Judy Danchura and the cat, named Sumo, which she credits with saving her life. (CBC)When Judy Danchura opened her door last summer to a hungry stray cat in Winnipeg, that simple act of kindness became a turning point in her life and the start of a battle with cancer.

Danchura found the feline in her backyard one day last June and put out some food. The cat was back at her door meowing loudly enough to wake her at 3 a.m. She let it in, prepared a litter tray, and went back to bed.

While she and her husband slept, the cat hopped onto the bed and walked across her body. As it stepped on her breast, Danchura was struck by an unusual shot of pain.

That's when she noticed a lump.

"I sort of went, 'Oh geez, there's definitely something wrong there,'" she said.

Sumo the cat went from stray to hero by finding a cancerous tumour in Judy Danchura's breast. (CBC)She made a doctor's appointment, which turned into a series of tests and the diagnosis of cancer.

Because the malignant tumour was detected early, and because she was able to start treatment quickly, Danchura's chance of survival is estimated at 95 per cent.

She credits the cat, which she has adopted, with saving her life.

"I don't know what my chances of survival would have been without him," she said. "I know I'd certainly be far worse off."

Danchura named the cat Sumo but likes to refer to him as her "furry four-footed angel."

"I sometimes feel overwhelmed because I feel humbled," she said. "I can't understand why this animal turned up for me."