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Giving night owls radiotherapy in the afternoon ‘could reduce side effects’

Afternoon radiotherapy sessions could reduce side effects such as pain, scarring and incontinence for breast and prostate cancer sufferers

  • Radiotherapy causes side effects by damaging healthy tissue near cancer cells 
  • Treatment times could be based on the time of day someone is more active
  • Experts believe the state of the immune system during treatment is important
  • Reducing side effects in this way could be an easy way to improve quality of life 

Giving some cancer patients radiotherapy later in the afternoon could reduce their risk of side effects, researchers have found.

Breast cancer patients who are night owls could be left with fewer painful lumps and scarring, and prostate cancer patients less incontinence, bleeding or diarrhoea.

And scientists say a test could reveal whether someone is a morning or night person and allow doctors to tailor their treatment to suit them.

People genetically inclined to be more active later in the day could suffer fewer side effects if given their treatment after lunch, research found.

Radiotherapy given to cancer patients could produce fewer crippling side effects if it is given to people at a time when they are naturally more active – so in the afternoon for people who are genetically predisposed to be late risers (Stock image of someone having radiotherapy)

A study led by the University of Leicester followed 4,000 patients and tested their blood in a study which successfully predicted the severity of their side effects.

Scientists can test whether someone is a morning or evening person by looking for certain gene variations, known as PER3 and NOCT, The Times reported.

‘We know that patients vary in the way they respond to radiation treatment — but we don’t have a reliable way of identifying these patients,’ said lead researcher Dr Chris Talbot, from the University of Leicester.

‘So radiation doses for all patients are currently limited by the risk of side-effects in the most sensitive patients.

‘This is the largest study to date to assess the use of biomarkers to predict radiotherapy-related toxicity.’


Radiotherapy is a cancer treatment in which radiation is used to destroy tumour cells.

It is most commonly delivered as beams of radiation which are targeted at a tumour and are so powerful that the energy destroys the flesh it is aimed at.

Radiotherapy can also be done by temporarily putting radioactive implants into the body near the cancer, or by swallowing or injecting radioactive medicine.

Because radiation does not distinguish between cancerous and healthy tissue, it can destroy healthy flesh as well.

This can cause side effects such as pain, sickness, tiredness, hair loss and loss of appetite.

Radiotherapy usually takes multiple sessions over a number of weeks, and it can be used to try and cure a tumour or just to relieve symptoms.

Source: NHS

To predict which patients would be worse affected by treatment in the morning, the researchers tested the effect of radiation on samples of their blood.

People who had a lower percentage of white blood cells killed by radiation developed worse side effects over the long term.

This, Dr Talbot suggested, may be because the state of the immune system on treatment day is an important factor in side effects’ development.

Radiotherapy works by targeting powerful, focused radiation beams at cancerous cells in a bid to destroy them.

It is a common cancer therapy and can be used to try and cure the disease, to shrink tumours before surgery or prevent them returning afterwards, or to relieve symptoms if a cancer can’t be cured.

But because radiation is damaging to all living cells, healthy parts of the body can be damaged and destroyed during treatment.

This can lead to side effects which include soreness, fatigue, hair loss, sickness and diarrhoea, according the NHS.

Dr Talbot suggested using a simple test to try and reduce the risk of side effects could improve the quality of life for cancer patients during and after treatment.

He added: ‘If these findings are confirmed, we could avoid side-effects in patients simply by testing for these genes and then advising on the best time of day to be treated.’


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