The radiation evolution improving cancer treatment

by North & South / 11 September, 2017

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Advances in radiotherapy are cutting cancer treatment times dramatically and improving outcomes.

Radiotherapy has long been a key treatment in the fight against cancer. And while the basic principles are the same – using X-rays to destroy cancer cells at a DNA level and stop them from reproducing – the technology has come a long way and is evolving apace.

“The radiation that we give now, compared to just five to 10 years ago, has changed dramatically,” says radiation oncologist Dr Louis Lao, who works at Auckland City Hospital and Auckland Radiation Oncology.

Two areas of advancement have changed the face of radiotherapy: better imaging and more precise targeting. Image guidance radiotherapy, which maps out the treatment area along with image guidance on the actual treatment machine, allows experts to accurately target tumours and therefore greatly reduce toxicity to surrounding areas. And because of the improved accuracy, cancer cells can be treated to higher doses and treatment times can be cut.

The imaging is achieved using state-of-the-art technology. Data from planning CT is loaded onto software to create a precise map of the tumour, using information from MRI or PET scans. A cone beam CT is obtained in the treatment room to allow image guidance, moving around the patient to produce many images. Patients can then be repositioned to ensure accuracy and precision.

“The beauty about adaptive radiotherapy is we’re now getting feedback as to how the cancer is reacting while the patient is undergoing treatment,” says Dr Lao. “In the past we would deliver, say, a six-week treatment programme and then do a scan to see how things were going. Now we’re seeing what’s happening every day so we have the opportunity to make adjustments and improve outcomes.”

The introduction of stereotactic ablative radiotherapy allows the delivery of a high dose to the tumour over a very short time with low risk of toxicity. The accuracy is afforded by the use of shielding devices called multi-leaf collimators on a linear accelerator machine, which can be positioned in various ways to shape the pre-mapped radiation field. These shielding devices can be tuned to sub-millimetre accuracy.

The wins are phenomenal – for patient experience, potential outcomes and use of resources. For early-stage lung cancer, for example, the conventional plan was 30 treatments over six weeks. This has been reduced to between three and eight treatments over about a week and a half. The traditional course for breast cancer was five weeks – now it is routinely reduced to three weeks.

Sovereign CEO Nick Stanhope says it’s an exciting time for insurers looking to tap into the latest medical treatments on behalf of customers. “We partner with a diverse range of radiation specialists and try to keep at the forefront of advancements that encourage a speedy, professional and effective treatment journey for our customers,” he says. “If the power of advanced radiation therapy can fast-track their recovery, that’s a clear bonus.”

The emerging trend to give bigger doses each treatment and reduce the treatment time is called hypofractionated radiation. “But we’ve got to make sure we achieve the same or improved efficacy in terms of controlling the cancer, and that we’re not introducing more toxicity by shortening treatment times,” cautions Dr Lao. “We need research data to make sure it’s safe.”

That data comes from clinical studies and as results roll in, reduced treatment times are gaining traction. Risks and side-effects have been minimised by the new technology, mainly due to reduced toxicity to normal tissue, achieved by the more precise targeting. It is the radiation “splash” of the past (treating a wide field so that normal tissue is treated along with cancer cells) that caused side-effects ranging from fatigue and nausea to organ damage. Skin burn (radiation dermatitis) is largely a thing of the past because of the new accuracy. Tumours tend to be deep-seated and doctors can ensure that surface skin gets only a very low dose. The exception is skin cancer where skin is the target, but even here, there’s less toxicity due to the reduced treatment field.

All in all, it’s an exciting and fast-changing area with accuracy of delivery and dose modulation under constant review, along with up-and-coming developments such as MRI-guided treatment, radiation used in combination with drug therapy to drive the immune response, and – overseas for now – even using different types of radiation such as protons and carbon-iron.

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