Late effects of hyperfractionated radiotherapy for advanced head and neck cancer: long-term follow-up results of RTOG 83-13

Radiation ulcer treatment with hyperbaric oxygen therapy and haemoglobin spray: case report and literature review

OBJECTIVE

To explore the effectiveness of a combination of hyperbaric oxygen therapy and haemoglobin spray in radiation ulcer treatment.

METHOD

We reviewed the available literature and present a case report in which radiation ulcer was treated with a combination of hyperbaric oxygen therapy and haemoglobin spray.

RESULTS

After 30 sessions of hyperbaric oxygen therapy (2.4 ATA; 90 minutes each session) and administration of haemoglobin spray, the wounds showed gradual progress towards healing and a good granulating base was achieved. The wounds were closed after two months using a small split thickness skin graft.

CONCLUSION

A combination of hyperbaric oxygen therapy and haemoglobin spray was effective as a short course of treatment for radiation ulcers.

Dose-volume relationship for laryngeal substructures and aspiration in patients with locally advanced head-and-neck cancer

Background

Literature has shown a significant relationship between radiation dose to the larynx and swallowing disorders. We prospectively studied the dose-volume relationship for larynx substructures and aspiration.

Methods

Forty nine patients with stage III/IV head-and-neck (H&N) squamous cell carcinoma were prospectively enrolled in this IRB-approved, federally funded study. All patients received IMRT-based chemoradiation therapy (CRT) and were scheduled for videofluorography (VFG) prior to CRT and at 3, 6, 9, 12, and 24 months post-CRT. Twelve laryngeal substructures were contoured in each patient: thyroid cartilage, cricoid cartilage, total epiglottis, suprahyoid epiglottis, infrahyoid epiglottis, total larynx, supraglottic larynx, subglottic larynx, glottic larynx, arytenoids, aryepiglottic (AE) folds, and glossoepiglottic fold. After exclusions, 29 patients were included in the final analysis. Incidence of aspiration at 1 year following CRT was correlated with dose-volume data to laryngeal substructures using logistic regression.

Results

The median age was 54 years with 79% being non-smokers. Tumor sites included oropharynx (22), unknown primary (6), and hypopharynx (1). One year following CRT, 10/29 (34%) showed aspiration on VFG. Dose to the AE folds showed the highest correlation with aspiration at 12 months and was significant on multivariate analysis (p = 0.025). A mean dose cutpoint of 6500 cGy or higher to the AE folds was associated with an increased risk of aspiration at 1 year [positive likelihood ratio (+LR) 2.81, positive predictive value (PPV) 60%, negative predictive value (NPV) 92.9%, relative risk (RR) 8.4].

Conclusions

In this analysis, mean dose to the AE folds was associated with an increased risk of aspiration at 1 year. However, these are hypothesis-generating data that require further research and validation in a larger patient subset.

Late Local Treatment Morbidity after Accelerated Radiotherapy or Alternating Chemoradiotherapy for Advanced Head and Neck Carcinoma

Background

To report local long-term morbidity after concomitant boost radiotherapy (AFRT) or alternating chemoradiotherapy (CTRT), we analyzed the toxicity data recorded in 168 patients with advanced head and neck squamous cell carcinoma treated at our institution within phase II-III studies.

Patients and Methods

All patients enrolled in three consecutive phase II-III studies and followed for a minimum of three months after the end of treatment were included in the present analysis. Local late reactions were scored prospectively. The actuarial incidence of grade 2 or more (2-4) late local toxicity according to RTOG/EORTC was taken as endpoint. The median follow-up is 32.0 months (range, 3.3-138.1 months). For living patients the minimum and median follow-up are 12.1 and 69.3 months, respectively.

Results

The five-year actuarial incidence of grade 2+ and grade 3+ toxicity are 56.7 ± 5% and 21 ± 4%, respectively. At multivariate analysis, acute mucositis grade, complementary surgery, primary site and performance status proved to be independent predictive factors of grade 2+ late toxicity with P values of <0.001, 0.009, 0.022 and 0.033, respectively. No effect was found for treatment itself on the incidence of late toxicity, although patients treated with accelerated radiotherapy had a higher probability of confluent mucositis than patients treated with alternating chemoradiotherapy (68% vs 32%, P <0.01).

Conclusions

A substantial proportion of surviving patients develops late complications, although severe irreversible reactions occur in a minority of patients. Acute local toxicity can be used to predict local late toxicity that arises within five years of the end of treatment.

Nonstandard Fractionation Schedules in Radiation Therapy of Head and Neck Cancer: A Review

The authors present an updated review of the clinical trials on hyperfractionated and accelerated fractionation schedules in radiotherapy of head and neck cancer. The available results in terms of survival and local control, and acute and late toxicity data are summarized in order to show the current status of this research field. The new breed of fractionation schedules that are on study, designed on the ground of new rationales, are presented as well. Finally, an introductory overview of combination therapy including non standard fractionation radiotherapy associated with chemotherapy is reported70.

The synergistic effect of radiotherapy and immunotherapy: A promising but not simple partnership

Radiotherapy (RT) is one of the main components in the treatment of cancer. The better understanding of the immune mechanisms associated with tumor establishment and how RT affects inflammation and immunity has led to the development of novel treatment strategies. Several preclinical studies support the use of RT in combination with immunotherapy obtaining better local and systemic tumor control. Current ongoing studies will provide information about the optimal RT approach, but the development of reliable predictors of the response from the preclinical and the early phases of clinical studies is necessary to avoid discarding treatment strategies with significant clinical benefit. This review summarize the current concepts of the synergism between RT and immunotherapy, the molecular effects of RT in the tumor microenvironment, their impact on immune activation and its potential clinical applications in trials exploring this important therapeutic opportunity. Finally, the potential predictors of clinical response are discussed.

Modern Radiotherapy Concepts and the Impact of Radiation on Immune Activation

Even though there is extensive research carried out in radiation oncology, most of the clinical studies focus on the effects of radiation on the local tumor tissue and deal with normal tissue side effects. The influence of dose fractionation and timing particularly with regard to immune activation is not satisfactorily investigated so far. This review, therefore, summarizes current knowledge on concepts of modern radiotherapy (RT) and evaluates the potential of RT for immune activation. Focus is set on radiation-induced forms of tumor cell death and consecutively the immunogenicity of the tumor cells. The so-called non-targeted, abscopal effects can contribute to anti-tumor responses in a specific and systemic manner and possess the ability to target relapsing tumor cells as well as metastases. The impact of distinct RT concepts on immune activation is outlined and pre-clinical evidence and clinical observations on RT-induced immunity will be discussed. Knowledge on the radiosensitivity of immune cells as well as clinical evidence for enhanced immunity after RT will be considered. While stereotactic ablative body radiotherapy seem to have a beneficial outcome over classical RT fractionation in pre-clinical animal models, in vitro model systems suggest an advantage for classical fractionated RT for immune activation. Furthermore, the optimal approach may differ based on the tumor site and/or genetic signature. These facts highlight that clinical trials are urgently needed to identify whether high-dose RT is superior to induce anti-tumor immune responses compared to classical fractionated RT and in particular how the outcome is when RT is combined with immunotherapy in selected tumor entities.

