0.04) possibly due to fibrosis. None of the tumour or skin thermal parameters correlated with the reaction rate.

Response of canine soft tissue sarcomas to radiation or radiation plus hyperthermia: a randomized phase II study

Sixty-four dogs with spontaneous soft tissue sarcomas without evidence of metastases were stratified by tumour volume and randomized to receive graded doses of radiotherapy (XRT) alone or radiotherapy plus hyperthermia (HT). An improvement in duration of local control was achieved with the addition of hyperthermia as compared with XRT alone (Wilcoxon, p = 0.040; log rank, p = 0.064). Overall frequency of late complications was not different for the two treatment arms when comparing across equivalent XRT dose groups. Frequency of distant metastases after therapy completion was not significantly different for the two treatment arms at 1 year (7.4% for XRT versus 20% for HT plus XRT) or 2 years (11.5% for XRT versus 25% for HT plus XRT) post therapy. These results suggest that a therapeutic gain was achieved for this group of tumour-bearing animals. Uni- and multivariate analyses were performed to examine the potential for various factors to influence treatment outcome. Patient related variables included tumour stage, histologic subtype and grade and tumour site. Treatment related variables included total radiation dose and 15 descriptors of temperature distributions achieved during hyperthermia. When considering patient related factors, tumour histology, grade and location were important predictors of time to minimum volume, but only tumour location influenced time to tumour regrowth. When considering treatment related factors, radiation dose was not significantly correlated with time to minimum volume or time to local regrowth, but it was correlated with probability for late normal tissue damage in the XRT alone group (p = 0.005). For the hyperthermia treatments, 13 of 15 tumour temperature distribution descriptors were correlated with time to minimum volume, but none were correlated with time to local regrowth. These results suggest that caution should be used in interpreting the value of temperature distribution descriptors in predicting for long-term local control after hyperthermia and radiotherapy, based on analysis of short-term responses.

Parameters predictive for complications of treatment with combined hyperthermia and radiation therapy

Pretreatment and treatment related factors were reviewed for 996 hyperthermia sessions involving 268 separate treatment fields in 131 patients managed with hyperthermia for biopsy confirmed local-regionally advanced or recurrent malignancies to ascertain parameters associated with the development of complications. A subset of 249 fields were identified in which multipoint or mapped temperature data were available for at least one treatment session per field. A total of 198 fields involved superficially located tumors (less than or equal to 3 cm from the surface), whereas 51 fields involved more deeply located tumors. Most of these patients had received extensive prior therapy: 77% had surgery, 75% chemotherapy, 65% radiation therapy and 28% hormonal therapy. They were treated with hyperthermia in conjunction with radiation therapy (244 fields) or hyperthermia alone (5 fields). The hyperthermia treatment objectives were to elevate intratumoral temperatures to a minimum of 43.0 degrees C for 45 minutes while maintaining maximum normal tissue temperatures to less than or equal to 43 degrees C and maximum intratumoral temperatures to less than or equal to 50 degrees C. The hyperthermia was given within 30 to 60 minutes following radiation therapy without the administration of additional analgesics. Hyperthermia treatment regimens using radiative electromagnetic, ultrasound, or radiofrequency interstitial techniques were individualized, with 3 to 4 days between hyperthermia treatments and an average of 3.6 treatments (range 1-14; standard deviation 2.2) utilized per field. A total of 38 complications in 33 treatment fields were noted; an incidence of 27/198 (13.6%) for fields with superficially located tumors, and 6/51 (11.8%) in fields with more deeply located tumors. Univariate analyses demonstrated statistically significant correlations between the maximum tumor temperature (p = 0.0005), average of the maximum tumor temperatures (p = 0.0006), the average of the % tumor temperatures greater than 43.5 degrees C (p = 0.0071), and the average number of hyperthermia treatments (p = 0.033), with the development of complications. The average of the maximum measured tumor temperature for fields without complications was 44.6 degrees C compared with 45.9 degrees C for fields with complications. The complication rate increased from 7.5% (9/120) in fields that received one or two hyperthermia treatments to 18.6% (24/129) in fields that received greater than two hyperthermia treatments. Multivariate logistic regression analyses revealed the best bivariate model predictive of the development of complications included average of the maximum tumor temperature and the number of treatments per field (p = 0.00012 for the bivariate model).(ABSTRACT TRUNCATED AT 400 WORDS)

