Vaginal changes, sexual functioning and distress of women with locally advanced cervical cancer treated in the EMBRACE vaginal morbidity substudy

OBJECTIVE

The EMBRACE-vaginal morbidity substudy prospectively evaluated physician-assessed vaginal changes and patient-reported-outcomes (PRO) on vaginal and sexual functioning problems and distress in the first 2-years after image-guided radio(chemo)therapy and brachytherapy for locally advanced cervical cancer.

METHODS

Eligible patients had stage IB1-IIIB cervical cancer with ≤5 mm vaginal involvement. Assessment of vaginal changes was graded using CTCAE. PRO were assessed using validated Quality-of-Life and sexual questionnaires. Statistical analysis included Generalized-Linear-Mixed-Models and Spearman's rho-correlation coefficients.

RESULTS

113 eligible patients were included. Mostly mild (grade 1) vaginal changes were reported over time in about 20% (range 11-37%). At 2-years, 47% was not sexually active. Approximately 50% of the sexually active women reported any vaginal and sexual functioning problems and distress over time; more substantial vaginal and sexual problems and distress were reported by up to 14%, 20% and 8%, respectively. Physician-assessed vaginal changes and PRO sexual satisfaction differed significantly (p ≤ .05) between baseline and first follow-up, without further significant changes over time. No or only small associations between physician-assessed vaginal changes and PRO vaginal functioning problems and sexual distress were found.

CONCLUSIONS

Mild vaginal changes were reported after image-guided radio(chemo)therapy and brachytherapy, potentially due to the combination of tumors with limited vaginal involvement, EMBRACE-specific treatment optimization and rehabilitation recommendations. Although vaginal and sexual functioning problems and sexual distress were frequently reported, the rate of substantial problems and distress was low. The lack of association between vaginal changes, vaginal functioning problems and sexual distress shows that sexual functioning is more complex than vaginal morbidity alone.

Lichen Sclerosis is Associated With a High Rate of Local Failure After Radio(chemo)therapy for Vulvar Cancer

AIMS

Radio(chemo)therapy plays an important role in the treatment of vulvar cancer, either as postoperative treatment or as definitive treatment in patients who present with inoperable disease. Only limited data are available regarding outcome after modern state of the art radio(chemo)therapy and more information regarding prognostic factors are warranted. The aim of this study was to evaluate disease outcomes after radio(chemo)therapy in patients with vulvar cancer with special emphasis on the impact of lichen sclerosis on local control.

MATERIALS AND METHODS

All consecutive patients (n = 109) from the western half of Denmark who were treated with definitive (n = 52) or postoperative (n = 57) radio(chemo)therapy between January 2013 and January 2020 were included. Local control, cause-specific survival and overall survival, as well as morbidity, were analysed using Kaplan-Meier statistics. Prognostic factors for local control were analysed in univariate and multivariate analysis.

RESULTS

At a median follow-up of 35 (4-95) months, 46 (42.0%) patients were diagnosed with recurrence. Eighty per cent of the recurrences were located to the vulva region, leading to a 5-year local control of 58.9% (confidence interval 47.9-69.9). Cause-specific survival was 62.9% (confidence interval 53.1-72.7), whereas overall survival was 58.0% (confidence interval 47.6-68.5). Grade 3-4 morbidity was diagnosed in 10 (9%) patients. Lichen sclerosis (hazard ratio 3.89; confidence interval 1.93-7.79) was an independent risk factors for local recurrence. Patients without lichen sclerosis had a 5-year local control rate of 83.6% (confidence interval 67.2-99.0) and 62.6% (confidence interval 43.2-82.0) after postoperative and definitive radio(chemo)therapy, respectively. In patients with lichen sclerosis, the local control rate was 44.0% (confidence interval 19.3-69.0) and 17.6% (confidence interval 0-30.0) after postoperative and definitive radio(chemo)therapy, respectively.

CONCLUSION

Radio(chemo)therapy plays an important role in the treatment of vulvar cancer. However, despite dose escalation, a substantial proportion of patients experienced local relapse. Pre-existing lichen sclerosis seems to have a significant impact on the risk of recurrence. This should influence surveillance programmes for these patients.

Clinical and imaging findings in cervical cancer and their impact on FIGO and TNM staging - An analysis from the EMBRACE study

OBJECTIVE

To investigate differences in local tumour staging between clinical examination and MRI and differences between FIGO 2009, FIGO 2018 and TNM in patients with primary cervical cancer undergoing definitive radio-chemotherapy.

METHODS

Patients from the prospective observational multi-centre study "EMBRACE" were considered for analysis. All patients had gynaecological examination and pelvic MRI before treatment. Nodal status was assessed by MRI, CT, PET-CT or lymphadenectomy. For this analysis, patients were restaged according to the FIGO 2009, FIGO 2018 and TNM staging system. The local tumour stage was evaluated for MRI and clinical examination separately. Descriptive statistics were used to compare local tumour stages and different staging systems.

RESULTS

Data was available from 1338 patients. For local tumour staging, differences between MRI and clinical examination were found in 364 patients (27.2%). Affected lymph nodes were detected in 52%. The two most frequent stages with FIGO 2009 are IIB (54%) and IIIB (16%), with FIGO 2018 IIIC1 (43%) and IIB (27%) and with TNM T2b N0 M0 (27%) and T2b N1 M0 (23%) in this cohort.