Radiation plus Procarbazine, CCNU, and Vincristine in Low-Grade Glioma

BACKGROUND

Grade 2 gliomas occur most commonly in young adults and cause progressive neurologic deterioration and premature death. Early results of this trial showed that treatment with procarbazine, lomustine (also called CCNU), and vincristine after radiation therapy at the time of initial diagnosis resulted in longer progression-free survival, but not overall survival, than radiation therapy alone. We now report the long-term results.

METHODS

We included patients with grade 2 astrocytoma, oligoastrocytoma, or oligodendroglioma who were younger than 40 years of age and had undergone subtotal resection or biopsy or who were 40 years of age or older and had undergone biopsy or resection of any of the tumor. Patients were stratified according to age, histologic findings, Karnofsky performance-status score, and presence or absence of contrast enhancement on preoperative images. Patients were randomly assigned to radiation therapy alone or to radiation therapy followed by six cycles of combination chemotherapy.

RESULTS

A total of 251 eligible patients were enrolled from 1998 through 2002. The median follow-up was 11.9 years; 55% of the patients died. Patients who received radiation therapy plus chemotherapy had longer median overall survival than did those who received radiation therapy alone (13.3 vs. 7.8 years; hazard ratio for death, 0.59; P=0.003). The rate of progression-free survival at 10 years was 51% in the group that received radiation therapy plus chemotherapy versus 21% in the group that received radiation therapy alone; the corresponding rates of overall survival at 10 years were 60% and 40%. A Cox model identified receipt of radiation therapy plus chemotherapy and histologic findings of oligodendroglioma as favorable prognostic variables for both progression-free and overall survival.

CONCLUSIONS

In a cohort of patients with grade 2 glioma who were younger than 40 years of age and had undergone subtotal tumor resection or who were 40 years of age or older, progression-free survival and overall survival were longer among those who received combination chemotherapy in addition to radiation therapy than among those who received radiation therapy alone. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00003375.).

Final results of local-regional control and late toxicity of RTOG 9003: a randomized trial of altered fractionation radiation for locally advanced head and neck cancer

PURPOSE

To test whether altered radiation fractionation schemes (hyperfractionation [HFX], accelerated fractionation, continuous [AFX-C], and accelerated fractionation with split [AFX-S]) improved local-regional control (LRC) rates for patients with squamous cell cancers (SCC) of the head and neck when compared with standard fractionation (SFX) of 70 Gy.

METHODS AND MATERIALS

Patients with stage III or IV (or stage II base of tongue) SCC (n=1076) were randomized to 4 treatment arms: (1) SFX, 70 Gy/35 daily fractions/7 weeks; (2) HFX, 81.6 Gy/68 twice-daily fractions/7 weeks; (3) AFX-S, 67.2 Gy/42 fractions/6 weeks with a 2-week rest after 38.4 Gy; and (4) AFX-C, 72 Gy/42 fractions/6 weeks. The 3 experimental arms were to be compared with SFX.

RESULTS

With patients censored for LRC at 5 years, only the comparison of HFX with SFX was significantly different: HFX, hazard ratio (HR) 0.79 (95% confidence interval 0.62-1.00), P=.05; AFX-C, 0.82 (95% confidence interval 0.65-1.05), P=.11. With patients censored at 5 years, HFX improved overall survival (HR 0.81, P=.05). Prevalence of any grade 3, 4, or 5 toxicity at 5 years; any feeding tube use after 180 days; or feeding tube use at 1 year did not differ significantly when the experimental arms were compared with SFX. When 7-week treatments were compared with 6-week treatments, accelerated fractionation appeared to increase grade 3, 4 or 5 toxicity at 5 years (P=.06). When the worst toxicity per patient was considered by treatment only, the AFX-C arm seemed to trend worse than the SFX arm when grade 0-2 was compared with grade 3-5 toxicity (P=.09).

CONCLUSIONS

At 5 years, only HFX improved LRC and overall survival for patients with locally advanced SCC without increasing late toxicity.

Cancer Therapy: A Continuance of Health Burden

Background

Cancer diagnosis coupled with emotional impact converge to create one of the most difficult physical and emotional periods of life. Cancer treatment causes plethora of short and long term complications which can be so debilitating that patient may interrupt treatment. Pretreatment oral assessment and supportive oral care during and after cancer therapy can increase quality of life and supportive care costs.

Methods

Study was conducted on 189 patients (86: head and neck cancer cases, group I and 103: other than head and neck cancer cases, group II) receiving cancer therapy. Patients were subjected to clinical assessment and findings were recorded in specially designed proforma and complete oral (objective and subjective) and constitutional findings were recorded.

Results

Among the patients undergoing chemotherapy in both groups, prevalence of oral findings was found to be highest with methotrexate whereas constitutional symptoms was found to be highest with doxyrubicin. Whereas in radiotherapy patients subjective and objective oral symptoms increased from 10th - 30th fractionated dose of radiations and then subsequently decreased and constitutional symptoms were found to be consistent in all fractionated dosages with lowest at 50th fraction. Under combined chemo and radiotherapy patients, constitutional symptoms were highest than the oral findings.

Conclusions

Cancer therapy can greatly damage the normal tissues and diminish patients quality of life and often leads to serious clinical sequelae. Therefore, therapy induced damage should be anticipated and prevented whenever possible and managed early.

Radiobiological modeling of interplay between accelerated repopulation and altered fractionation schedules in head and neck cancer

Head and neck cancer represents a challenge for radiation oncologists due to accelerated repopulation of cancer cells during treatment. This study aims to simulate, using Monte Carlo methods, the response of a virtual head and neck tumor to both conventional and altered fractionation schedules in radiotherapy when accelerated repopulation is considered. Although clinical trials are indispensable for evaluation of novel therapeutic techniques, they are time-consuming processes which involve many complex and variable factors for success. Models can overcome some of the limitations encountered by trials as they are able to simulate in less complex environment tumor cell kinetics and dynamics, interaction processes between cells and ionizing radiation and their outcome. Conventional, hyperfractionated and accelerated treatment schedules have been implemented in a previously developed tumor growth model which also incorporates tumor repopulation during treatment. This study focuses on the influence of three main treatment-related parameters, dose per fraction, inter fraction interval and length of treatment gap and gap timing based on RTOG trial data on head and neck cancer, on tumor control. The model has shown that conventionally fractionated radiotherapy is not able to eradicate the stem population of the tumor. Therefore, new techniques such as hyperfractionated/ accelerated radiotherapy schedules should be employed. Furthermore, the correct selection of schedule-related parameters (dose per fraction, time between fractions, treatment gap scheduling) is crucial in overcoming accelerated repopulation. Modeling of treatment regimens and their input parameters can offer better understanding of the radiobiological interactions and also treatment outcome.

Interventions for the treatment of oral cavity and oropharyngeal cancer: radiotherapy

BACKGROUND

The management of advanced oral cavity and oropharyngeal cancers is problematic and has traditionally relied on surgery and radiotherapy, both of which are associated with substantial adverse effects. Radiotherapy has been in use since the 1950s and has traditionally been given as single daily doses. This method of dividing up the total dose, or fractionation, has been modified over the years and a variety of approaches have been developed with the aim of improving survival whilst maintaining acceptable toxicity.

OBJECTIVES

To determine which radiotherapy regimens for oral cavity and oropharyngeal cancers result in increased overall survival, disease free survival, progression free survival and locoregional control.

