That is an interesting segment. I have been doing a bit of reading about this found this article explaining that there has been limited research in this area, largely because it is difficult to properly study people who have refused some or all conventional treatment. However, they have done some analysis and found much greater risk of death, particularly from breast cancer, if conventional treatments are not followed. I think this may be the article the oncologist refers to in the segment. I have just finished chemo, and have radiation and herceptin to go. While it hasn't been a walk in the park, my prognosis would not have been good if I had not chosen conventional treatment. I had an aggressive grade three triple positive tumour and my life is the most important thing I have.
https://academic.oup.com/jnci/article/110/1/121/4064136This is a good summary of the article:
https://yaledailynews.com/blog/2017/09/05/study-problematizes-alternative-cancer-treatments/