CONCLUSIONS

MRI and clinical examination resulted in a different local tumour staging in approximately one quarter of patients. Comprehensive knowledge of the differential value of clinical examination and MRI is necessary to define one final local stage, especially when a decision about treatment options is to be taken. The use of FIGO 2009, FIGO 2018 and TNM staging system leads to differences in stage distributions complicating comparability of treatment results. TNM provides the most differentiated stage allocation.

Urinary and sexual dysfunction in women after resection with and without preoperative radiotherapy for rectal cancer: a population-based cross-sectional study

AIM

Knowledge of urinary and sexual dysfunction in women after rectal cancer treatment is limited. This study addresses this in relation to the use of preoperative radiotherapy, type of surgery and the presence of bowel dysfunction.

METHOD

All living female patients who underwent abdominoperineal excision (APE) or low anterior resection (LAR) for rectal cancer in Denmark between 2001 and 2007 were identified. Validated questionnaires (the ICIQ-FLUTS and the SVQ) on urinary and sexual function were completed by 516 (75%) and 482 (72%) recurrence-free patients in 2009.

RESULTS

Urgency and incontinence were reported by 77 and 63% of respondents, respectively. Vaginal dryness, dyspareunia and reduced vaginal dimensions occurred in 72, 53 and 29%, respectively, and 69% reported that they had little/no sexual desire. Preoperative radiotherapy was associated with voiding difficulties (OR = 1.63, 95% CI 1.09-2.44), reduced vaginal dimensions (OR = 4.77, 95% CI 1.97-11.55), dyspareunia (OR = 2.76, 95% CI 1.12-6.79), lack of desire (OR = 2.22, 95% CI 1.09-4.53) and reduced sexual activity (OR = 0.55, 95% CI 0.30-0.98). Patients undergoing APE had a higher risk of dyspareunia (OR = 2.61, 95% CI 1.00-6.85). Bowel dysfunction after LAR was associated with bladder storage difficulties (OR = 1.64, 95% CI 1.01-2.65), symptoms of incontinence (OR = 2.17, 95% CI 1.35-3.50), lack of sexual desire (OR = 2.69, 95% CI 1.21-5.98), sexual inactivity (OR = 0.48, 95% CI 0.24-0.96) and sexual dissatisfaction (OR = 0.40, 95% CI 0.20-0.82).

CONCLUSION

Urinary and sexual problems are common in women after treatment for rectal cancer. Preoperative radiotherapy interferes with several aspects of urinary and sexual functioning. Bowel dysfunction after LAR is associated with urinary dysfunction and a reduction in sexual desire, activity and satisfaction.

A 10-year experience of total pelvic exenteration for primary advanced and locally recurrent rectal cancer based on a prospective database

AIM

The study was conducted in a dedicated centre treating the majority of Danish patients with intended curative total pelvic exenteration for primary advanced (PARC) or locally recurrent (LRRC) rectal cancer. We compared PARC and LRRC and analysed postoperative morbidity and mortality, and long-term outcome.

METHOD

There were 90 consecutive patients (PARC/LRRC 50/40) treated between January 2001 and October 2010, recorded on a prospectively maintained database.

RESULTS

The median age was 63 (32-75) years with a gender ratio of 7 women to 83 men. All patients were American Society of Anesthesiologists level I or II. Sacral resection was performed in five patients with PARC and 15 with LRRC (P=0.002). R0 resection was achieved in 33 (66%) patients with PARC and in 15 (38%) with LRRC, R1 resection in 17 (34%) with PARC and 20 (50%) with LRRC and R2 resection in five (13%) with LRRC. R0 resection was more frequent in PARC (P=0.007). Forty-four (49%) patients had no postoperative complications. Fifty-five major complications were registered. Two (2.2%) patients died within 30 days, and the total in-hospital mortality was 5.6%. The median follow-up was 12 (0.4-91) months. The 5-year survival was 46% for PARC and 17% for LRRC (P=0.16).

CONCLUSION

Pelvic exenteration is associated with considerable morbidity but low mortality in an experienced centre. Pelvic exenteration can improve long-term survival, especially for patients with PARC. However, pelvic exenteration is also justified for patients with LRRC.

A national cohort study of long-course preoperative radiotherapy in primary fixed rectal cancer in Denmark

OBJECTIVE

Preoperative radiotherapy has been shown to enable a fixed rectal cancer to become resectable which in turn may result in long-time survival. In this study, we analysed the outcome of long-course preoperative radiotherapy in fixed rectal cancer in a national cohort including all Danish patients registered with primary inoperable rectal cancer and treated in the period May 2001 to December 2005.

METHOD

The study was based on surgical and demographic data from a continuously updated and validated national database. In addition, retrospective data were retrieved from all departments of radiotherapy concerning technique of radiotherapy, dose and fractionation and use of concomitant chemotherapy. Outcome was determined by actuarial analysis of local control, disease-free survival and overall survival.

RESULTS

A total of 258 patients with fixed rectal cancer received long-course radiotherapy (> 45 Gy). The median age at diagnosis was 66 years (range: 32-85) and 185 (72%) patients were male. The resectability rate was 80%, and a R0 resection was obtained in 148 patients (57% of all patients and 61% of those operated). The 5-year local recurrence rate for all patients was 5% (95% CI: 3-7%), and the actuarial distant recurrence rate was 41% (95% CI: 35-47%). The cumulative 5-year disease-free survival was 27% (95% CI: 22-32%) and overall 5-year survival was 34% (95% CI: 29-39%).