SEARCH STRATEGY

The following electronic databases were searched: the Cochrane Oral Health Group's Trials Register (to 28 July 2010), CENTRAL (The Cochrane Library 2010, Issue 3), MEDLINE via OVID (1950 to 28 July 2010) and EMBASE via OVID (1980 to 28 July 2010). There were no restrictions regarding language or date of publication.

SELECTION CRITERIA

Randomised controlled trials where more than 50% of participants had primary tumours of the oral cavity or oropharynx, and which compared two or more radiotherapy regimens, radiotherapy versus other treatment modality, or the addition of radiotherapy to other treatment modalities.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of risk of bias was undertaken independently by two or more authors. Study authors were contacted for additional information as required. Adverse events data were collected from published trials.

MAIN RESULTS

30 trials involving 6535 participants were included. Seventeen trials compared some form of altered fractionation (hyperfractionation/accelerated) radiotherapy with conventional radiotherapy; three trials compared different altered fractionation regimens; one trial compared timing of radiotherapy, five trials evaluated neutron therapy and four trials evaluated the addition of pre-operative radiotherapy. Pooling trials of any altered fractionation radiotherapy compared to a conventional schedule showed a statistically significant reduction in total mortality (hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.76 to 0.98). In addition, a statistically significant difference in favour of the altered fractionation was shown for the outcome of locoregional control (HR 0.79, 95% CI 0.70 to 0.89). No statistically significant difference was shown for disease free survival.No statistically significant difference was shown for any other comparison.

AUTHORS' CONCLUSIONS

Altered fractionation radiotherapy is associated with an improvement in overall survival and locoregional control in patients with oral cavity and oropharyngeal cancers. More accurate methods of reporting adverse events are needed in order to truly assess the clinical performance of different radiotherapy regimens.

Influence of interfraction interval on local tumor control in patients with limited-disease small-cell lung cancer treated with radiochemotherapy

PURPOSE

To investigate the influence of interfraction interval (IFI) on local recurrence-free survival (LRFS) in patients with limited-disease small-cell lung cancer (LD SCLC) treated with accelerated hyperfractionated radiotherapy (Acc Hfx RT) and concurrent cisplatin and etoposide (PE).

METHODS AND MATERIALS

A total of 103 patients were treated with either "early" (Cycle 1) or "late" (Cycle 4) concurrent Acc Hfx RT/PE. Two daily fractions were nonrandomly given using an IFI of either 4.5-5.0 h ("shorter") (n = 52) or 5.5-6.0 h ("longer") (n = 51).

RESULTS

The median LRFS and 5-year LRFS rate for all 103 patients were 52 months and 48%, respectively. Besides gender, Karnofsky performance status, and treatment group, IFI also influenced LRFS, whereas age and weight loss did not. When a multivariate model was used, IFI was marginally insignificant (p = 0.0770) as a predictor of LRFS. In terms of individual treatment groups, IFI was not significant in "early" Acc Hfx RT/PE but showed a strong trend in a "late" Acc Hfx RT/PE regimen. Although a shorter IFI led to a higher incidence of high-grade (>or=3) esophagitis, leukopenia, and infection, a correlation analysis of toxicities with all potential prognostic factors showed that a shorter IFI was not an independent predictor of any acute high-grade toxicity.

CONCLUSION

"Shorter" IFI had a marginally insignificant influence on LRFS. A strong trend favoring it was observed in patients treated with "late" concurrent Acc Hfx RT/PE. This may be of interest because it could contribute to further understanding of potential biologic parameters influencing treatment outcome.

Oral complications of radiotherapy

Radiotherapy-induced damage in the oral mucosa is the result of the deleterious effects of radiation, not only on the oral mucosa itself but also on the adjacent salivary glands, bone, dentition, and masticatory musculature and apparatus. Biological response modifiers, cytoprotective drugs, salivary-sparing radiation techniques, and surgery have been introduced to combat and, more importantly, to prevent, the development of these complications. Radiotherapy-induced oral complications are complex, dynamic pathobiological processes that lower the quality of life and predispose patients to serious clinical disorders. Here, we focus on these oral complications of radiotherapy, highlight preventive and therapeutic developments, and review the current treatment options available for these disorders.

Why to start the concomitant boost in accelerated radiotherapy for advanced laryngeal cancer in week 3

PURPOSE

We analyzed toxicity and the local control rates for advanced laryngeal cancer, treated with two accelerated fractionation schedules. The main difference between the schedules was the onset of the concomitant boost, in Week 3 or Week 4. Overall treatment time and total dose were equivalent.

METHODS AND MATERIALS

In a prospective, nonrandomized study of T3, T4, and advanced T2 laryngeal cancer, concomitant boost schedules were used in 100 patients. Thirty patients received a schedule of twice daily 1.2 Gy in Weeks 1-3, followed by twice daily 1.7 Gy in Weeks 4 and 5; total dose was 70 Gy (the hyperfractionated accelerated schedule [HAS] regimen). Seventy patients were treated with 5 times 2 Gy in Weeks 1 and 2, followed by daily 1.8 Gy and 1.5 Gy (boost) in Weeks 3-5; total dose 69.5 Gy (the accelerated schedule only [ASO] regimen). Distribution of T stage was 47%, 40%, and 12% for T2, T3, and T4, respectively. In 24% of the patients, lymph nodes were positive. Pretreatment tracheotomy or stridor or both occurred in 8 patients. The distribution of prognostic factors was not significantly different between the two fractionation schedules. Acute and late toxicity was assessed. Results were estimated by the use of actuarial methods. For late toxicity and local control univariate and multivariate analyses were performed. Tumor control probability analysis was used to model cure rate differences.

RESULTS

Overall acute mucositis score was equal for both schedules. Acute mucositis started and decreased significantly earlier in the HAS regimen. In all patients acute mucositis healed completely. The treatment was completed within 38 days in all patients. The regional control rate was 100% for clinical N0, and 75% for the clinical N+ patients. The 3-year local control rate was 59% and 78% for the HAS and ASO regimens, respectively (p = 0.05); the ultimate local control was 80% and 94%, respectively. In multivariate analysis, besides the fractionation schedule (relative risk [RR], 2.6 for HAS vs. ASO), pretreatment tracheotomy/stridor (RR 4.3, yes vs. no), and local tumor response 3-6 weeks after radiotherapy (RR 5.1, no vs. yes) were independent factors for local control. Tumor control probability analysis indicated that the onset of repopulation may be about 4-6 days earlier for the HAS regimen. The onset of repopulation in the HAS regimen is probably at the end of the second week or at the beginning of the third week. Severe late toxicity was observed in the HAS group and ASO group in, respectively, 11% and 16%. In multivariate analysis this toxicity related significantly to the field size and pretreatment tracheotomy/stridor.

CONCLUSIONS

In our study the timing of the boost in accelerated radiotherapy for advanced laryngeal cancer was an independent factor for local control, favoring the use of a concomitant boost in Week 3. This finding may indicate that accelerated repopulation of tumor cells starts early in the treatment phase.