Regional hyperthermia--assessment of tolerance to treatment

To assess the patient's tolerance and the complications of treatment associated with delivery of regional hyperthermia using APAS BSD equipment, the data on 30 patients who received regional hyperthermia at the Radiation Oncology Center, Washington University School of Medicine, St. Louis, Missouri, has been reviewed. Most patients presented with advanced or recurrent tumors not amenable to conventional treatment modalities. Hyperthermia was administered in combination with either radiotherapy or chemotherapy. Cardiovascular evaluation was a standard part of pre-treatment work-up. Temperatures were obtained through interstitial probes, catheters inserted into the body cavities and (to record core temperature) esophagus. Local discomfort, anxiety, systemic temperature elevation, and tachycardia were the predominant factors limiting the number of sessions, the duration of sessions and the deposition of power, in 18, 6, 3, and 2 patients, respectively. The complications of treatment were rare. Significant injuries of the superficial tissues were recorded in two patients in whom this could be attributed to contact of urine and stool with the skin surface. Neuropathy was observed in two patients, both of whom had pelvic masses adjacent to or invading into the affected nerves. Both patients had received pelvic irradiation. Neuropathy developed within several days after the first hyperthermia session and proved reversible within several months. No injuries of the visceral organs that could be clearly attributed to hyperthermia have been recorded.

Intraoperative interstitial hyperthermia in conjunction with intraoperative radiation therapy in a radiation-resistant carcinoma of the abdomen: report on the feasibility of a new technique

The application of a new technique of intraoperative interstitial hyperthermia (IOHT) and intraoperative radiation therapy (IORT) was investigated for unresectable abdominal carcinoma. A 43-year-old white male presented with severe back pain due to metastatic adenocarcinoma in the left paravertebral area, producing erosion of the body of T12. The disease had not responded to external beam radiation therapy. The tumor was approached through a thoraco-abdominal incision and IOHT was delivered via interstitial electrodes. Temperature was monitored at 16 locations within the tumor. An LCF hyperthermia unit was utilized to deliver RF power and produced a treatment temperature of 43 degrees C for 60 minutes uniformly throughout the treatment volume. Immediately following hyperthermia treatment, the lesion was treated with 15 meV electrons via IORT to a tumor dose of 25Gy. The patient recovered without complication and had complete relief from pain. Posttreatment CT scans have demonstrated control of disease over a 5-month follow-up period. A clinical pilot study has been established to further investigate the application of this combination therapy.

Localized deep microwave hyperthermia in the treatment of poor operative risk patients with benign prostatic hyperplasia

Non-invasive localized deep microwave hyperthermia was applied as an alternative treatment to surgery in 29 patients with contraindications for prostatectomy. Patients were treated twice weekly, on Mondays and Thursdays, for 1 hour, without sedation on an outpatient basis. All patients tolerated treatment well without secondary effects. The results indicate that localized deep microwave hyperthermia applied by this method is safe and effective in the treatment of benign prostatic hyperplasia.

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.

Design and thermometry of an intracavitary microwave applicator suitable for treatment of some vaginal and rectal cancers

The construction of a modified coaxial cable as an intracavitary microwave applicator suitable for use in some vaginal and rectal cancers is presented. Thermometry was performed for microwave frequencies of 300, 400, 650, and 915 MHz. Temperature profiles in tissue phantoms were obtained with non-perturbing temperature probes and thermography, and the data were compared with those obtained in dogs. The temperature profiles were dependent on the frequency of the microwaves and the insertion depth of the applicator. In addition, an acrylic cylindrical spacer external to the applicator also altered the heating pattern. Therefore, with proper combinations of frequency, insertion depth and spacer, the applicator can be used for heating tumors in some clinical situations.

Response to heat treatment (42.5 degrees C) in vivo and in vitro of five human melanoma xenografts

The response to heat (42.5 degrees C) of five human melanoma xenografts was studied. Tumours grown subcutaneously in the hind leg of athymic mice were heated in a water-bath and specific growth delay was used as a measure of response. In other experiments, cells from the same xenografts were heated in vitro and the colony-forming ability was assayed in soft agar. The slopes of the in-vivo dose-response curves (specific growth delay versus heating time) varied within a factor of about three among the five melanomas. The Do values of the in-vitro heat survival curves ranged from 44 +/- 3 to 123 +/- 15 min. The response to heat in vivo was not positively correlated with the tumour volume-doubling time, the growth fraction, the cell loss factor or the intrinsic heat sensitivity of the tumour cells, i.e., the Do values of the in vitro heat survival curves. If the results obtained in the present work are representative for clinical practice, they indicate that the response to heat may vary considerably among tumours in different patients. This variability can probably not be predicted from measurements of cytokinetic parameters of the tumours. The lack of correlation between the response to heat in vivo and in vitro demonstrates that extrapolations of results from studies in vitro to tumours are highly speculative and, when attempted, should be executed only with extreme caution.