CONCLUSIONS

This study is the first population-based report on outcome of preoperative long-course radiotherapy in a large unselected patient group with clinically fixed rectal cancer. Most patients could be resected with the intention of cure and one in three was alive after 5 years.

Clinical outcome in 520 consecutive Danish rectal cancer patients treated with short course preoperative radiotherapy

AIM

The purpose of this study was to analyse the results of preoperative short course radiotherapy in a consecutive, national cohort of patients with rectal cancer.

METHODS

Through a validated, prospective national database we identified 520 Danish patients who presented with high-risk mobile tumours in the lower two thirds of the rectum and were referred for preoperative radiotherapy with 5 x 5 Gy. The inclusion period was 56 months. Radiotherapy data was retrospectively collected.

RESULTS

Of the 520 patients, 514 completed radiotherapy and 506 had surgery. Surgery was considered curative in 439 patients. The 3-year local recurrence rate was 4.0% (95% CI 2.5-6.5%) and the distant recurrence rate at 3 years was 18.7% (95% CI 15.4-22.5%). The 5-year disease free survival rate was 40.2% (95% CI 27.0-53.1%) and overall survival 50.4% (95% CI 36.1-63.1%). Most tumours (61%) were classified as T3 or T4 and 41% of the local recurrences occurred in patients with a fixed tumour at surgery.

CONCLUSION

This study confirms data from randomised studies that the short course 5 x 5 Gy regime is a feasible treatment for locally advanced rectal cancer even when applied in a population outside clinical trials.

Perineal healing and survival after anal cancer salvage surgery: 10-year experience with primary perineal reconstruction using the vertical rectus abdominis myocutaneous (VRAM) flap

Salvage surgery of recurrent or persistent anal cancer following radiotherapy is often followed by perineal wound complications. We examined survival and perineal wound complications in anal cancer salvage surgery during a 10-year period with primary perineal reconstruction predominantly performed using vertical rectus abdominis myocutaneous (VRAM) flap. Between 1997 and 2006, 49 patients underwent anal cancer salvage surgery. Of these, 48 had primary reconstruction with VRAM. Overall survival was computed by the Kaplan-Meier method and mortality rate ratios (MRRs) by Cox regression. One patient (2%) died within 30 days postoperatively. Postoperative complications necessitated reoperation in eight (16%) patients. We found no major perineal wound infections. Major perineal wound breakdown occurred in the only patient in whom VRAM was not used. Five-year survival was 61% [95% confidence interval (CI) 43-75%]. Free resection margins (R0) were obtained in 78% of patients, with 5-year survival of 75% (95% CI 53-87%). Involved margins, microscopically only (R1) or macroscopically (R2), strongly predicted an adverse outcome [age-adjusted 2-year MRRs (95% CI) R1 vs. R0 = 4.1 (0.7-23.6), R2 vs. R0 = 10.9 (2.2-54.2)]. We conclude that anal cancer salvage surgery can yield long-time survival but obtaining free margins is critical. A low rate of perineal complications is achievable by primary perineal reconstruction using VRAM flap.

Invasive oxygen measurements and pimonidazole labeling in human cervix carcinoma

PURPOSE

This study was designed to compare tumor hypoxia assessed by invasive O2 sensitive electrodes and pimonidazole labeling in primary human cervix carcinomas.

METHODS AND MATERIALS

Twenty-eight patients with primary cervix carcinomas (FIGO Stage Ib-IVa) were investigated. Both invasive pO2 measurements and pimonidazole labeling were obtained in all patients. Before treatment, patients were given pimonidazole as a single injection (0.5 g/m2 i.v.). Ten to 24 h later, oxygenation measurements were done by Eppendorf histography, and after this procedure biopsies were taken for pimonidazole-binding analysis. Tumor oxygen partial pressure (pO2) was evaluated as the median tumor pO2 and the fraction of pO2 values < or = 10 mmHg (HF10). Biopsies were formalin fixed and paraffin embedded, and hypoxia was detected by immunohistochemistry using monoclonal antibodies directed against reductively activated pimonidazole. Pimonidazole binding was evaluated by a semiquantitative scoring system.

RESULTS

Both Eppendorf measurements and pimonidazole binding showed large intra-and intertumor variability. A comparison between pimonidazole binding expressed as the fraction of fields at the highest score and HF10 showed a trend for the most well-oxygenated tumors having a low fraction of fields; however, the correlation did not reach statistical significance (p = 0.43, r = 0.165; Spearman's rank correlation test).

CONCLUSION

Hypoxia measured in human uterine cervix carcinomas is heterogeneously expressed both within and between tumors when assessed by either invasive pO2 measurements or pimonidazole binding. Despite a trend that tumors with high pO2 values expressed less pimonidazole binding, no correlation was seen between the two assays in this preliminary report.

Has the outlook improved for amifostine as a clinical radioprotector?

Amifostine has recently been approved for clinical radiotherapy as a protector against irradiation-induced xerostomia. It is our aim to review the outlook for using amifostine as a general clinical radioprotector. Protection against X-rays is mainly obtained by the scavenging of free radicals. The degree of protection is therefore highly dependent on oxygen tension, with protection factors ranging from 1 to 3. Maximal protection is observed at physiological levels of oxygenation. A great variability in protection has also been observed between different normal tissues. Some tissue, like brain, is not protected while salivary glands and bone marrow may exhibit a three-fold increase in radiation tolerance. Amifostine is dephosphorylized to its active metabolite by a process involving alkaline phosphatase. Due to lower levels of alkaline phosphatase in tumor vessels, amifostine is marketed as a selective protector of normal tissue and not tumors. However, the preclinical investigations concerning the selectivity of amifostine are controversial and the clinical studies are sparse and do not have the power to evaluate the influence of amifostine on the therapeutic index.