Interfraction interval in patients with stage III non-small-cell lung cancer treated with hyperfractionated radiation therapy with or without concurrent chemotherapy: final results in 536 patients

We investigated the influence of interfraction interval (IFI) on treatment outcome in patients with stage III non-small-cell lung cancer (NSCLC) treated with hyperfractionated radiation therapy (Hfx RT) with or without concurrent chemotherapy (CHT). During 3 randomized phase III and 1 phase II study, a total of 536 patients were treated with Hfx RT alone or with concurrent carboplatin/etoposide. Two hundred eighty-five patients were treated with IFI of 4.5-5.0 hours, while 251 patients were treated with IFI of 5.5-6.0 hours. "Shorter" (4.5-5.0 hours) IFI led to better overall survival (OS) (P = 0.0000) and local recurrence-free survival (LRFS) (P = 0.0000). Multivariate analyses showed IFI to be an independent prognosticator of both OS and LRFS. These results were confirmed when we separated all patients (n = 536) into those treated with Hfx RT only (n = 127) and those treated with concurrent RT/CHT (n = 409). Various RT-related high-grade acute toxicity was not different between the 2 IFI, but patients treated with shorter IFI had a significantly higher incidence of hematological toxicity (P = 0.002). None of the late high-grade toxicities were different between the 2 interfraction intervals. Using regression analysis, it was shown that IFI was not a significant predictor of any of acute or late high-grade (> or =3) toxicity. IFI is an important prognosticator of OS and LRFS in patients with stage III NSCLC treated with Hfx RT with or without concurrent carboplatin/etoposide. IFI led to higher incidence only of hematological toxicity, but was not predictive of any acute or late high-grade (> or =3) toxicity. A carefully designed randomized trial seems necessary to give better insight into the issue of optimal IFI in this disease.

The efficacy of hyperbaric oxygen therapy in the treatment of radiation-induced late side effects

PURPOSE

We investigated the efficacy of hyperbaric oxygen therapy (HBOT) in the management of patients with radiation-induced late side effects, the majority of whom had failed previous interventions.

METHODS AND MATERIALS

Of 105 eligible subjects, 30 had either died or were not contactable, leaving 75 who qualified for inclusion in this retrospective study. Patients answered a questionnaire documenting symptom severity before and after treatment (using Radiation Therapy Oncology Group criteria), duration of improvement, relapse incidence, and HBOT-related complications.

RESULTS

The rate of participation was 60% (45/75). Improvement of principal presenting symptoms after HBOT was noted in 75% of head-and-neck, 100% of pelvic, and 57% of "other" subjects (median duration of response of 62, 72, and 68 weeks, respectively). Bone and bladder symptoms were most likely to benefit from HBOT (response rate, 81% and 83%, respectively). Fifty percent of subjects with soft tissue necrosis/mucous membrane side effects improved with HBOT. The low response rate of salivary (11%), neurologic (17%), laryngeal (17%), and upper gastrointestinal symptoms (22%) indicates that these were more resistant to HBOT. Relapse incidence was low (22%), and minor HBOT-related complications occurred in 31% of patients.

CONCLUSION

Hyperbaric oxygen therapy is a safe and effective treatment modality offering durable relief in the management of radiation-induced osteoradionecrosis either alone or as an adjunctive treatment. Radiation soft tissue necrosis, cystitis, and proctitis also seemed to benefit from HBOT, but the present study did not have sufficient numbers to reliably predict long-term response.

The effect of therapeutic irradiation on LactoSorb absorbable copolymer

Bioabsorbable implants continue to gain popularity in providing temporary internal fixation due to their many advantages over metallic internal fixation. Coincident with the presence of internal fixation devices, it may be necessary to use radiotherapy to treat tumors. While metal implants can alter the distribution of the radiotherapy beam, bioabsorbable polymer implants are, essentially, tissue equivalent. This ionizing irradiation, in sufficiently high dose, can affect polymers through chain scission and cross-linking and accelerate the hydrolysis of absorbable polymers. However, little is known about the effects of therapeutic doses on such materials. This study exposed LactoSorb (Biomet, Inc., Warsaw, IN) absorbable copolymer to doses of x-ray irradiation in a clinically relevant manner, in vitro, with individual doses of 2 Gy administered five days per week for up to eight weeks, yielding a total cumulative dose of up to 80 Gy. Specimens were tested both mechanically and for inherent viscosity. Overall, the LactoSorb specimens withstood exposure to the irradiation exceedingly well, providing empirical evidence of the suitability of this material for temporary internal fixation when subsequent radiotherapy in the region is probable.

A phase II study of concomitant hyperfractionated radiation therapy and double dose intra-arterial cisplatin for squamous cell carcinoma of the head and neck

This successor phase II study evaluates the tolerability and efficacy of concomitant hyperfractionated radiation therapy (HFX-RT) and double dose intra-arterial (IA) cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). In doing so, this study represents further resurgence of the potential use of IA chemotherapy in the management of SCCHN. This has been enabled by the evolution of angiographic catheter/microcatherter technology. Between 1997 and 1999, 24 patients with locally advanced T4/T3 SCCHN were treated with HFX-RT (76.8- 81.6 Gy at 1.2 Gy bid over 6-7 weeks) and high-dose IA cisplatin (150mg/m2 given at the start of and during RT boost treatment [start of week 6 and 7]). Twenty-two patients (92%) had T4 disease and 14 (58%) N2/ N3 disease. Acute toxicity was limited to two grade 4 (8%) and 19 grade 3 (79%) mucosal events; and single grade 3 hematologic, infectious and skin events. Eight patients (33%) were unable to receive the second planned dose of IA cisplatin. Twenty-two patients had complete response (92%) at the primary site. Among 17 patients with positive neck disease 12 (71%) achieved complete response in the neck. Follow-up ranges from 7-30 months (median = 18 months) with 14 patients alive without disease, 2 alive with disease, 7 dead of disease and 1 dead of intercurrent disease. While concomitant HFX-RT and double dose IA cisplatin as used in this study is associated with encouraging response rates in this highly unfavorable subset of patients with locally advanced SCCHN it was not feasible. Future investigation of this novel treatment strategy utilizing modern angiographic catheter/microcatherter technology will involve a single dose of IA cisplatin with HFX-RT and dose intensification using neoadjuvant therapy.

The optimal fraction size in high-dose-rate brachytherapy: dependency on tissue repair kinetics and low-dose rate

BACKGROUND AND PURPOSE

Indications of the existence of long repair half-times on the order of 2-4 h for late-responding human normal tissues have been obtained from continuous hyperfractionated accelerated radiotherapy (CHART). Recently, these data were used to explain, on the basis of the biologically effective dose (BED), the potential superiority of fractionated high-dose rate (HDR) with large fraction sizes of 5-7 Gy over continuous low-dose rate (LDR) irradiation at 0.5 Gy/h in cervical carcinoma. We investigated the optimal fraction size in HDR brachytherapy and its dependency on treatment choices (overall treatment time, number of HDR fractions, and time interval between fractions) and treatment conditions (reference low-dose rate, tissue repair characteristics).

METHODS AND MATERIALS

Radiobiologic model calculations were performed using the linear-quadratic model for incomplete mono-exponential repair. An irradiation dose of 20 Gy was assumed to be applied either with HDR in 2-12 fractions or continuously with LDR for a range of dose rates. HDR and LDR treatment regimens were compared on the basis of the BED and BED ratio of normal tissue and tumor, assuming repair half-times between 1 h and 4 h.

