Boosting the dose: new approaches needed

French researchers have investigated whether a selective radiotherapy dose increase to tumour areas with significant uptake of 18F-FMISO – a PET radiotracer used to diagnose hypoxia – could improve outcomes in patients with non-small cell lung cancer (NSCLC). The study, conducted by 15 academic PET facilities across France, evaluated 54 patients with localized, advanced non-small cell cancers, who were undergoing chemoradiotherapy. For each patient, they performed two FDG-PET/CT and two FMISO-PET/CT scans using the same machine and identical operational conditions. Quality control was centrally supervised to ensure homogeneity in the image quality in all participating centres (J. Nucl. Med. 58 1045).

In 24 patients, the radiotherapy dose could be increased up to 86 Gy on FMISO-identified hypoxic areas. This dose increase did not improve patient outcomes, however, with FMISO uptake strongly associated with poor prognosis. Pierre Vera of the Henri Becquerel Cancer Center and Rouen University Hospital noted: "We demonstrated that this approach of radiotherapy boost based on hypoxia PET is feasible in a multicentre setting. Regarding the clinical aspect, a recent randomized trial failed to demonstrate the benefit of escalated radiotherapy dose in large target volumes. Our data show that smaller volumes, identified on their functional characteristics using hypoxia PET/CT, can be adequately targeted. In addition, no significant toxicity has been observed in patients receiving radiotherapy boost."

Radiotherapy alters neural networks

Radiation therapy plays a vital role in treating brain tumours, but is also associated with adverse effects such as neuronal loss in adjacent healthy tissues. Previous research has shown that radiotherapy can affect discrete brain regions by causing cortical atrophy. Now, researchers at UC San Diego have used complex mathematical models such as graph theory to analyse MRI-derived cortical thickness estimates in 54 brain tumour patients, before and after radiotherapy. They found that irradiation produced both local and global changes in the structural network topology of the brain, thinning the cortex at a rate faster than that associated with Alzheimer's disease, and increasing segregation between regions of the brain that typically work together to perform functions such as memory-making and recall (Brain Connectivity 7 299).

"Radiotherapy is a mainstay of brain tumour treatment," said first author Naeim Bahrami. "Unfortunately, a side-effect can be incidental irradiation of normal brain tissue and radiation-induced injury, which have been linked to impairment of brain function. As patient outcomes improve, a major concern is managing long-term complications, including cognitive decline and disability." Bahrami notes that more research is needed to determine whether the topology-based technique might be useful in predicting or monitoring neurocognitive decline in patients following radiotherapy or other cancer-related therapies. "Finding a non-invasive imaging biomarker to better assess cognitive function in the moment and in the future would be very helpful to clinicians," he said.

Radiosurgery proves favourable for trigeminal neuralgia

A study from Cleveland Clinic has shown that stereotactic radiosurgery is an effective treatment for patients with trigeminal neuralgia (TN), a painful nerve disorder that causes an electrical shock feeling in the face. TN is commonly treated with anti-epileptic medications. While this can reduce the pain, it makes patients drowsy and tired and frequently causes depression, as it can preclude driving, working or even leaving the house. This latest study revealed that radiosurgery, which is usually a second-line treatment after medication, helps improve quality-of-life and reduce depression. The authors note that considering radiosurgery earlier as a treatment option could help improve the lives of TN patients more quickly (Int. J. Rad. Oncol. Biol. Phys. doi: 10.1016/j.ijrobp.2017.04.008).

The Cleveland Clinic researchers collected data from 50 patients with TN treated using radiosurgery. They asked questions about the patients' pain and facial numbness, their health and ability to take care of themselves. Analysis of answers before and after treatment revealed that patients reported an improved quality-of-life and lower rates of depression after radiosurgery. "We knew radiosurgery results in pain relief, but we didn't know if the patients actually felt better," said corresponding author Samuel Chao. "I think people go and see their neurologist and get the pain under control with medication, but they don't realize how lousy this can make them feel. Using radiosurgery earlier on allows patients to get off the medications, improving their quality-of-life by allowing them to return to activities they used to do."

SIRT shows advantage for right-sided colorectal tumours

For patients with colorectal cancer that has metastasized to the liver, having a primary tumour on the left side, as opposed to the right side of the colon, is known to be a significant advantage in terms of treatment response. A study presented at the ESMO 19th World Congress on Gastrointestinal Cancer suggests that this imbalance could be at least partially redressed. Reversing the usual pattern, patients whose liver metastases had spread from right-sided primary tumours (RSP) had a 36% better survival rate after treatment with first-line chemotherapy plus selective internal radiation therapy (SIRT) using Y-90 resin microspheres, compared with chemotherapy alone. In patients with left-sided primary tumours (LSP), this same combination was no better than chemotherapy alone.

The international research team analysed 739 patients – 24% with RSP and 73% LSP – from two completed studies, who had been randomized to receive chemotherapy, either alone or combined with SIRT. Overall, outcomes were not different between the two treatment groups. However, RSP patients with liver metastases had significantly better overall survival when SIRT was added to their chemotherapy (22.0 versus 17.1 months). This was not the case for patients with LSP (24.6 versus 25.6 months). "These findings are good news for patients with right-sided primary tumours, who have a much worse prognosis and fewer treatment options than patients with left-sided tumours," explained study investigator Guy van Hazel from the University of Western Australia.

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