CONCLUSION

based on the present knowledge amifostine should only be used in experimental protocols and not in routine practice.

Radiotherapy in the management of cervical cancer in elderly patients

PURPOSE

To report treatment results and complications experienced by elderly patients treated with curatively intended radiotherapy for cancer of the uterine cervix.

PATIENTS AND METHODS

One hundred and fourteen elderly patients (median 75.5 years, range 70.0-85.9) consecutively referred for curative radiotherapy in the period 1987-1996 were prospectively followed with regard to tumour control and complications. The importance of age, stage (FIGO), tumour size, histology, tumour fixation, haemoglobin, concurrent disease, performance status (WHO) and type of radiotherapy were assessed using univariate and multivariate analyses.

RESULTS

Treatment was completed as planned in 68%, delayed in 29% and stopped prematurely in 3%. The frequency of grade 3 late complications was 11% and the actuarial probability at 5 years was 20%. Overall 5-year survival according to FIGO was 61% (I), 34% (II) and 25% (III). Cox multivariate analysis identified tumour size as independent prognostic factor for tumour control, disease-free survival and overall survival. FIGO stage was predictive for late grade 2 complications. We were unable to identify significant factors with respect to grade 3 complications. Age was not a significant parameter for any of the investigated endpoints.

CONCLUSION

Elderly patients in good performance status with advanced cancer of the uterine may tolerate radical radiotherapy with acceptable morbidity and reasonable survival. Radiotherapy may also be a good alternative in early stage disease for surgically unfit elderly patients.

Epidermal growth factor and acute radiation damage in CDF1 mice in vivo

The aim was to investigate if extent and time course of acute radiation damage to epidermis and intestine could be moderated by epidermal growth factor (EGF). Twelve-to-sixteen weeks old female CDF1 mice were treated either by single dose local irradiation to the right hind leg or total body irradiation (TBI). The endpoints were skin score and lethality, respectively. Human recombinant EGF was given s.c. or i.p. at a dose of 5-10 microg/day either before or after irradiation. Body weight was significantly higher for EGF treated animals compared with controls treated with saline. However, EGF did not reduce the median skin score following local irradiation and did not increase LD50 (days 1-6) following TBI. Further studies using more specific assays are necessary to determine if radiation damage to less toxic levels can be ameliorated by EGF.

A retrospective analysis of 82 cases of cancer of the penis

OBJECTIVE

To identify prognostic factors for penile cancer and to evaluate the treatment strategy for early-stage disease, proposed recently by the European Board of Urology (EBU).

PATIENT AND METHODS

The records of 82 patients consecutively referred to the uro-oncological centre at Aarhus University Hospital between 1965 and 1993 were reviewed. The importance of tumour stage, differentiation, patient age, local control and regional lymph node control were assessed using univariate and multivariate analyses.

RESULTS

Cox multivariate analysis identified differentiation (odds ratio [OR] = 6.04), UJCC-1978 T-stage (OR = 1.88) and age (OR = 1.04) as independent prognostic variables for survival. Penile amputation in tumours < 4 cm in diameter improved local control but not survival. Regional control and survival were not significantly improved by prophylactic adenectomy.

CONCLUSION

Differentiation, T-stage and age were prognostic factors for survival. The results support the EBU treatment strategy involving penis-conserving therapy and watchful waiting for early-stage disease.

Is there a radiobiologic basis for improving the treatment of advanced stage cervical cancer?

The success of radiotherapy in eradicating the primary tumor in patients with locally advanced cervical cancer is limited by normal tissue tolerance. Systematic recording of morbidity and treatment parameters is therefore very important for radiobiologic treatment optimization and clinical decision making. There is substantial evidence that fractionation schedules employing large doses per fraction lead to a loss of therapeutic ratio. A similar argument could be used for high-dose-rate (HDR) brachytherapy that should also be administered in small dose fractions. However, HDR brachytherapy might convey some advantage to physical dose distribution that should be weighed against the radiobiologic advantages of low-dose-rate (LDR) continuous irradiation. Increasing overall treatment time reduces local control probability, whereas a shorter overall treatment time by accelerated fractionation may improve the therapeutic ratio, at least in fast-growing tumors. Hypoxia and reduced oxygen delivery are associated with poor radiation response. Anemia should be compensated, if necessary. The role of hypoxic modification needs to be further explored. In the future, the therapeutic ratio may also be improved by the use of chemical and biologic response modifiers. Tumors are heterogeneous with respect to intrinsic radiosensitivity, proliferation parameters, and extent of hypoxia. Until a detailed prognostic profile can be obtained for each patient, optimal curative radiotherapy must aim for a sufficient dose, short overall treatment time, hypoxic modification, and LDR or low dose per fraction.

