Chemically enhanced radiotherapy: visions for the future.

Radiotherapy (RT) is an important part of cancer management, with more than a third of all cancer cures being attributable to RT. Despite the advances in RT over the past century, the overall outcomes in a majority of malignancies are still unsatisfactory. There has been a constant endeavor to enhance the outcome of RT, and this has been in the form of altered fractionation, oxymimetic radiosensitizers, the use of concurrent chemotherapy, anti-angiogenic therapy and anti-growth factor receptor targeted therapies. This article presents a vision for the future, with emphasis upon emerging prospects which could enhance RT outcomes. Positive speculations regarding the use of immunological aspects, the use of nanoscale technology and the adoption of metronomic concurrent chemotherapy have been presented. Also, the potential with the use of low dose hyperradiosensitivity in enhancing chemotherapy outcomes too has been discussed. In this era of evidence based clinical practise, there exists a strong obsession towards the 'present' with 'contempt towards the future'. Accepting the shortcomings of the existing modalities, there must be a strong zeal towards discovering better methodologies to enhance radiotherapeutic outcomes for the sake of a better future.

Radiotherapy to volumes defined by metabolic imaging in gliomas: time to abandon monstrous margins?

The survival in patients with high grade gliomas (HGG) remains poor even after the adoption post-operative radiotherapy (RT) to magnetic resonance imaging (MRI) based volumes. Despite delivery of 'standardized' doses of radiation, recurrence is the norm, rather than the exception. Recurrences occur both within, and outside of the volume of irradiation, leading us to two questions-firstly concerning the adequacy of the dose of radiation used, and secondly about the current methods of treatment volume delineation. The emergence of newer radiopharmaceuticals for use in positron emission tomography (PET) have kindled the hope of more precise volume localizations for post-operative RT, and it is likely that these new radiopharmaceuticals can help us define accurate areas at highest risk of recurrence and thus allow us to use increased doses of radiation with confidence.

Re-irradiation with hypo-fractionated stereotactic robotic radiotherapy for salvage in adult patients with brainstem glioma.

PURPOSE: Brainstem glioma (BSG) is often treated with definitive irradiation. However, subsequent progression and death occur as a rule rather than the exception, after varying periods of control. The outlook of patients with post-irradiation progression is dismal, and most of these patients are treated with supportive care alone. Despite the obvious risks with an area as critical as the brainstem, it is a possibility to encounter situations wherein the patients (themselves or their associates) ask for re-irradiation, with the hope of a few extra months of life. The risk of radiation-induced brainstem toxicity may be justifiable under the strict assumption that the patients stand a chance of benefiting from re-irradiation but still may not live long enough to manifest brainstem toxicity. METHODS: Five adult BSG patients were treated with re-irradiation using robotic-arm stereotactic radiation therapy (SRT) between September 2009 and July 2012, primarily at the request of the concerned patient parties. Re-irradiation doses ranged from 16 to 25 Gray (Gy) delivered by robotic arm stereotactic irradiation in 2-5 fractions. RESULTS: Four out of five patients enjoyed a prolongation of survival in the order of months (three, five, six, and 14 months), which was very significant given that all patients had severe neurological compromise and poor performance status prior to re-irradiation. One patient has survived 36 months after re-irradiation and thus has lived long enough to manifest late radiation-induced brainstem toxicity. CONCLUSION: Despite the obvious risks of brainstem toxicity associated with the use of re-irradiation for BSG, the use of fractionated stereotactic re-irradiation seems to offers prospects of additional periods of local control and augments duration of life.

The demonstration of extension of high-grade glioma beyond magnetic resonance imaging defined edema by the use of (11) C-methionine positron emission tomography.

The use of magnetic resonance imaging (MRI) is the current standard for the delineation of target volumes for high-grade gliomas (HGG). While the peritumoral edema as per T2-weighted (T2W) imaging is utilized as basis to delineate the initial borders of the clinical target volume (CTV), those areas enhancing on T1-weighted (T1W) images with gadolinium contrast (T1-Gd) are considered for treatment with further boost. However, recent data has emerged concerning the use of positron emission tomography (PET) with 11 C-methionine, which seemingly provides additional information beyond MRI. We present the case of a gentleman with an inoperable HGG which was imaged with 11 C-methionine-PET ( 11 C-MET-PET)/CT as well as MRI as part of the radiotherapy treatment planning (RTP) process. The differences noted between the MRI and the PET defined volumes are presented. This being a patient who was not operated, the potentially confounding issue of surgery-induced PET-avidity is absent.

PET/CT-guided percutaneous biopsy of isolated intramuscular metastases from postcricoid cancer.

(18)F-FDG PET/CT has made it possible to identify many unsuspected lesions such as isolated intramuscular metastases because of its ability to detect abnormal metabolic activity in an early stage even without clinical symptoms or morphologic changes. We need to modify our routine techniques for performing biopsies of such lesions because they may not be visualized on morphologic imaging. We describe a technique in which fused PET/CT is used to guide the percutaneous biopsy needle for sampling isolated intramuscular metastatic lesions in a patient whose intramuscular metastases were identified only on PET/CT, not on CT or ultrasound, and were clinically occult.