For Dr Tess McPherson, the day she found out she was pregnant with her third child should have been one of the happiest of her life.

But just hours earlier, the 38-year-old had received some of the worst news she could have imagined. She found out she had breast cancer.

Dr McPherson, from Summertown, Oxford, who is a dermatology specialist at the Churchill Hospital, in Headington, discovered a small lump in her breast and was diagnosed with cancer in November, 2005.

The former Cherwell School pupil then had to make the agonising decision about whether to continue with the pregnancy.

Dr McPherson said: “My doctor said there was no extra risk to me and as time went on, my pregnancy seemed to be going OK.

“She was so nice and so calm and said to me there’s no reason not to be positive.

“It was hard to think about having a third child, while at the same time thinking I have got to make sure I’m still here for everyone else. But it felt good to know there was something healthy and thriving in my body, while everything else was being destroyed.”

Dr McPherson, who underwent a double mastectomy while still pregnant, went on to have a healthy daughter, Alma, who will be four in June. Because her cancer was linked to hormones, Dr McPherson also had her ovaries removed, and underwent chemotherapy and breast reconstruction surgery.

She is taking part in Cancer Research UK’s 5km Race For Life in London as a celebration of her own successful battle against the cancer which also affected her mother and grandmother.

She added: “If you have cancer you are never fully safe again.

“But we are in a positive place. I feel very lucky I had such great treatment and a child I didn’t expect to have.”

Dr McPherson has taken part in Race for Life with her ten-year-old daughter Josie every year since being diagnosed.

With the help of husband, James, and eight-year-old son Sonny the family has raised more than £7,000 over the past three years for Cancer Research UK.

Dr McPherson added: “Alma did it for the first time last year. I had to carry her, but this year she is going to walk. My mother and sister and a group of friends always come along and we take a picnic along and make a day of it.

“Taking part makes me feel full of hope. It keeps me strong.

“I won’t be racing around because it will be over too quickly. I want to soak it up.

“I feel so lucky to have had the treatment I received and that is thanks to charities like Cancer Research UK.

“Everyone has a story to tell about their own experience, that’s what brings us all together. And if sharing my story helps other people, I am happy.”

Oxford’s Race for Life is at the University Parks on June 5 and 6. To take part, go call 0871 641 1111.