[Treatment of penile cancer]

In Denmark about 40 new cases of cancer of the penis are diagnosed each year. Several studies have retrospectively investigated the treatment results in this rare disease. However, most of these studies include few patients and are difficult to compare because several classification systems have been used. Treatment of the primary tumour consists of local excision, laser surgery, partial/total penectomy or irradiation. The prognosis for early stage disease is apparently independent of the mode of treatment and the specific five-year survival rate is 80-90%. Several centres advise prophylactic treatment of the groin in node negative patients, claiming that the survival thereby is increased. However, the morbidity is considerable and randomized studies are not available. The treatment for metastatic inguinal nodes consists of adenectomy or irradiation. The specific five-year survival rate is 40-50%. Chemotherapy has been used for advanced disease. The response rates are low and the responses are of short duration.

Effects of step-down and step-up heating on the development of thermotolerance in a C3H mammary carcinoma in vivo

The effects of step-down (SDH) and step-up heating (SUH) on the development of thermotolerance were investigated in a C3H mammary carcinoma in vivo. The endpoint was tumour growth time, i.e. the time for a tumour to reach a volume five times that of the first treatment day. SDH consisted of 44.5 degrees C/5 min followed immediately by 41.0 degrees C/120 min. SUH consisted of the same heat treatments but in reverse sequence. Thermotolerance was detected by subsequent heating at 43.5 degrees C at variable intervals following the primary SDH or SUH. The degree of thermotolerance was quantified by the thermotolerance ratio (TTR) calculated as a ratio between the slope of the dose-response curve for tumours heated at 43.5 degrees C and tumours preheated with either SDH or SUH followed by 43.5 degrees C. Both SDH and SUH induced thermotolerance. However, the maximal degree of thermotolerance and the time interval to reach maximum thermotolerance were different. For SUH maximal thermotolerance was observed at 8 h with a TTR of 3.6. For SUH, thermotolerance peaked at 24-28 h with a TTR of 7.3. In both cases thermotolerance had decayed with a 120 h interval. The SDH priming induced about 2.5 times more heat damage than SUH. The results are therefore in agreement with previous data obtained in the same tumour model by single heating showing that both the degree and the time to reach maximal thermotolerance increases with pretreatment heat damage. In addition, the results indicate that thermotolerance and thermosensitization are independent phenomena.

Deep heating using a movable applicator phased array hyperthermia system. A preclinical feasibility study

A preclinical evaluation of the 'movable applicator phased array hyperthermia system' was performed. The system employs four coherent applicators enabling power steering by amplitude and phase control. This concept has already been used in other systems, but the combination with a compact applicator design and easy movement of applicators has not been used before. The paper contains a description of the system and a verification of its performance using quality assurance tests with scanned E-field measurements. A clinical simulation was performed in pig to address the clinical feasibility of the system. The target volume was the left kidney. Two heating sessions, with and without occluded blood-flow to the kidney, were performed. In the low-flow experiments a temperature of 48 degrees C and 46 degrees C was obtained in the upper and lower pole of the kidney respectively. For the high-flow experiment the temperature in the upper pole was 48 degrees C.

Use of tetrahydraindazolone dicarboxylic acid (HIDA) to improve the therapeutic effect in vivo of combined cisplatin, heat and radiation treatment

The effect of tetrahydraindazolone dicarboxylic acid (HIDA) on tumour response and mouse lethality after treatment with cisplatin given either alone or combined with hyperthermia (43.5 degrees C/60 min) with or without radiation, was studied in the CDF1 mouse bearing a foot transplanted C3H mouse mammary carcinoma. The tumour response to a combined heat, cisplatin and HIDA treatment was assessed by tumour growth time, while local tumour control was used when irradiation was added to that treatment scheme. Toxicity was estimated as lethality within 14 days. Cisplatin and heat exerted the highest antitumour effect when given simultaneously, but at the same time there was a substantial increase in lethality. No sensitization of the tumour response or enhanced toxicity to cisplatin was observed if heat was given sequentially (i.e. 4 h) after cisplatin. The effect of this sequential schedule being only additive. When HIDA (100 mg/kg) was given 150 min before cisplatin and tumours heated 15 min later, the lethal toxicity was significantly reduced. HIDA did not, however, influence tumour growth time results. In tumour control studies combining radiation, drug and heat, cisplatin (6 mg/kg) and heat (43.5 degrees C/60 min) were given simultaneously 4 h after local irradiating the leg of tumour-bearing mice. The lethality of this regime was more than 55%, but when HIDA was added to the protocol, the toxicity fell to 5% without affecting local tumour control. In conclusion, HIDA administered before cisplatin protects against drug-induced toxicity without reducing the drug's antitumour activity when used alone or in combination with hyperthermia and/or radiation, and thus results in a significantly improved therapeutic benefit.

A mathematical model for cell killing by heat applied to a C3H mammary carcinoma in vivo

Jung (1986) has proposed a mathematical model for cell killing by hyperthermia which assumes that heat killing involves two steps: the production (p) of non-lethal lesions at random and a subsequent conversion (c) into lethal lesions. The p & c model has been shown to predict the survival of CHO cells heated in vitro even when complicated biological phenomena such as thermotolerance and step-down heating (SDH) are involved (Jung 1986, 1991). In the present study the objective was to test the p & c model's ability to describe the effect of single heating and SDH in an experimental tumour in vivo. The endpoint was tumour growth delay (GD). The doubling times (DT) for untreated and heated tumours were similar, and the surviving fraction (SF) could therefore be estimated using: SF = -in(2).GD/DT. SF was fitted to the model by non-linear regression. The p & c model adequately described the GD obtained by SDH (39-44.5 degrees C) and single heating above 42.5 degrees C. Multiple linear regression showed that the residuals for single heating and SDH were independent of both heating time and temperature. However, the residuals for single heating (41-44.5 degrees C) were significantly correlated to heating time when analysed separately. The GD obtained by the use of extended single heating times at or below 42.5 degrees C was therefore overestimated by the model. Development of chronic thermotolerance during heating may account for the observed divergence. The Arrhenius plots for both p and c were log-linear with activation energies of 678 and 311 kJ/mol, respectively. Jung (1986) has previously reported similar p and c activation energies above 42.5 degrees C for CHO cells in vitro.

