When we first met in May this year, Madam Doan, 38, came in a wheelchair accompanied by several family members from Vietnam.
I could see only her eyes as she covered her head with a cap pulled down low and a face mask that concealed the lower half of her face. She also had a scarf wrapped around her neck and the front of her chest.
Although she spoke Mandarin, I could barely hear her as the words were soft and muffled.
But I managed to extract most of her medical history from the scanty medical records and from those who accompanied her.
Cancer is the uncontrolled and meaningless growth of cells, so there is very little I have not seen in physical anomalies - from flesh transformed by gangrene to rotting breasts and displaced organs from aggressive tumours.
Despite her five-year battle with cancer, Madam Doan was not ready to give up. She simply refused to accept that not having any active treatment was her best option. She was determined to be treated for the oral cancer.
Nonetheless, when it was time for me to examine Madam Doan, I had the shock of my life when she took off her face mask.
There was a large fleshy tumour growing from the floor of her mouth, occupying the oral cavity and protruding out of her mouth.
Like an animal trying to escape from her mouth, the cancer had grown so big that it pushed her lower lip down below her chin.
In addition, there was an even larger tumour, bone-hard and the size of a large grapefruit, in front of the left collarbone.
The disease was causing her a great deal of pain and discomfort. Worst of all, she could not close her mouth and therefore could not eat. Even a liquid diet was difficult to consume because it would dribble out of her partially opened mouth.
After examining her, I was convinced of the futility of further chemotherapy.
I explained to her that her cancer was highly unlikely to respond to any treatment. I suggested that she has a feeding tube inserted through her nose into her stomach and to return home to Vietnam for supportive care.
I also advised generous use of morphine for pain control.
But Madam Doan thought differently. Despite her five-year battle with cancer, she was not ready to give up. She simply refused to accept that not having any active treatment was her best option. She was determined to be treated for the oral cancer.
After much deliberation, we decided to treat her with weekly chemotherapy for six weeks.
She agreed that if she did not get better by the end of six weeks, then she would go back to Vietnam to spend what time she had left with her family. She also agreed to have photographs taken weekly, so that we could determine whether the tumour in her mouth was responding or not.
She was given an improvised concoction of two chemotherapy drugs together with bevacizumab, a monoclonal antibody which works by cutting off the blood supply to the cancer.
After one week, she claimed that the oral cancer was getting better.
I was sceptical.
In the fourth week, she walked into my room without a face mask, beaming from ear to ear, with her mouth closed and lips meeting.
By the end of the sixth week, the mouth tumour had disappeared.
However, the large tumour in front of her collar bone remained unchanged in size. She still has cancer and her prognosis is bleak. But this did not seem to bother her as she was able to talk, eat and show her face unabashedly.
Viewing her collection of "before and after" photos, it was clear that her tenacity in fighting the cancer to the bitter end gave her a much improved quality of life, for whatever time she has left.
Sometimes, the patient does know best.
• Dr Ang Peng Tiam, medical director of Parkway Cancer Centre, has been treating cancer patients for 27 years.