The actress, who plays Mo Harris on the programme, told The Sun that she was initially too afraid to get the lump checked.
Morse said: "Wendy rang and asked if I'd been to the doctors. I told her I had and she asked me what they'd said.
"I told her it was just a mammary gland and nothing to worry about. It was a lie. I hadn't been. I knew from the tone of her voice that Wendy didn't believe me."
She added that when she was later having a blood pressure check she could not get Richard's words out her head and told the doctor about the lump.
Morse was diagnosed with cancer and had a the lump removed as further treatment. Her disease eventually went into full remission.
"If it hadn't been for Wendy, more than likely I wouldn't have done anything. It's thanks to her I'm here. I would have just brushed it off but she wouldn't let me," Morse added.
Richard died last month at the age of 65 from a third bout of aggressive breast cancer.