Winner of the Lund Science Award 1992. Thermosensitization induced by step-down heating. A review on heat-induced sensitization to hyperthermia alone or hyperthermia combined with radiation

A few minute's exposure to a high temperature (sensitizing treatment, ST) may substantially increase the cytotoxic and the radiosensitizing effect of a subsequent heating at a lower temperature (test treatment, TT). This phenomenon, which is known as step-down heating (SDH) or thermosensitization, has been observed both in cultured cells in vitro and in tumours and normal tissues in vivo. The effect of SDH increases with a lowering of TT temperature, but it is rapidly lost at temperatures very close to 37 degrees C. SDH-induced thermosensitization decays within a few hours, when an interval is inserted between ST and TT. In vitro results suggest an exponential decay of the SDH effect with half times ranging from 1.5- to 3.1 h. The effect of SDH increases with increasing ST time or temperature. For single heating, the Arrhenius plot is biphasic with activation energies of 500-800 and 1200-1700 kJ/mol above and below a break point temperature in the region 42.5-43.0 degrees C, respectively. For SDH, the Arrhenius plot gradually becomes monophasic with increasing severity of ST and it approaches asymptotically to an activation energy of about 400 kJ/mol. The reduction of the activation energy depends on cell survival after the priming ST and not on the specific ST heating time or temperature. SDH strongly enhances hyperthermic radiosensitization with a 5-6-fold reduction of the radiation dose required to achieve tumour control. The thermosensitizing and the radiosensitizing effects of SDH have several features in common. Both effects become more prominent when the TT temperature is decreased and when the ST heating time or temperature increases. In addition, the decay kinetics for both effects are comparable. For heat alone, the effect of SDH in tumour and normal tissue seems to be quantitatively similar. However, the therapeutic ratio may be increased by combining SDH with radiation. Biologically, the critical subcellular targets involved in the SDH effect have not been revealed. However, the ability of SDH to inhibit the clearance of heat-induced aggregation of proteins in the nucleus is interesting. Blockage of the nuclear function by proteins is a central theory in the present molecular biological models for both cell kill by heat and heat radiosensitization. Clinically, SDH may be an advantage since even a short exposure to high temperature increases the effect of an otherwise inadequate heat treatment. The disadvantages are that SDH complicates thermal dose calculations, and may cause unacceptable damage to normal tissue.

Cisplatin and hyperthermia treatment of a C3H mammary carcinoma in vivo. Importance of sequence, interval, drug dose, and temperature

The effect of combining cisplatin and hyperthermia was investigated in a C3H mammary carcinoma in vivo, using a regrowth delay assay. Cisplatin (6 mg/kg) was given i.p. at intervals ranging from 24 h before to 24 h after a 43.5 degrees C/60 min treatment. A supra-additive effect was obtained by giving cisplatin 15 min before heat, whereas an additive effect was obtained at all other intervals. The importance of cisplatin dose and heating temperature were investigated by giving variable cisplatin doses (2-8 mg/kg) 4 h or 15 min before a 60 min heating at temperatures in the range 40.5-43.5 degrees C. Linear relationships between length of regrowth delay and cisplatin dose were obtained both for cisplatin alone and for the combined treatment. The effect of the combined treatment could therefore be quantitated by a ratio (ER) between the slopes of dose-response curves. The ER values for cisplatin give 4 h before a 60 min heating at 42.5 or 43.5 degrees C were not significantly different from 1 (p greater than 0.5). In contrast, significant ER values were obtained above 40.5 degrees C (p less than 0.05) for cisplatin given 15 min before heat. The data demonstrates the possibility of achieving chemosensitization at clinically relevant temperatures.

Effect of step-down heating on the interaction between heat and radiation in a C3H mammary carcinoma in vivo

The effect of step-down heating (SDH) on the interaction between heat and radiation was investigated in a C3H mammary carcinoma in vivo. SDH consisted of an initial sensitizing treatment (ST) performed at 44.5 degrees C or 43.5 degrees C followed by a lower temperature test treatment (TT) in the range 41.0-43.0 degrees C. Step-up heating (SUH), i.e. TT followed by ST, and single heating were used as controls. The end-point was the radiation dose needed to control 50% of the tumours (TCD50). The results were evaluated by calculating the thermal enhancement ratio (TER) defined as TER = TCD50 (radiation alone)/TCD50 (radiation and heat). For a simultaneous application of TT and radiation a significant enhancement of direct heat radiosensitization was observed with increasing ST time or ST temperature using SDH. In contrast, only a minor increase was seen with SUH. A comparison between TCD50 values for the corresponding SUH and SDH schedules revealed that the SDH effect was largest at 41.0-42.0 degrees C and decreased with increasing TT temperature. The radiosensitizing effect of SDH also decreased if an interval was allowed between ST and TT or between TT and radiation. However, as a result of an increased cytotoxicity towards hypoxic tumour cells, the TCD50 value for SDH remained significantly smaller than for SUH, even with a sequential combination of radiation and heat.