RESULTS

With the assumption that the repair half-time of normal tissue was three times longer than that of the tumor, hypofractionation in HDR relative to LDR could result in relative normal tissue sparing if the optimum fraction size is selected. By dose reduction while keeping the tumor BED constant, absolute normal tissue sparing might therefore be achieved. This optimum HDR fraction size was found to be largely dependent on the LDR dose rate. On the basis of the BED(NT/TUM) ratio of HDR over LDR, 3 x 6.7 Gy would be the optimal HDR fractionation scheme for replacement of an LDR scheme of 20 Gy in 10-30 h (dose rate 2-0.67 Gy/h), while at a lower dose rate of 0.5 Gy/h, four fractions of 5 Gy would be preferential, still assuming large differences between tumor and normal tissue repair half-times and equal overall treatment time. For the same fraction size, an even larger normal tissue sparing can be obtained by prolongation of the HDR overall treatment time.

CONCLUSION

Radiobiologic model calculations presented here aim to demonstrate that hypofractionation in HDR might have its opportunities for widening the therapeutic window, but definitely has its limits. For each specific combination of the parameters, a theoretical optimal HDR fraction size with regard to relative or absolute normal tissue sparing can be estimated, but because of uncertainty in the biologic parameters, these hypofractionation schemes cannot be generalized for all HDR brachytherapy indications.

Quantification of late complications after radiation therapy

BACKGROUND

An increasing number of patients survive cancer after having received radiation therapy. Therefore, the occurrence of late normal tissue complications among long-term survivors is of particular concern.

METHODS

Sixty-three patients treated by radical surgery and irradiation for rectal carcinoma were subjected to an unconventional sandwich therapy. Preoperative irradiation was given in four fractions of 5 Gy each applied within 2 or 3 days; postoperative irradiation consisted mostly of 15 x 2 Gy (range, 20-40 Gy). A considerable proportion of these patients developed severe late complications (Radiother Oncol 53 (1999) 177). The data allowed a detailed analysis of complication kinetics, leading to a new model which was tested using data from the literature.

RESULTS

Data on late complications were obtained for eight different organs with a follow-up of up to 10 years. For the various organs, the percentage of patients being free from late complications, plotted as a function of time after start of radiation therapy, was adequately described by exponential regression. From the fit, the parameter p(a) was obtained, which is the percentage of patients at risk in a given year of developing a complication in a given organ during that year. The rate p(a) remained about constant with time. Following sandwich therapy, the annual incidence of complications in the bladder, ileum, lymphatic and soft tissue, and ureters was about the same (p(a)=10-14%/year), whereas complications in bone or dermis occurred at lower rates (4.7 or 7.5%/year, respectively).

DISCUSSION

Numerous data sets collected from published reports were analyzed in the same way. Many of the data sets studied were from patients in a series where there was a high incidence of late effects. Three types of kinetics for the occurrence of late effects after radiotherapy were identified: Type 1, purely exponential kinetics; Type 2, exponential kinetics, the slope of which decreased exponentially with time; Type 3, curves composed of two components, a fast initial decline followed by an exponential decrease. For each kind of kinetics, provided that the dose distribution is not too heterogeneous, the incidence of late effects appears to occur at exponential or approximately exponential kinetics, even many years after treatment. This implies that a random process might be involved in the occurrence of late radiation sequelae.

CONCLUSIONS

There might be a lifelong risk of developing late complications, of which patients and clinicians should be aware. It appears worthwhile to try to identify, in follow-up examinations of patients after radiation therapy, what kind of processes might be involved in triggering subclinical residual injury to develop into a clinically manifest late effect.

High-dose intra-arterial cisplatin boost with hyperfractionated radiation therapy for advanced squamous cell carcinoma of the head and neck

PURPOSE

To evaluate the tolerance and efficacy of intra-arterial (IA) cisplatin boost with hyperfractionated radiation therapy (HFX-RT) in patients with advanced squamous cell carcinoma of the head and neck (SCCHN).

PATIENTS AND METHODS

Forty-two patients with locally advanced primary SCCHN were treated on consecutive phase I/II studies of HFX-RT (receiving a total of 76.8 to 81.6 Gy, given at 1.2 Gy bid) and IA cisplatin (150 mg/m(2) received at the start of and during RT boost treatment).

RESULTS

Acute grade 3 to 4 toxicities were as follows: grade 4 and grade 3 mucosal toxicity occurred in three (7%) and 31 patients (69%), respectively, and grade 3 hematologic, infectious, and skin events occurred in one patient each. Eight of 24 patients (33%) were unable to receive a second planned dose of IA cisplatin because of general anxiety (n = 5), nausea and/or emesis (n = 2), or asymptomatic occlusion of an external carotid artery (n = 1). Thirty-seven patients (88%) experienced complete response (CR) at primary site. Twenty-nine (85%) of 34 patients presenting with nodal disease experienced CR. The actuarial 2-year rates of locoregional control and disease-specific and overall survival are 73%, 63%, and 57%, respectively, with a median active follow-up of 30 months.

CONCLUSION

In this highly unfavorable subset of patients, these results seem superior to previously reported chemoradiation regimens in more favorable patients. Use of a second dose of IA cisplatin boost was associated with increased toxicity without obvious therapeutic gain. This novel strategy allows for an incremental increase in the treatment intensity of the HFX-RT regimen recently established as superior to once-a-day RT.

Influence of interfraction interval on the efficacy and toxicity of hyperfractionated radiotherapy in combination with concurrent daily chemotherapy in stage III non-small-cell lung cancer

PURPOSE

To investigate the influence of the interfraction interval (IFI) on treatment outcome and toxicity in hyperfractionated (HF) radiotherapy (RT) for Stage III non-small-cell lung cancer.

METHODS AND MATERIALS

Data for 301 patients treated with 1.2 Gy b.i.d. to a total of 69.6 Gy and concurrent chemotherapy in our 3 prospective studies were analyzed. The chemotherapy regimen was either (1) 50 mg each of carboplatin and etoposide (CE) given on RT days (163 patients) or (2) 30 mg of CE on RT days and 100 mg of CE on Saturdays and Sundays during the RT course (138 patients). An IFI of 4.5-5 h or 5.5-6 h had been nonrandomly assigned for each patient, and this interval was kept throughout the treatment.

RESULTS

No difference was observed in treatment outcome due to the chemotherapy protocol, and the 2 groups were combined. Patients treated with the shorter IFI had a better local control rate (38% at 5 years) and survival rate (30% at 5 years) than those treated with the longer interval (23% and 14%, respectively; p < 0.001). However, female patients and those with a high Karnofsky performance status score (KPS), weight loss of < or =5% in the previous 6 months, or Stage IIIA disease had been more often treated with the shorter IFI, and these characteristics were associated with better treatment outcome. In multivariate analysis, only gender, KPS, and weight change proved to be significant prognostic factors influencing both local control and survival, and the effect of IFI was not significant. The incidence of Grade 4 acute esophagitis tended to be higher in the shorter interval group (p = 0.072), but there were no differences in the incidence of late or other acute RT-related toxicities between the 2 groups.

CONCLUSIONS

The possible influence of the IFI on local control and survival could not be verified using multivariate analysis. To better understand the influence of the IFI, randomized studies with more patients and wider ranges of intervals (e.g., 5 h vs. 8 h) seem to be necessary.

