Kate Middleton shared her cancer diagnosis in an unexpected video statement last night.

The Princess of Wales explained that the news came as a “huge shock” to her and her family.

Kate has spent the last few months out of the public eye, following a planned abdominal surgery which was initially thought not to be cancer-related.

Here’s a look at what is publicly known about her condition at the moment.

When she had planned abdominal surgery on January 16 at a private facility – the London Clinic – Kensington Palace said her condition was “not cancer-related”.

News of the surgery was announced the day after it happened. The Palace only said it was successful, but did not offer any further details.

In Friday’s video, Kate said “tests after the operation found cancer had been present” and she was now in the early stages of preventative chemotherapy.

Dr Yuman Fong, a surgeon at City of Hope cancer centre in Southern California, told Associated Press finding cancer after surgery for a noncancerous problem can happen in about 4% of procedures.

A patient can be going for a surgery related to what is thought to be a benign disease, like removing the gallbladder or ovarian cysts, when cancer can be found, according to Fong.

It is common for tissues taken during surgery to be analysed at a lab afterwards, and that’s when other conditions may be detected.

The NHS says: “Cancer is a condition where cells in a specific part of the body grow and reproduce uncontrollably. The cancerous cells can invade and destroy surrounding healthy tissue, including organs.”

Cancer can sometimes spread through the body, too – that’s known as secondary or metastatic cancer.

One in every two people in the UK will develop cancer in their lifetime.

There are more than 200 different types, and each one is diagnosed and treated differently.

Anyone can get cancer but the risk increases as people get older – more cases are found in people aged 50 and over – because there’s more time for cell damage to accumulate.

But, rates of cancer diagnosis are rising for younger people in developed countries, according to medical research. Kate is 42.

Dr Fong told AP: “We hate it when young people get cancer but at the same time, they are the ones that recover best.”

Survival rates from cancer have doubled over the last 50 years, according to Cancer Research UK.

There’s a huge variation in survival between cancer types. Fifty per cent survive cancer for 10 or more years, according to Cancer Research’s data from 2010-11.

Kate did not reveal this, and neither did the Palace.

It’s unlikely they will any time soon, especially as the Princess of Wales has already shared an unprecedented amount of detail about her health.

A Kensington Palace spokesperson said: “We will not be sharing any further private medical information. The princess has a right to medical privacy as we all do.”

Kate said in her statement her team advised her to start ‘preventative chemotherapy’ in late February.

She is now in the early stages of this treatment.

Chemotherapy is an un umbrella term for medication – administered by drip or via pill – meant to kill cancerous cells.

It’s meant to stop the risk of cancer coming back again, although the amount needed and how regularly it needs to administered depends on the cancer.

According to the NHS website, chemo can cause some difficult side effects, though “many can be treated or prevented and most will pass once your treatment stops”.

Not everyone gets the same side effects, but some common ones include: anaemia, infections, loss of appetite, fatigue, nausea and hair loss.

Dr Monica Avila of Moffitt Cancer Center in Tampa, Florida, told AP: “A patient can take anywhere from a few weeks to a month or two to recover from those effects.”

The Palace did not reveal a working timeline for Kate’s treatment, or the advice from her medical team who will decide when it is.

But, the royal officials seem confident Kate will recover.

The statement said: “The Princess is now on a recovery pathway.”

In her video statement, Kate said she had taken her time to tell the public her diagnosis because she wanted to first reassure her three children – aged 10 and under – that she was “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,” Kate said.

King Charles’s spokesperson expressed the monarch’s pride for his daughter-in-law Kate Middleton after she revealed her cancer diagnosis last night.

Buckingham Palace said the King is “so proud of Catherine for her courage in speaking as she did”.

The pair have “remained in the closest contact with his beloved daughter-in-law throughout the past weeks” after they spent time in hospital together, according to the spokesperson.

They added that Charles and his wife, Camilla, “will continue to offer their love and support to the whole family through this difficult time”.

In a video statement released on Friday, Princess of Wales announced she was diagnosed with cancer after a planned abdominal surgery in January.

She said she is now undergoing preventative chemotherapy.

The news comes a few weeks after the monarch revealed he was diagnosed with cancer earlier this year following a separate procedure for a benign prostate enlargement.

Charles is now going through a schedule of regular treatments.

The two royals were treated at the London Clinic at the same time earlier this year.

The Palace has not revealed what kind of cancer either of the senior royals has, and it is unlikely to do so.

Prince Harry and Meghan Markle extended their sympathies to Kate from across the pond, saying: “We wish health and healing for Kate and the family, and hope they are able to do so privately and in peace.”

Kate’s brother James Middleton also posted on Instagram about the news, sharing an old photo of the two of them alongside the caption: “Over the years, we have climbed many mountains together. As a family, we will climb this one with you, too.”