Residual radiation-induced injury in dermal tissue: implications for retreatment

Evaluation of Reirradiation in Locally Advanced Head and Neck Cancers: Toxicity and Early Clinical Outcomes

Objectives

Locoregional recurrence is the predominant pattern of treatment failure in advanced head and neck cancers. Reirradiation is a useful modality to treat inoperable head and neck cancer patients with recurrent disease. The aim of the present study was to analyze the treatment toxicity and early clinical outcomes in patients undergoing reirradiation.

Methods

Twenty patients of head and neck cancers with recurrences or second cancers were evaluated. Reirradiation was done using simultaneous integrated boost volumetric modulated arc therapy (SIB VMAT), intensity modulated radiotherapy (IMRT), or conventional radiotherapy using 6MV photons. Dose prescription ranged from 30 to 60 Gy in conventional fractionation.

Results

Seventeen males and three females were evaluated in this analysis. The median age of patients under study was 56.5 years. At time of analysis 8 patients (40%) had a complete response, 7 patients (35%) had progressive disease, and 25% had partial response or stable disease. Grade III-IV mucositis, dermatitis, xerostomia, dysphagia, and trismus were seen in 20%, 20%, 50%, 35%, and 45% patients, respectively, during retreatment. Patients receiving a radiotherapy dose less than 45 Gy showed a higher incidence of progressive disease (p = 0.01). The median disease-free survival for patients receiving reirradiation dose of ≥46 Gy was 19 ± 3.3 months (median ± S Error) compared to 8 ± 2.61 months for those with a dose prescription less than 45 Gy (p = 0.03). At 18-month follow-up 26% of patients undergoing reirradiation were disease-free.

Conclusions

Our results show improved tumor control using a prescription of doses ≥46 Gy in retreatment setting.

Re-irradiation and Hyperthermia in Breast Cancer

Half of locoregional recurrences after breast cancer treatment are isolated events. Restaging should be carried out to select patients for curative salvage treatment. The approach depends on the characteristics of the primary and recurrent cancer, previous locoregional and systemic treatments, site of recurrence, comorbidities and the patient's wishes. A multidisciplinary discussion should be associated with the shared decision-making process. In view of the potential long-term disease-free survival, meticulous target volume delineation and selection of the most appropriate techniques should be used to decrease the risk of toxicity. This overview aims to provide clinicians with tools to manage the different scenarios of breast cancer patients with locoregional recurrences in the context of re-irradiation.

Stereotactic body radiation therapy in the re-irradiation situation--a review

Although locoregional relapse is frequent after definitive radiotherapy (RT) or multimodal treatments, re-irradiation is only performed in few patients even in palliative settings like e.g. vertebral metastasis. This is most due to concern about potentially severe complications, especially when large volumes are exposed to re-irradiation. With technological advancements in treatment planning the interest in re-irradiation as a local treatment approach has been reinforced. Recently, several studies reported re-irradiation for spinal metastases using SBRT with promising local and symptom control rates and simultaneously low rates of toxicity. These early data consistently indicate that SBRT is a safe and effective treatment modality in this clinical situation, where other treatment alternatives are rare. Similarly, good results have been shown for SBRT in the re-irradiation of head and neck tumors. Despite severe late adverse effects were reported in several studies, especially after single fraction doses >10 Gy, they appear less frequently compared to conventional radiotherapy. Few studies with small patient numbers have been published on SBRT re-irradiation for non-small cell lung cancer (NSCLC). Overall survival (OS) is limited by systemic progression and seems to depend particularly on patient selection. SBRT re-irradiation after primary SBRT should not be practiced in centrally located tumors due to high risk of severe toxicity. Only limited data is available for SBRT re-irradiation of pelvic tumors: feasibility and acceptable toxicity has been described, suggesting SBRT as a complementary treatment modality for local symptom control.

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

[Reirradiation of normal tissues: preclinical radiobiological data]

Reirradiation represent an unfrequent particular clinical situation. The risk/benefit ratio assessment must be taken into account, considering both clinical and dosimetric aspects. There is a relatively limited amount of preclinical data available to date and clinicians should cautiously perform reirradiations in selected indications. This review summarizes the experimental data available on reirradiation of normal tissues, the consequences on early and late toxicities as well as the intrinsic limitations of these models.