Radiothérapie trifractionnée accélérée seule ou alternée avec la chimiothérapie chez des patients souffrant d’un cancer localement évolué de la sphère ORL : analyse de la toxicité tardive

PURPOSE

To assess late effects and quality of life in patients treated by three times daily (t.i.d.) radiotherapy with or without alternating chemotherapy for locally advanced squamous cell carcinoma of the head and neck.

PATIENTS AND METHOD

Between 1986 and 1991, 153 patients with locally advanced tumors have been included in a phase I/II study consisting of t.i.d. radiotherapy (4 h. between fractions) of 2 Gy/fraction to a total dose of 60 Gy, alternated or not with combination chemotherapy. The first group of patients received radiotherapy alone, the other group received combined modality. Ninety-two patients were eligible for late effect assessment: 61 in the combined modality group and 31 in the radiation therapy only group. The median follow-up was 45 months. All patients have been assessed according to the follow-up clinical records using the RTOG/EORTC classification. Twenty-nine patients, who were alive at the time of our study, received a questionnaire on their quality of life, and were invited for a clinical evaluation using the SOMA-LENT scale.

RESULTS

Ninety percent of the patients treated by radiation therapy alone developed one or more late complications. Overall, 47% of the patients have developed severe complications (grade III and IV): 42% in the group treated by radiation therapy alone and 49% in the group treated with combined modality. In the group treated by radiation therapy alone, the most commonly damaged organs were the mucosa (83%), skin (51%) and salivary glands (42%). We observed one case of osteonecrosis and one case of radiation myelitis. In the combined modality group, 95% of patients developed one or more late sequelae, of which 79% had skin, 51% mucosa and 42% salivary gland late effects, respectively. We observed four cases of osteonecrosis. Quality of life and overall physical condition of the patients have been judged to be average by self-questionnaire. Assessment according to the SOMA-LENT scale showed serious late effects mainly at the level of the salivary glands, mandibles and teeth. Correspondence between the RTOG/EORTC and the SOMA-LENT scale was mediocre.

CONCLUSION

This unconventional 4-h three times daily radiotherapy protocol resulted in very severe late effects on normal tissue. However, combination with chemotherapy resulted in minimal additional toxicity. We emphasise that the SOMA-LENT scale is neither simple to use nor easy to interpret. Quality of life is a very subjective notion and is not necessarily correlated with the objective seriousness of complications.

High-dose intra-arterial cisplatin and concurrent hyperfractionated radiation therapy in patients with locally advanced primary squamous cell carcinoma of the head and neck: report of a phase II study

BACKGROUND

This phase II study evaluates the tolerability and efficacy of concurrent hyperfractionated radiation therapy (HFX-RT) and high-dose intra-arterial (IA) cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN).

METHODS

Between December 1995 and November 1997, 20 patients with locally advanced T4/T3 SCCHN were treated with HFX-RT (76.8-79.2 Gy at 1.2 Gy bid over 6-7 weeks) and high-dose IA cisplatin (150 mg/m(2) given at the start of RT boost treatment [start of week 6]). Seventeen patients (85%) had T4 disease, and 14 (70%) had N2/ N3 disease.

RESULTS

Grade 3-5 acute toxicity was limited to one grade 4 (5%) and 14 grade 3 (70%) mucosal events. No grade 3/4 hematologic toxicity was observed. Median weight loss during therapy was 9% (range, 2%-16%). Eighteen patients had complete response (90%) at the primary site; 14 were confirmed pathologically. Among 17 patients with positive neck disease, 16 (94%) achieved complete response in the neck, including 12 of 13 patients with N2/N3 disease who underwent planned neck dissection. Active follow-up ranges from 12 to 32 months (median, 20 months) with 11 patients alive without disease, 5 dead of disease, and 4 dead of intercurrent disease. Eighteen patients (90%) remained disease free at the primary site, and the locoregional control rate is 80%.

CONCLUSIONS

High-dose IA cisplatin and concurrent HFX-RT as used in this study is feasible and warrants further investigation. The high complete response rate and low grade 4 toxicity in this highly unfavorable subset of patients appears better than previously reported chemoradiation regimens for more favorable patients.

A Radiation Therapy Oncology Group (RTOG) phase III randomized study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas: first report of RTOG 9003

PURPOSE

The optimal fractionation schedule for radiotherapy of head and neck cancer has been controversial. The objective of this randomized trial was to test the efficacy of hyperfractionation and two types of accelerated fractionation individually against standard fractionation.

METHODS AND MATERIALS

Patients with locally advanced head and neck cancer were randomly assigned to receive radiotherapy delivered with: 1) standard fractionation at 2 Gy/fraction/day, 5 days/week, to 70 Gy/35 fractions/7 weeks; 2) hyperfractionation at 1. 2 Gy/fraction, twice daily, 5 days/week to 81.6 Gy/68 fractions/7 weeks; 3) accelerated fractionation with split at 1.6 Gy/fraction, twice daily, 5 days/week, to 67.2 Gy/42 fractions/6 weeks including a 2-week rest after 38.4 Gy; or 4) accelerated fractionation with concomitant boost at 1.8 Gy/fraction/day, 5 days/week and 1.5 Gy/fraction/day to a boost field as a second daily treatment for the last 12 treatment days to 72 Gy/42 fractions/6 weeks. Of the 1113 patients entered, 1073 patients were analyzable for outcome. The median follow-up was 23 months for all analyzable patients and 41.2 months for patients alive.

RESULTS

Patients treated with hyperfractionation and accelerated fractionation with concomitant boost had significantly better local-regional control (p = 0.045 and p = 0.050 respectively) than those treated with standard fractionation. There was also a trend toward improved disease-free survival (p = 0.067 and p = 0.054 respectively) although the difference in overall survival was not significant. Patients treated with accelerated fractionation with split had similar outcome to those treated with standard fractionation. All three altered fractionation groups had significantly greater acute side effects compared to standard fractionation. However, there was no significant increase of late effects.

CONCLUSIONS

Hyperfractionation and accelerated fractionation with concomitant boost are more efficacious than standard fractionation for locally advanced head and neck cancer. Acute but not late effects are also increased.

Altered fractionation in definitive irradiation of squamous cell carcinoma of the head and neck

The likelihood of local control after radiation therapy may be improved by increasing total dose or decreasing overall time. The probability of late complications increases with dose per fraction. Altered fractionation techniques usually employ two or more fractions per day using a dose per fraction that is similar or less than that employed in conventional fractionation. Altered fractionation may be broadly classified as hyperfractionation or accelerated fractionation. Data suggest that altered fractionation schedules may improve local control (and to a lesser extent, survival) compared with conventional irradiation.

Accelerated hyperfractionated radiotherapy in 149 patients with glioblastoma multiforme

Between August 1986 and December 1997, 149 patients with glioblastoma were treated postoperatively with 1.5 Gy fractions three times daily to a total dose of 54 Gy with 4-h intervals. Median actuarial survival was 8.8 months. Survival was 31% at 12 months and 4% at 24 months. No severe acute toxicity occurred. Multivariate analysis revealed that only age < or = 60 years and lactate dehydrogenase levels < or = 240 U/l predicted significantly higher survival probabilities.