Sensitization to hyperthermia induced in a normal tissue by step-down heating

The effect of step-down heating was investigated in the skin of the CDF1 mouse foot. Step-down heating was induced with a 44.7 degrees C/10 min pretreatment followed by a test treatment at a lower temperature for variable time. Step-up heating, that is, a test treatment followed by a 44.7 degrees C/10 min treatment, and single heating were used as controls. The normal tissue reaction was scored at five levels of damage (from slight redness and oedema to loss of a toe or greater reaction), and the heating time to induce each level in 50% of the animals, RD50, was used as the endpoint. The effect of step-down heating was quantified by the step-down ratio, calculated as the ratio of test heating times to obtain the endpoint. A significant reduction of the RD50 was seen at all score levels when the 44.7 degrees C/10 min was given in a step-down heating schedule, and the effect increased with decreasing test treatment temperature. In contrast, the heat sensitivity was only marginally influenced by step-up heating. An analysis of the time-temperature relationship demonstrated a log-linear relationship between temperature and RD50 for single heating in the range 42.2-44.7 degrees C and for step-down heating in the range 41.7-44.7 degrees C. The curve for step-down heating showed a lesser slope indicating a decrease of the activation energy. The kinetics of the SDH effect were investigated by inserting an interval between a primary 44.7 degrees C/10 min treatment and a test treatment performed at 42.2 degrees C. The effect of step-down heating was maximal with no interval between the priming treatment and the test treatment. As the interval was increased to 1.5 hr the step-down sensitization disappeared, and with even longer intervals thermotolerance developed. From a clinical point of view, the present data indicate that step-down heating may increase the extent of both reversible and irreversible heat damage in the normal tissue.

A comparison between the effect of step-down heating in a tumour and a normal tissue in vivo

A comparison between the effect of step-down heating (SDH) obtained in a C3H mammary carcinoma grown in the feet of CDF1 mice and the skin of normal CDF1 feet is presented. Water-bath heating was used, and SDH was obtained by giving a 44.7 degrees C/10 min treatment followed by heating at 42.2 degrees C for variable times. Single heating at 42.2 degrees C and step-up heating (SUH), i.e. 42.2 degrees C followed by 44.7 degrees C/10 min, were used as controls. The endpoint was the heating time at 42.2 degrees C to obtain either a definite tumour growth time (TGT50) or a specific skin score level (RD50) in 50% of the animals. The effect of SDH and SUH was quantified by the step-down ratio (SDR), calculated as the ratio of the heating times at 42.2 degrees C to obtain the specific endpoint. In both assays the effect of SDH was seen as a significant left shift of the SDH dose-response curve compared to the curve for single heating and SUH. For the comparison of the tumour and the normal tissue response, damage levels with comparable heating times for single heating were used. The therapeutic effect was then investigated by calculating the therapeutic gain factor (TGF), where TGF = SDR(tumour)/SDR(normal tissue). Neither SUH nor SDH gave a TGF significantly different from 1. The results suggest that SDH may be used clinically to shorten the heating time without decreasing the therapeutic effect.

The potential of using hyperthermia to eliminate radioresistant hypoxic cells

It is known that cells in a nutritionally deprived and acidic environment are sensitive to heat. In general these same cells are chronically hypoxic and therefore heat possesses the potential to eliminate (some) of this radioresistant population. A direct radiosensitization is observed when heat is given simultaneously with radiation. This effect occurs to the same extent in both aerobic and hypoxic cells, thus the oxygen enhancement ratio is unchanged. By giving heat several hours after radiation the direct radiosensitization is avoided and the specific heat killing of the acidic, chronically hypoxic, tumor cells may be utilized to improve the therapeutic gain. The current investigation clearly demonstrates this concept in a C3H mammary carcinoma using a local tumor control assay. This effect could be further enhanced by adding hypoxic radiosensitizers (nimorazole, misonidazole) or a blood flow modifier (nicotinamide) which can eliminate acutely hypoxic cells.

Step-down heating in a C3H mammary carcinoma in vivo: effects of varying the time and temperature of the sensitizing treatment

The effect of step-down heating (SDH), consisting of an initial sensitizing treatment (ST) performed at either 44.5 degrees C or 43.5 degrees C followed by a lower temperature test treatment (TT), was investigated in a C3H mammary carcinoma in vivo. A linear relationship between heating time and tumour growth delay was observed for all temperature combinations applied. At a given TT temperature, SDH increased the slope of the dose-response curve compared to the curve for tumours, single-heated without an initial ST. The slope of the SDH curves increased asymptotically towards a plateau value as the ST time at 44.5 degrees C was increased. The time-temperature relationship for single heating was described by a biphasic Arrhenius curve with activation energies of 1361 +/- 34 and 666 +/- 54 kJ/mol below and above an inflection point at 42.5 degrees C, respectively. For SDH, the Arrhenius curve gradually became straight with increasing ST time, and the activation energy saturated at a value of 425 +/- 25 kJ/mol. The reduction of the activation energy at an ST temperature of 43.5 degrees C was due rather to the extent of ST heat damage than to the ST time or temperature used. These results may be relevant for calculations of thermal doses, since even a short temperature peak (e.g. 44.5 degrees C/5 min) significantly changed the time-temperature relationship.

