Early and Late Complications Following Dynamic Stereotactic Radiosurgery and Fractionated Stereotactic Radiotherapy

Evaluation of results of linac-based radiosurgery for brain metastases from primary lung cancer

AIM

The purpose of our review was to evaluate results of radiosurgery for patients with brain metastases from lung cancer.

BACKGROUND

Lung cancer is the leading cause of death from cancer and the most common source of brain metastases. Radiosurgery allows the precise focal delivery of a high single radiation dose to brain metastases and results in high rates of local control.

MATERIALS AND METHODS

83 patients were treated between 2006 and 2008. We evaluated local control and outcome after radiosurgery and identified prognostic factors.

RESULTS

Median survival in the whole group was 7.8 months from radiosurgery and 11 months from diagnosis. Median survival in classes I, II and III was 13.2, 8.2 and 2.2 months. For 94% of patients symptoms improved or stabilised at the first follow-up visit and this status did not change during 7.1 months. According to the univariate analysis, factors associated with improved survival included: RPA class 1 compared with RPA 2 and 3, RPA class 2 compared with RPA 3, KPS > 70, control of the primary disease, radiosurgery performed more than once, level of haemoglobin >7 mmol/1, absence of extracranial metastases, volume of the biggest lesion <11 cm(3). The multivariate analysis confirmed a significant influence on survival for the following factors: RPA class 1 as compared with RPA 3, KPS > 70, absence of extracranial metastases, multiplicity of radiosurgery.

CONCLUSIONS

Stereotactic radiosurgery is a safe and effective treatment. It proved to be effective and safe in older patients. Selection of patients who are likely to benefit most should be based on prognostic factors. KPS proved to be the most important prognostic factor. In the RPA III group (patients with KPS < 70) survival time was similar to that achieved after symptomatic medical management.

Management of epilepsy in oncological patients

INTRODUCTION

Comorbidity between epilepsy and cancer is elevated. As a life-time condition, it is not impossible for a patient with epilepsy to have a cancer at some point. Besides, at least 30% of patients with primary brain tumors have epileptic seizures, but also in patients with metastatic infiltrating lesions of the central nervous system and with extracerebral tumors, epilepsy can be related. Seizures may also appear associated with paraneoplastic syndromes, such as limbic encephalitis and metabolic and infectious complications of chemotherapy and radiotherapy.

RESULTS

The precise mechanisms by which brain tumors and the other conditions mentioned above produce seizures are not fully understood, but are reviewed in this article, as well as the many different therapeutic options that may be used in the treatment of epileptic seizures. Pharmacological treatment poses various controversies, such as the utility of prophylactic treatment, interactions between antiepileptic drugs (AEDs) and chemotherapeutic drugs and the complications derived from the adverse effects of AEDs in this population. Finally, other treatments are proposed such as chemotherapy, radiotherapy and surgery, the rational application of which allows for an improvement in the patients' quality of life.

CONCLUSION

In order to arrive at a diagnosis, the different causes that could condition the appearance of epileptic seizures in cancer patients must be known. After this, the most adequate treatment should be chosen, thus ensuring the comprehensive treatment of cancer and epilepsy.

Killing two birds with one stone: a dosimetric study of dual target radiosurgery using a single isocenter

The treatment of hematogenous brain metastases is a frequent indication for stereotactic radiosurgery (SRS). It is common for more than one metastasis to be treated during the same SRS session. We retrospectively identified four cases where our m3 micro multileaf collimator (mMLC) was used to create two distinct apertures and treat adjacent lesions using a single isocenter. For these four cases, single isocenter plans with static conformal beams were dosimetrically compared to plans utilizing two isocenters with static conformal beams or conformal arcs. The effects on dose homogeneity, dose conformity, and the minimum isodose separating the two targets are minor and variable. On the other hand, the use of a single isocenter technique consistently halves delivery time and decreases the integral dose to normal tissue. For small adjacent metastases, which can simultaneously be encompassed within the high-resolution portion of the m3/Novalis mMLC collimator, the use of a single rather than a dual isocenter technique is feasible and generally advantageous.