Phase I/II trial of radiation with chemotherapy "boost" for advanced squamous cell carcinomas of the head and neck: toxicities and responses

PURPOSE

Extrapolating from our experience delivering a "boost" field of radiation concurrently with fields treating both gross and subclinical disease at the end of a course of radiation therapy, we developed a regimen to deliver concurrent chemotherapy during the last 2 weeks of a conventionally fractionated course of radiation.

PATIENTS AND METHODS

Patients had stage III or IV biopsy-proven squamous cell carcinoma originating from a head and neck mucosal site. The regimen was 70 Gy delivered over 7 weeks with concurrent fluorouracil (5-FU) and cisplatin given daily with each radiation dose during the last 2 weeks. A phase I study was performed to determine the maximum-tolerated dose (MTD) before a phase II study was conducted.

RESULTS

The MTD was 400 mg/m(2) per day for 5-FU and 10 mg/m(2) per day for cisplatin. Mucositis persisting more than 6 weeks after therapy was the dose-limiting toxicity. A total of 60 patients were treated on the two phases of the study. Eighteen patients (35%) treated at the MTD developed prolonged mucositis. There were two cases of neutropenic sepsis, including one fatality. The actuarial 2-year rates for overall survival, freedom from relapse, and local control were 62%, 59%, and 80%, respectively.

CONCLUSION

Preliminary locoregional control rates seem to be higher than those reported for treatment with radiation alone. Toxicity was also greater than that seen with radiation alone, but the regimen was designed to deliver an intense treatment schedule, which could be completed without significant interruptions, and to obtain high control rates above the clavicles. These end points were achieved.

Altered fractionation in radiation therapy for squamous-cell carcinoma of the head and neck

Following is a review of altered fractionation in radiation therapy for head and neck cancer. The goals of altered fractionation are to increase local-regional control and/or reduce the risk of late complications. Altered fractionation schedules can be broadly classified as accelerated fractionation and hyperfractionation. Data indicate that some of these schedules, particularly hyperfractionated radiation therapy, offer improved results compared to conventionally fractionated radiation therapy. Most investigators have observed no significant increased risk of late complications with the dose-fractionation schedules described.

Toxicity antagonists in head and neck cancer

Clinical trials of altered fractionation and concurrent chemoradiation regimens have better elucidated the limits of both acute and late normal tissue toxicities in the head and neck. Acute effects on mucosal epithelium represent the principal barrier to intensification of radiation or chemoradiation schedules. Late soft tissue injury and organ dysfunction limit efforts to escalate radiation total dose. New insights into the cellular and molecular mechanisms of injury repair allow new strategies in the management and prevention of treatment-related toxicity. Toxicity antagonists are agents that directly interfere with the mechanism of toxicity or modulate the normal tissue response to injury. This article reviews 10 agents under development. Not only could such interventions reduce treatment-related morbidity, but they may also allow treatment intensification in advanced disease.

Long-term results of accelerated radiation treatment for advanced head and neck cancer

BACKGROUND AND PURPOSE

This report presents long-term follow-up data from a prospective but unrandomized trial of a continuous 3.5-week course of accelerated radiation treatment (ART) used as primary treatment for patients with loco-regionally advanced head and neck cancer.

MATERIALS AND METHODS

Ninety-three patients in three centres in New Zealand and Australia were treated with ART (59.40 Gy in 33 fractions over 24-25 days). Their disease originated from three anatomical regions (oral cavity, 35 patients; pharynx, 31 patients; larynx, 27 patients). Seventy-nine of these patients had stage III or IV cancers.

RESULTS

Follow-up ranged from 68 to 203 months (median 139 months). Loco-regional (LR) failure occurred in 52 patients leading to a 10-year actuarial expectation of LR control of 38%. The actuarial expectation of LR control at 10 years was highly dependent on stage and for stage III, IVA and IVB patients it was 57+/-8.1%, 32+/-1.7% and 7+/-0.5%, respectively. Multivariate analysis could not confirm an independent impact of primary site or histological differentiation on LR failure. Two patients died of acute toxicity of treatment and six patients developed grade 3/4 late complications affecting soft tissues only, yielding an actuarial expectation of complications of this severity at 5 years of 9%. No cases of osteoradionecrosis or myelitis were observed.

CONCLUSION

This ART, which has proved easy to use at a number of large and small centres, has produced encouraging long-term LR control at a cost of limited soft tissue morbidity.

Split-course accelerated hyperfractionation radiotherapy for advanced head and neck cancer: influence of split time and overall treatment time on local control

We analyzed 52 patients with stage III and IV head and neck cancer who were given split-course accelerated hyperfractionated radiotherapy with curative intent, focusing particularly on the influence of split-time on local control. An initial complete response was achieved in 16 patients (31%), and the rate of persistent local control at 3 years was 23%. The cause specific survival rate at 3 years was 29%. Univariate analysis of local control according to the split-time duration and overall treatment time showed that shorter duration (< or = 14 days or < or = 45 days, respectively) had a significantly positive impact on local control (P < 0.05). Multivariate analysis using local control as an endpoint also demonstrated that gender (women showing a better outcome than men) and split-time (< or = 14 days was better than > 14 days) were statistically significant factors for local control. These results suggest that shortening the split-time during radiotherapy might improve local control in accelerated hyperfractionation.

Lack of influence of sequence of top-up doses on repair kinetics in rat spinal cord

BACKGROUND AND PURPOSE

The rat spinal cord model was used to determine whether repair kinetics changed during a course of fractionated radiotherapy if twice daily doses were given either at the initial or final period of a concomitant boost irradiation schedule.

MATERIALS AND METHODS

The rat cervical spinal cord was irradiated from C2-T2 in 870 animals with top-up doses of three daily fractions of 9 Gy representing 75% of the biologic dose at the ED50 level for white matter necrosis. To simulate concomitant boost protocols, these top-up doses were given either preceding (initial top-up) or following (final top-up) a b.i.d. schedule of 1 Gy/F delivered at 0, 1, 2, 4, 8 or 24 h interfraction intervals. The end point was forelimb paralysis secondary to white matter necrosis.

RESULTS

For interfraction intervals of 0, 1, 2, 4, 8 and 24 h, the initial top-up schedules yielded ED50 values of 18.2, 19.2, 23.7, 21.3, 27.2 and 29.7 Gy, respectively; the corresponding ED50s from the final top-up schedules were 17.5, 19.0, 20.7, 21.2, 26.9 and 30.3 Gy, respectively. A 10% reduction in the ED50 value from pooled data was observed when the interfraction interval was reduced from 24 (ED50 = 30.3 Gy) to 8 h (ED50 = 27.1 Gy). Fitting the incomplete repair (IR) version of the LQ model with mono-exponential repair kinetics gave alpha/beta values of 1.4 and 1.5 Gy, and similar repair half-times of 4.3 and 5.0 h for the initial and final top-up experiments, respectively. The IR model with bi-exponential repair kinetics did not provide a better fit to the data.

CONCLUSIONS

We conclude that the sequence of top-up doses has no apparent influence on radiation sensitivity or repair kinetics in the rat spinal cord. The clinical implication is that the interfraction interval but not the timing of the boost is a critical determinant of spinal cord tolerance in concomitant boost protocols.