Time-temperature relationships for L1A2 cells step-down heated from 38 to 45 degrees C in vitro

The in vitro response of L1A2 cells to a single exposure to one temperature and to step-down heating was investigated. Single heating consisted of heating for a specified time at a constant temperature in the range 38.0-45.0 degrees C, whereas step-down heating involved a pretreatment of either 45.0 degrees C for 10 min or 42.0 degrees C for 90 min. The pretreatments were adjusted to give the same survival level. The survival curves for single heating had an initial shoulder followed by an exponential region, whereas for step-down heating they were strictly exponential and had no shoulder. The time-temperature relationship for cells exposed to single heating showed a biphasic Arrhenius curve with a downward inflection at 40.5 degrees C. Biphasic Arrhenius curves were also observed for step-down heating, but both the 45 degrees C/10 min and the 42 degrees C/90 min pretreatment showed an upward inflection that broke at 42.5 degrees C and 40.5 degrees C, respectively. The downward inflection on the Arrhenius curve for single heating has been attributed to thermotolerance development and the effect of step-down heating to a temporary inhibition of thermotolerance development. However, the present shape of the Arrhenius curves for step-down heating cannot be explained by inhibition of thermotolerance. It is therefore reasonable to assume that step-down heating is more than just the inhibition of thermotolerance, and that step-down heating and thermotolerance are distinct phenomena which act independently.

Thermotolerance in the mouse foot estimated at various levels of normal tissue damage

The effect of fractionated 43.7 degrees C water bath heating on the skin of CDF1 mice was investigated. The normal tissue damage was scored at five levels (from slight redness and oedema to loss of a toe or greater damage) according to an arbitrary score system. The heating time to induce a given level of damage in half of the treated animals (RD50) was used as an end point. The feet were exposed either to a single treatment at 43.7 degrees C for different time periods or to a priming treatment of 30 min. at 43.7 degrees C followed at different intervals by a second graded heat treatment at 43.7 degrees C. In all treatment schedules, the score level increased proportionally with heating time, and the score system offered a good description of the acute skin damage following hyperthermia. The priming heat treatment induced thermotolerance with a time course independent of the score level chosen to estimate the heat response. The thermotolerance developed rapidly, reached a maximum within a 24 hr. interval, and then decayed slowly. The degree of thermotolerance was calculated by means of two previously described formulas for the thermotolerance ratio (TTR). The kinetics of thermotolerance in the skin of mice was independent of the TTR formula, whereas the degree of thermotolerance depended on both the score level and the TTR formula used.

Effect of step-down heating on hyperthermic radiosensitization in an experimental tumor and a normal tissue in vivo

The effect of step-down heating (SDH) on the radiosensitization induced by simultaneous hyperthermia and radiation was investigated in a C3H mammary carcinoma inoculated into the feet of CDF1 mice and the skin of normal CDF1 feet. SDH consisted of a sensitizing treatment (ST) of 44.5 degrees C/10 min followed by a test treatment (TT) of 41.5 degrees C for 30, 60 or 120 min. Simultaneous administration of radiation and hyperthermia was achieved by delivering radiation in the middle of the TT. The endpoint selected was the radiation dose needed to achieve either tumor control or moist desquamation in 50% of the animals. The results were evaluated by the thermal enhancement ratio (TER), defined as dose of radiation needed to achieve endpoint in relation to dose of combined radiation and hyperthermia needed to achieve the endpoint. SDH of tumors increased the TER significantly compared with step-up heating (SUH). The ratios between TCD50 values for corresponding SDH and SUH increased with TT heating time and at 120 min a 2.5-fold increase in the radiosensitizing effect was achieved. It has previously been shown that SDH alone causes thermosensitization in tumors by decreasing the activation energy. However, the effect was too small to explain the increased radiosensitization observed with SDH. In the normal tissue studies SDH combined with radiation treatment gave a lower TER compared to the SDH tumor results, suggesting a possible therapeutic gain.

Factors of importance for the development of the step-down heating effect in a C3H mammary carcinoma in vivo

The effect of step-down heating (SDH) was investigated in a C3H mammary carcinoma inoculated into the feet of CDF1 mice. The SDH effect was evaluated by comparing slopes of time versus growth delay curves of SDH-heated with the curve for single-heated controls. The effect was quantified by a ratio: 'step-down ratio' (SDR), defined as slope (SDH-heated)/slope (single-heated). Step-down heating resulted in thermosensitization in contrast to step-up heating which did not affect the heat sensitivity. The kinetics of the step-down heating effect was investigated by inserting an interval between a 44.5 degrees C/10 min sensitizing treatment (ST) and a 42.0 degrees C test treatment (TT). The effect of SDH was maximal with no interval between ST and TT (SDR = 2.3), decayed within 2 h and turned into thermotolerance. This thermotolerance was maximal after 12 h and decayed within 120 h. The effect of varying the TT temperature was investigated in the range 39.0-44.5 degrees C (ST = 44.5 degrees C/10 min). Below 42.5 degrees C the SDR value increased exponentially, and even a 39 degrees C TT produced a significant heat damage. An Arrhenius analysis was made showing a straight line in the whole temperature range with an activation energy of 526 kJ/mol and an increased activation entropy. These data show that thermosensitization can be induced by SDH in C3H mammary carcinomas in vivo. The effect seems to decay within 2 h, and by decreasing the heat activation energies the effect of low temperature heating is increased.