VIDEO GUIDANCE: Contains scenes of surgery.
Visiting the Royal Marsden Hospital in London, Peter is examining the latest techniques and treatments available in the fight against cancer.
He said he felt "privileged" to speak to the doctors and patients about their experiences.
Breast cancer in particular has been highlighted recently in the media, with Hollywood actress Angelina Jolie revealing she has undergone a double mastectomy in a bid to reduce her risk of getting the disease.
In the first instalment of the cancer diaries Peter spoke with 51-year-old Jackie George who was diagnosed with breast cancer in 2009.
She had a mastectomy in 2010 has returned to hospital for reconstructive surgery.
Speaking about receiving the news she had cancer, she said: "My first reaction was 'I'm not going to see my children have their children'.
"But I think once you've got some information and the support that's available to you, although it doesn't make it go away, it does help you come to terms with (it).
"I'm getting me back. I'm feeling more confident with how I look; I'm going to be more comfortable. It's almost like a conclusion and I can put the breast cancer behind me."