Why Kate Middleton is getting preventative chemotherapy: What next for the Princess's cancer recovery and the side effects of the intense treatment she will be undergoing

Kate Middleton shocked the world by announcing she has cancer in a deeply personal and emotional televised statement.

The Princess of Wales, 42, announced she is undergoing 'preventative chemotherapy', with her disease being spotted after major abdominal surgery in January.  

But what is preventative chemotherapy? When is it used? Is it the same as traditional chemo? And what are the side effects?

Discovering cancer after an operation is 'not uncommon', a top doctor has said.

Dr Mangesh Thorat, deputy director of the Barts clinical trials unit at the centre for cancer prevention at Queen Mary university, told Sky News: 'It is not very common, but it's not uncommon either.

'We often find this because the scans we do pre-operatively often have their limitations. When things are looked under the microscope, after an organ is taken away, you get a much better resolution and then you pick up the cancer.

'So it's not uncommon.'

Here, MailOnline explains all…

What treatment is Kate getting?

In her emotional statement filmed at Windsor, Kate said her medical team 'advised that I should undergo a course of preventative chemotherapy'.

She revealed she was in the 'early stages of that treatment', which began in late February.

Kate is now said to be in a 'recovery pathway'. No other details were given.

Chemotherapy uses powerful drugs to attack tumours and is typically given to treat cancer directly or shrink a tumour in preparation for surgery.

As in Kate's case, chemo can also be used as a preventative option in the hope of stopping cancer coming back.

Diagram showing how preventative chemotherapy works

Does this mean her cancer has already gone?

No details were shared as to whether this was the case.

Kate only shared that her major abdominal surgery in London in January, for what doctors thought was a non-cancerous condition before learning the truth, was successful.

Preventative chemotherapy, also called adjuvant chemotherapy, aims to stop cancer coming back once the main tumour has been removed from the body.

The NHS says it can be used to 'reduce the risk of the cancer coming back after radiotherapy or surgery'.

What does the treatment entail?

Preventative chemotherapy is most often delivered as an IV drip or tablets where they are then carried throughout the body by the bloodstream.

Depending on the type, chemotherapy can be administered in either a hospital or in the comfort of a patient's home.

There are over 100 types of chemotherapy drugs.

All work in a similar way, circulating through the blood to stop cancerous cells anywhere in the body reproducing by killing them before they get chance to divide. This prevents them from growing and spreading in the body.

What are the side effects?

Cancer Research UK says: 'The fact that chemotherapy drugs kill dividing cells helps to explain why chemotherapy causes side effects.

'Body tissues are made of billions of individual cells.

'Once we are fully grown, most of the body's cells don't divide and multiply much. They only divide if they need to repair damage.'

However, some cells still do divide in fully grown adults, like ones found in hair (which is constantly growing) and skin (which renews itself all the time).

Because the treatment indiscriminately affects body tissues, regardless of whether they are cancerous or not, it can trigger side effects like hair loss, fatigue and bruising.

Often a patient undergoing chemotherapy also takes other medication designed to help mitigate or combat some of these symptoms.

Symptoms typically disappear when the course of treatment finishes.

The Princess of Wales said her family (pictured together on December 25) 'need some time, space and privacy while I complete my treatment'

What the NHS has said?

NHS chief executive, Amanda Pritchard, said: 'On behalf of the NHS, I'm really sorry to hear this shocking news.

'Our thoughts are with the Princess of Wales and the Royal Family, especially while her treatment continues.

'We know how difficult a diagnosis and treatment journey can be for patients and their families.

'Speaking out about it is really brave and it can help others to get worrying signs and symptoms checked.

'If you're worried about cancer, the NHS website has more information.'

How have other cancer charities reacted?  

Charities have praised Kate's decision to speak out, saying it will encourage others to seek help for their own potential cancer symptoms.

Cancer Research UK's chief executive, Michelle Mitchell, said: 'On behalf of everyone at Cancer Research UK, I wish Her Royal Highness a full, swift recovery and return to good health.

'During this difficult time, it's important that the Princess is given the time and space to focus on her treatment and that we respect the family's privacy.'

She added: 'High profile cancer cases often act as a prompt to encourage people to find out more or think about their own health.

'If people spot something that's not normal for them or isn't going away, they should check with their GP.

'It probably won't be cancer. But if it is, spotting it at an early stage means treatment is more likely to be successful.'

Kate's cancer battle in her own words: The Princess of Wales' emotional video statement in full 

I wanted to take this opportunity to say thank you, personally, for all the wonderful messages of support and for your understanding whilst I have been recovering from surgery.

It has been an incredibly tough couple of months for our entire family, but I've had a fantastic medical team who have taken great care of me, for which I am so grateful.

In January, I underwent major abdominal surgery in London and at the time, it was thought that my condition was non-cancerous. The surgery was successful. However, tests after the operation found cancer had been present. My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment.

This of course came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family.

As you can imagine, this has taken time. It has taken me time to recover from major surgery in order to start my treatment. But, most importantly, it has taken us time to explain everything to

George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be ok.

As I have said to them; I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits.

Having William by my side is a great source of comfort and reassurance too. As is the love, support and kindness that has been shown by so many of you. It means so much to us both.

We hope that you will understand that, as a family, we now need some time, space and privacy while I complete my treatment. My work has always brought me a deep sense of joy and I look forward to being back when I am able, but for now I must focus on making a full recovery.

At this time, I am also thinking of all those whose lives have been affected by cancer. For everyone facing this disease, in whatever form, please do not lose faith or hope. You are not alone.