Fluoroscopically guided interventional procedures: a review of radiation effects on patients' skin and hair

Most advice currently available with regard to fluoroscopic skin reactions is based on a table published in 1994. Many caveats in that report were not included in later reproductions, and subsequent research has yielded additional insights. This review is a consensus report of current scientific data. Expected skin reactions for an average patient are presented in tabular form as a function of peak skin dose and time after irradiation. The text and table indicate the variability of reactions in different patients. Images of injuries to skin and underlying tissues in patients and animals are provided and are categorized according to the National Cancer Institute skin toxicity scale, offering a basis for describing cutaneous radiation reactions in interventional fluoroscopy and quantifying their clinical severity. For a single procedure performed in most individuals, noticeable skin changes are observed approximately 1 month after a peak skin dose exceeding several grays. The degree of injury to skin and subcutaneous tissue increases with dose. Specialized wound care may be needed when irradiation exceeds 10 Gy. Residual effects from radiation therapy and from previous procedures influence the response of skin and subcutaneous tissues to subsequent procedures. Skin irradiated to a dose higher than 3-5 Gy often looks normal but reacts abnormally when irradiation is repeated. If the same area of skin is likely to be exposed to levels higher than a few grays, the effects of previous irradiation should be included when estimating the expected tissue reaction from the additional procedure.

Improving surgical wound healing with basic fibroblast growth factor after radiation

OBJECTIVES/HYPOTHESIS

Delayed wound healing in surgical patients who have received previous irradiation continues to be a significant problem. We investigated whether radiation decreases basic fibroblast growth factor (bFGF) production in skin and whether supplemental bFGF can improve irradiated postsurgical soft tissue healing.

STUDY DESIGN

Experimental study in the porcine skin flap model.

METHODS

Pigs were subjected to orthovoltage radiation (1,300 cGy). To test whether radiation alters bFGF production in skin, semiquantitation of bFGF message was compared in irradiated and nonirradiated skin by reverse transcription-polymerase chain reaction (RT-PCR). To determine whether supplemental bFGF can improve postsurgical soft tissue healing after radiation, bFGF was given intravenously or intracuticularly preoperatively. To investigate whether additional oxygen tissue levels would modify the effects of supplemental bFGF, one test group received hyperbaric oxygen. Six weeks later, 108 skin flaps (random and arterial) were created in 27 pigs and monitored over 2 weeks. Tissues were analyzed for flap viability, vascularity, endothelial cell apoptosis by caspase-3 activation, and histologic analysis.

RESULTS

Radiation statistically increased endothelial cell apoptosis in porcine skin by 650%. Radiation also significantly reduced bFGF message by 75% in porcine skin by RT-PCR analysis. Supplemental intravenous bFGF in irradiated tissue significantly increased skin flap viability by 25% compared with controls (P < .001). Intravenous bFGF also significantly reduced gastrointestinal side effects from irradiation by 50% compared with controls. BFGF treatment induced a trend to decrease endothelial cell apoptosis in irradiated skin, but this was not statistically significant. Histologically, the intravenous bFGF-treated flaps had similar cellularity, fibroblasts, and extracellular acid mucopolysaccharides as controls. When bFGF was administered by intracuticular injection with and without hyperbaric oxygen, skin flap survival and flap vascularity were similar to controls.

CONCLUSIONS

Decreased local levels of bFGF in skin may play an important role in the delayed healing of irradiated wounds. Radiation appears to decrease bFGF production by significantly reducing bFGF message in irradiated tissue. Supplemental intravenous bFGF reduced irradiated soft tissue injury and improved random skin flap viability in this porcine model. More studies are needed to investigate the effects of bFGF in the surgical healing of irradiated wounds.

Re-irradiation in conjunction with liposomal doxorubicin for the treatment of skin metastases of recurrent breast cancer: a radiobiological approach and 2 year of follow-up

Thirty patients with local relapses after radical mastectomy and radiotherapy and undergoing infusion of liposomal doxorubicin (40 mg/m(2) monthly for 6 months) were randomized to receive re-irradiation. Radiotherapy was with either 17 fractions of 1.8 Gy, 5 days a week (N=15, group A) or 4 Gy plus two fractions of 3 Gy the 1st week and six fractions of 3 Gy given every second day (N=15, group B). Eight patients from group A (53.3%) and nine patients (60%) from group B demonstrating a clinically complete response (P=0.9). Grade I/II acute skin toxicity was monitored in 26.6% of patients in group A versus 73.3% in group B. The radiation schedule of group A seems superior for grade I/II acute (P=0.027) and late (P=0.015) skin toxicity. The linear quadratic model enabled the prediction of tumor response as well as normal skin reactions.

