The fifth annual Marsden March from Chelsea to Sutton is taking place today in support of the Royal Marsden Cancer Charity.
Comedian Tim Vine is one of the celebrities supporting this year's fundraiser - he'll be at King George Playing Fields to cheer on walkers.
Participants are being sponsored to do a 14-mile or five-mile walk taking place to raise money for The Royal Marsden Cancer Charity.
The Duke of Cambridge has hailed the "incredible" workof two surgical teams as he watched live operations at one the Royal Marsden in Chelsea.
Dressed in medical scrubs, he spent around 10 minutes viewing a breast reconstruction procedure for a female patient in her 80s.
As he was greeted by lead surgeon, Mr James, William said: "It's slightly surreal meeting you in this situation."
The Duke looked into a micro-vascular microscope placed above the body as he was talked through the surgical procedure, which usually takes six to eight hours to complete.
"That's amazing," he said as he peered through the microscope.
William is the first royal to view surgery at the Royal Marsden,which is a world-leading cancer centre specialising in all areas of diagnosis,treatment, care and research into the disease.
He has been president of the hospital trust since 2007, a position previously held by Diana from 1989 until her death in 1997.
The Duke of Cambridge will watch two live operations today at the Royal Marsden in Chelsea, west London, where he will view sections of a breast reconstruction procedure and the removal of a bladder tumour.
He is set to meet members of the surgical team involved in the operations in the Wolfson Surgical Suite, including the lead surgeons, Mr Stuart James and Mr Pardeep Kumar.
The Duke will be following in the footsteps of his mother, Diana, Princess of Wales, after she watched a heart operation at Harefield Hospital in Middlesex in 1996.
He will be the first royal to view surgery at the Royal Marsden, which is a world-leading cancer centre specialising in all areas of diagnosis, treatment, care and research into the disease.
The Duke of Cambridge will watch two live surgeries at The Royal Marsden NHS Foundation Trust in Chelsea today.
Prince William will visit The Wolfson Surgical Suite where he will view sections of a breast reconstruction and the removal of a bladder tumour.
He will then meet members of The Royal Marsden's surgical team involved in the operations, including the lead surgeons, Mr Stuart James and Mr Pardeep Kumar.
A coroner has said a toddler died because of a series of failures at three London hospitals. Two year old Alice Mason survived surgery to remove a brain tumour but weeks later doctors failed to diagnose fluid on the brain.
Recording a narrative verdict, the coroner said consultants at Kingston, Royal Marsden and St George's hospital had failed in their leadership and that Alice's death was avoidable.
The coroner made a regulation 28 report to NHS London with a copy to the Care Quality Commission outlining a "risk of future death" unless concerns about practices were addressed.
Drew Lindon, from Prostate Cancer UK has told ITV London that the introduction of a new prostate cancer drug was vital as it could help to prolong life for a "few extra months to spend with love ones".
Improving the quality of life for men with prostate cancer is the goal of a treatment being pioneered by London hospitals.
Prostate cancer kills four men every day in the capital, and this new approach - a daily tablet - is said to avoid the worst side-effects of current treatments.
Clare Fernyhough reports:
Prostate Cancer UK has welcomed the news of a new drug that offers hope to men who have run out of treatment options, but urged other areas of the UK to appraise the drug swiftly.
Drew Lindon, from the charity said: "For some men, this drug could offer precious extra time with loved ones, and will be a welcome addition to what is currently a very limited armoury.
"However, although enzalutamide can now be prescribed by doctors, a man's local NHS health provider is not obliged to pay for it.
"And while men in England can apply for access through the Cancer Drugs Fund, others living elsewhere in the UK could be left at a disadvantage.
"We urge National Institute for Health and Clinical Excellence and Scottish Medicines Consortium to appraise this drug swiftly, and the pharmaceutical company to set a reasonable price, in the hope that it will soon be recommended and routinely available on the NHS for all those men who need it."
Managing the side effects of cancer treatment is one of the biggest challenges in medicine, a consultant oncologist at University College London Hospitals said today, after the launch of a new drug with less side effects.
Dr Heather Payne said:
A new hi-tech prostate cancer drug has already demonstrated a 'positive impact on the quality of life', the Institute of Cancer Research said today, as the treatment trials in the capital.
Professor Johann de Bono from the institute, who led the Affirm trial, said:
"Enzalutamide is a much needed development in prostate cancer treatment and will provide a new option for the increasing number of men with advanced prostate cancer in the UK whose disease has become resistant to first-line hormonal treatments and who have had docetaxel chemotherapy.
"Enzalutamide has already demonstrated a positive impact on quality of life whilst increasing the life-span of patients with this common disease.
"It's use will bring significant benefits, establishing it as a key component of advanced prostate cancer treatment in the UK."