Radiotherapy and chemotherapy of brain metastases

The authors have reviewed the results, the indications and the controversies regarding radiotherapy and chemotherapy of patients with newly diagnosed and recurrent brain metastases. Whole-brain radiotherapy, radiosurgery, hypofractionated stereotactic radiotherapy, brachytherapy and chemotherapy are the available options. New radiosensitizers and cytotoxic or cytostatic agents are being investigated. Adjuvant whole brain radiotherapy, either after surgery or radiosurgery, and prophylactic cranial irradiation in small-cell lung cancer are discussed, taking into account local control, survival, and risk of late neurotoxicity. Increasingly, the different treatments are tailored to the different prognostic subgroups, as defined by Radiation Therapy Oncology Group RPA Classes.

Five year results of LINAC radiosurgery for arteriovenous malformations: outcome for large AVMS

PURPOSE

For radiosurgery of large arteriovenous malformations (AVMs), the optimal relationship of dose and volume to obliteration, complications, and hemorrhage is not well defined. Multivariate analysis was performed to assess the relationship of multiple AVM and treatment factors to the outcome of AVMs significantly larger than previously reported in the literature.

METHODS AND MATERIALS

73 patients with intracranial AVMs underwent LINAC radiosurgery. Over 50% of the AVMs were larger than 3 cm in diameter and the median and mean treatment volumes were 8.4 cc and 15.3 cc, respectively (range 0.4-143.4 cc). Minimum AVM treatment doses varied between 1000-2200 cGy (median: 1600 cGy).

RESULTS

The obliteration rates for treatment volumes < 4 cc, 4-13.9 cc, and > or = 14 cc were 67%, 58%, and 23%, respectively. AVM obliteration was significantly associated with higher minimum treatment dose and negatively associated with a history of prior embolization with particulate materials. No AVM receiving < 1400 cGy was obliterated. The incidence of post-radiosurgical imaging abnormalities and clinical complications rose with increasing treatment volume. For treatment volumes > 14 cc receiving > or = 1600 cGy, the incidence of post-radiosurgical MRI T2 abnormalities was 72% and the incidence of radiation necrosis requiring resection was 22%. The rate of post-radiosurgical hemorrhage was 2.7% per person-year for AVMs with treatment volumes < 14 cc and 7.5% per person-year for AVMs > or = 14 cc.

CONCLUSION

As AVM size increases, the dose-volume range for the optimal balance between successful obliteration and the risk of complications and post-radiosurgical hemorrhage narrows.

Fractionated stereotactic radiotherapy of small intracranial malignancies

PURPOSE

To retrospectively evaluate the effectiveness of fractionated stereotactic radiotherapy (FSRT) in patients with small intracranial malignancies.

METHODS AND MATERIALS

From July 1991 to March 1997, 80 patients with a total of 121 brain or skull-base tumors were treated with FSRT alone, and were followed for periods ranging from 3 to 62 months (median 9.8). The majority of patients received 42 Gy in 7 fractions over 2.3 weeks, but in July 1993, protocols using smaller fraction doses were introduced for patients whose radiation-field diameters were larger than 3 cm or whose tumors were close to critical normal tissues.

RESULTS

For 64 patients with metastatic brain tumors the overall median survival was 8.3 months and 1-year actuarial survival rate was 33%. Significant prognostic factors were: the presence of extracranial tumors, pre-treatment performance status, and the lung as a primary site. Patients without extracranial tumors prior to FSRT had a median survival of 21.2 months. For seven patients with high-grade glioma, 1-year actuarial local control rate was 75%, with a median survival of 10.3 months. For patients with skull-base tumors the local control was achieved in 6 of 6 patients (100%), with a median survival of 30.7 months. No one suffered from acute complications, but three patients, two of whom had undergone FSRT as the third course of radiotherapy, developed late radiation injuries.