Tissue tolerance to reirradiation

There are increasing requests for delivering a second course of radiation to patients who develop second primary tumors within or close to previous radiotherapy portal or late in-field recurrences. Rational treatment decisions demand rather precise knowledge on long-term recovery of occult radiation injury in various organs. This article summarizes available experimental and clinical data on the effects of reirradiation to the skin, mucosa, gut, lung, spinal cord, brain, heart, bladder, and kidney. The data reveal that, in general, acutely responding tissues recover radiation injury within a few months and, therefore, can tolerate another full course of radiation. For late toxicity endpoints, however, tissues vary considerably in their capacity to recover from occult radiation damage. The heart, bladder, and kidney do not exhibit long-term recovery at all. In contrast, the skin, mucosa, lung, and spinal cord do recover subclinical injury partially to a magnitude dependent on the organ type, size of the initial dose, and, to a lesser extent, the interval between radiation courses. The available clinical data have inspired many radiation oncologists to undertake systematic studies addressing the efficacy and toxicity of reirradiation in various clinical settings. Hopefully, systematic scoring, collection, and analysis of patient outcome will produce quantitative data useful for clinical practice.

[Hyperfractionated reirradiation after salvage surgery in cervico-facial carcinoma. Result of a pilot study in 14 patients]

PURPOSE

Between November 1988 and May 1992, 14 patients were enrolled in a pilot study to evaluate the feasibility and results of hyperfractionated reirradiation for the treatment of head and neck recurrences or of second primary tumors developed in a previously irradiated volume.

MATERIALS AND METHODS

All patients underwent a surgical resection for the treatment of their recurrence or second cancer. Reirradiation was proposed because of positive margins and/or lymph node metastasis with extra-capsular spread. The planned reirradiation dose was 60 Gy over 5 weeks, with two daily fractions of 1.2 Gy delivered 6-8 hours apart.

RESULTS

Of the 14 patients, 10 received the reirradiation scheduled dose (ie, 60 Gy). All patients experienced an acute mucositis that never led to disruption of the treatment. Ten patients died 3 to 41 months after reirradiation (mean: 14 months), three were disease-free 48 to 71 months after reirradiation and one was alive with local progressive disease 74 months after reirradiation. The overall local control rate within the reirradiated volume was 43%. The 24- and 36-month overall survival rates were 50 and 35%, respectively. Overall, 13 late complications were noted: four were grade 1, seven were grade 2, and two were grade 3. Three patients still alive in September 1993 and whose initial files were available were enrolled in an additional study to assess from dose-volume histograms the cumulative doses delivered by the two irradiations.

CONCLUSION

Despite poor local control, reirradiation using a hyperfractionation schedule with high dose level is feasible in terms of acute and late toxicity.

Re-irradiation of soft-tissue sarcoma

Re-irradiation for local recurrence of malignancy after radical radiotherapy is of proven benefit at head and neck sites but has seldom been used elsewhere. This paper reports a series of 10 patients re-irradiated with external-beam techniques for local recurrence of soft-tissue sarcoma of the limb and limb girdle following initial limb conserving management with surgery and radiotherapy (dose range 33-60 Gy). Median survival was 14 months following re-treatment. Two cases received treatment with high-energy electrons and the rest with megavoltage photons. Five patients re-treated with radical intent (dose range 40-60 Gy) had a median survival of 36 months and median recurrence-free survival of 16 months. All five patients treated palliatively (dose range 12-50 Gy) have died, although two demonstrated local control until death. Acute reactions were not severe. Radionecrosis was seen in one patient who was re-irradiated twice (total dose 145 Gy) and subsequently required amputation. One other case required amputation for persistent local disease, but in the remaining eight, limb conservation was achieved. Re-irradiation of soft-tissue offers good local control and may avoid amputation.