Impact of the interfraction interval on clonogenic cell survival in split-dose irradiation of R1H rhabdomyosarcoma of the rat in vitro

PURPOSE

In a previous study, the response of the R1H rhabdomyosarcoma of the rat to conventional irradiation (1.83-2.75 Gy fractions once-daily) and hyperfractionated radiotherapy (0.92-1.38 Gy fractions with different time intervals between the two daily fractions) was investigated [Kleineidam, M., Pieconka, A., Beck-Bornholdt, H.-P. Radiotherapy of the rhabdomyosarcoma R1H of the rat: influence of the time interval between two daily fractions during hyperfractionated radiotherapy. Radiother. Oncol. 30: 128-132, 1994]. Compared to once-daily irradiation, interfraction intervals of 2 h led to reduced tumour response, due to recovery from sublethal damage, and intervals of 5-6 h resulted in increased tumour response, possibly due to cell cycle effects. The purpose of the present study was to complement these tumour data by measuring clonogenic cell survival of R1H cells in vitro after split-dose irradiation.

METHODS AND MATERIALS

Experiments were performed with 2 x 2.5 Gy and 2 x 3.5 Gy either at 21 degrees C (preventing cell cycle progression) or at 37 degrees C (allowing for cell cycle effects).

RESULTS

For 3.5 Gy fractions, a cell survival curve equivalent to the in vivo results was obtained with the lowest surviving fraction observed at time intervals of 6-7 h, but only when cells were incubated at 37 degrees C during the interval. This phenomenon was absent in the 21 degrees C experiments.

CONCLUSIONS

Our data provide further evidence to support the hypothesis that cell cycle effects are responsible for such observations. We conclude that the length of the interfraction interval has a considerable potential effect on tumour response to altered fractionation regimens.

Hyperfractionation: where do we stand?

Hyperfractionation is generally expected to allow an escalation of total dose, thereby increasing tumour control rate, without increasing the risk of late complications. The purpose of this review is to assess the empirical evidence for this therapeutic gain from hyperfractionated radiotherapy. Although extensive clinical data have been accumulated until now, especially on treatment of head and neck cancer, the line of evidence is not consistent. The present analysis indicates that the dose per fraction generally used in standard radiotherapy is already a good choice.

Risk factors and dose-effect relationship for osteoradionecrosis after hyperfractionated and conventionally fractionated radiotherapy for oral cancer

A high frequency of osteoradionecrosis after hyperfractionated radiotherapy (RT) of head and neck tumours led to a detailed analysis of risk factors in the dental, surgical, and radiotherapeutic areas. 168 patients with oral cancer were analysed retrospectively. 19% of them had been irradiated primarily and 81% postoperatively. 116 patients received a total dose mostly ranging from 60 Gy to 70 Gy to the ICRU 29 reference point (daily single dose 2 Gy). 52 patients were treated hyperfractionally with two daily fractions of 1.2 Gy per day, 4 h minimum apart and a total dose 82.8 Gy. Dental findings could be evaluated in 126 patients. Factors were checked for prognostic significance for osteoradionecrosis (ORN). Dose dependency was computed using a PROBIT analysis. Dental status before radiotherapy was generally poor (mean 11/32 teeth present, of these 1 was dead, 2.4 carious, 2.4 loose, 0.3 destroyed). On average, six teeth (range 0-27 teeth) had to be extracted. In one-third of the patients bone surgery was necessary. ORN occurred in 8.6% of the patients treated conventionally but in 22.9% of those treated hyperfractionally (p = 0.029). Biologically effective dose (p = 0.032) and deep paradontitis (p = 0.034) proved to be significant risk factors for ORN. PROBIT analysis showed a steadily rising dose dependency of the ORN frequency after conventional radiotherapy. Using total doses up to 70 Gy the frequency of ORN was 8.6%. Dose escalation using hyperfractionation led to an intolerable ORN frequency (22.9%) where a short interfraction interval was a significant factor. The use of this dose fractionation was therefore discontinued in 1992.

The time course of development of late side effects after irradiation of the prostate with multiple fractions per day

BACKGROUND AND PURPOSE

A group of patients with prostate cancer was irradiated in the early 1980s with a TID schedule, resulting in a very high frequency of side effects. The time course of development of severe late complications was evaluated.

MATERIALS AND METHODS

We retrospectively reviewed the records of 91 patients with prostate cancer, irradiated on a linear accelerator or a cobalt unit between 1980 and 1983. They received a split-course irradiation with multiple fractions per day (MFD) up to a nominal dose of 60 Gy. The rate of development of severe late urological and gastrointestinal complications, grade 3 or more according to the RTOG scoring system, was analysed.

RESULTS

The 5-year actuarial incidence of urological complications was 51%. After a lag time of a few months, patients develop "first events' at a nearly constant rate of 10% for 5 years after treatment. Subsequent events ("all events') seem to continue to appear even after 5 years. The actuarial incidence at 5 years of gastrointestinal complications was 14%, with no new events developing later than 3 years after treatment.

CONCLUSIONS

The irradiation schedule used resulted in an unacceptable high incidence of late side effects, probably due to incomplete repair between fractions. MFD fractions to the pelvis should be avoided, unless sufficient time in between fractions can be allowed. Moreover, the fact that after this treatment schedule with very pronounced biological effects, new severe complications continued to develop up to 5 years after therapy, indicates that sufficiently long follow-up time has to be respected when investigating new radiation techniques for pelvic tumours.

Evolution of the Radiation Therapy Oncology Group clinical trials for head and neck cancer

During the past 25 years, the Radiation Therapy Oncology Group (RTOG) has played a major role in head and neck cancer clinical research. The major research themes for recent and currently active trials have been: (a) combined modality therapy, (b) altered fractionation radiotherapy, (c) hypoxic cell sensitizers, (d) organ preservation, (e) chemoprevention, and (f) clinical/laboratory correlations. For advanced operable disease, the RTOG showed improved local-regional control with postoperative radiotherapy as compared to preoperative radiotherapy for carcinoma of the supraglottic larynx and hypopharynx. This established the use of surgery followed by postoperative radiotherapy as the standard treatment in subsequent RTOG and Intergroup trials for operable disease. For advanced inoperable disease, the RTOG demonstrated the feasibility of testing altered fractionation radiotherapy in a multiinstitutional clinical trials setting. A Phase III trial comparing hyperfractionation and accelerated fractionation to conventional fractionation is now in progress. Phase I/II combined modality studies established the efficacy of concurrent high-dose cisplatin and radiotherapy in the treatment of advanced disease and provided the basis for further testing in Phase III trials for nasopharyngeal carcinoma, larynx preservation, and high-risk advanced operable disease. Analysis of the extensive RTOG Head and Neck Cancer database established the incidence of second malignancies and their adverse impact on patients whose initial tumors were cured by radiotherapy, and provided the basis for chemoprevention trials. Recursive partitioning analysis identified 6 distinct prognostically homogeneous patient groups based on pretreatment tumor or patient characteristics and/or treatment variables. Retrospective analysis identified tumor p105 antigen density as an independent prognostic indicator in patients irradiated for head and neck cancer. Future trials will continue to focus on the reduction of morbidity and mortality, and improvement of the quality of life of head and neck cancer patients through innovative radiotherapy delivery, multimodality approaches, use of chemical and biological modifiers, and other novel therapies, identification of clinical and biological prognostic indicators, and prevention or diminution of acute morbidity and late complications of the disease and its treatment.