CONCLUSION

Overall high local control and low morbidity rates suggest that FSRT is an effective and safe modality, even for those with a history of prior irradiation. However, patients with risk factors should be treated with smaller fraction doses.

Fractionated stereotactic radiotherapy: rationale and methods

Stereotactic radiosurgery (SRS) has become a widely accepted technique for the treatment intracranial neoplasms. Combined with modern imaging modalities, SRS has established its efficacy in a variety of indications. From the outset, however, it was recognized that the delivery of a single large dose of radiation was essentially "bad biology made better by good physics." To achieve the accuracy required to compensate for this biological shortcoming, the application of SRS has required that a neurosurgical head frame of some sort be rigidly attached to the patients head. Historically, this prerequisite has, primarily for practical reasons, precluded the delivery of multiple fractions over multiple days. With recent improvements in immobilization and repeat fixation, the good biology of fractionated delivery has been realized. This technique, which has come to be known as stereotactic radiotherapy (SRT), has significantly expanded the efficacy of the technique through the use of accurate physical targeting coupled with the basic radiobiological principles gleaned from decades of clinical experience.

The integral biologically effective dose to predict brain stem toxicity of hypofractionated stereotactic radiotherapy

OBJECTIVE

The aim of this work was to develop a parameter for use during fractionated stereotactic radiotherapy treatment planning to aid in the determination of the appropriate treatment volume and fractionation regimen that will minimize risk of late damage to normal tissue.

MATERIALS & METHODS

We have used the linear quadratic model to assess the biologically effective dose at the periphery of stereotactic radiotherapy treatment volumes that impinge on the brain stem. This paper reports a retrospective study of 77 patients with malignant and benign intracranial lesions, treated between 1987 and 1995, with the dynamic rotation technique in 6 fractions over a period of 2 weeks, to a total dose of 42 Gy prescribed at the 90% isodose surface. From differential dose-volume histograms, we evaluated biologically effective dose-volume histograms and obtained an integral biologically-effective dose (IBED) in each case.

RESULTS

Of the 77 patients in the study, 36 had target volumes positioned so that the brain stem received more than 1% of the prescribed dose, and 4 of these, all treated for meningioma, developed serious late damage involving the brain stem. Other than type of lesion, the only significant variable was the volume of brain stem exposed. An analysis of the IBEDs received by these 36 patients shows evidence of a threshold value for late damage to the brain stem consistent with similar thresholds that have been determined for external beam radiotherapy.

CONCLUSION

We have introduced a new parameter, the IBED, that may be used to represent the fractional effective dose to structures such as the brain stem that are partially irradiated with stereotactic dose distributions. The IBED is easily calculated prior to treatment and may be used to determine appropriate treatment volumes and fractionation regimens minimizing possible toxicity to normal tissue.

Metástase cerebral: tratamento paliativo com radiocirurgia

O artigo faz avaliação de 52 pacientes com metástase cerebral tratados com radiocirurgia estereotática na Universidade McGill, em Montreal. A radiocirurgia foi realizada com a técnica dinâmica em que, ao mesmo tempo, giram a mesa e a cabeça do acelerador linear de 10 MV. Todos os pacientes (56 tratamentos ao todo) foram tratados com um único isocentro e uma dose única mediana de 1800 cGy na periferia da metástase. Em 88% dos casos a radiocirurgia foi usada após falha de tratamento radioterápico fracionado em todo cérebro. Todos os 52 casos tiveram avaliação com CT pós radiocirurgia. O seguimento mediano foi de 6 meses (variou entre 1 e 37 meses) e a taxa de resposta, parcial ou completa, foi de 64%. Apenas 4 pacientes (7%) tiveram algum tipo de complicação tardia relacionada ao tratamento. Estes achados vão de encontro com dados da literatura. A radiocirurgia é tratamento pouco agressivo, bem tolerado e com alta taxa de resposta para lesões locais e pode ser útil para pacientes selecionados. O seu valor definitivo, como tratamento único ou combinado com radioterapia em todo cérebro, está sendo avaliado de forma prospectiva e randomizada.