The core value of the medical culture is: Doctors must have a clear conscience. A Canadian statistician conducted a survey among hundreds of oncologists. One question that was asked is: If you are diagnosed with cancer, would you undergo chemotherapy? More than 70% of the doctors answered “No.” An oncologist from a major hospital told me that if any of his relatives or good friends suffered from cancer, he would be reluctant to give them chemotherapy.
As mentioned earlier, we do not advocate the abolition of chemotherapy but not to use it blindly on whatever types and stages of cancer. It has been reported online that Professor Tang Zhaoyou, a leading cancer expert and a fellow member of the Chinese Academy of Physicians once said, “For some patients, radiotherapy and chemotherapy can lead to aggravation of malignancy of cancer, induce new tumours and more likely to stimulate cancer metastasis.”
A Major Discovery by Professor Tang
The following report was by Chen Feng, Huang Jinjuan and Chen JunNanfang, the correspondence of the Nanfang Daily News:
Guangdong Medical Research has a major breakthrough! Recently, Professor Zeng Yixin, the Director of Sun Yatsen University Cancer Centre, and his research team published an article on “A new origin of cancer stem cells” in the authoritative "Journal of Biological Chemistry" in the United States. It has been confirmed by experiments that ordinary cancer cells can transform to cancer stem cells which lead to the recurrence of cancer. The result of the study will have an important impact on strategies for cancer treatment.
Professor Zeng Yixin explained that the existence of cancer stem cells is considered the source for cancer occurrence and cancer recurrence. In treatment of cancer by radiotherapy and chemotherapy, ordinary cancer cells which are sensitive to radiotherapy and chemotherapy can be easily eliminated. However, cancer stem cells have strong tolerance and are not easily destroyed. These cancer stem cells, like "seed cells", will continue to produce new cancer cells.
On the origin of cancer stem cells, academicians generally agree that cancer stem cells are derived from the malignant transformation of adult stem cells. In 2004, Professor Zeng first proposed that an important characteristic of cancer cells is genomic instability; cancer cells with similar stem cell phenotype can tolerate chemotherapy and radiotherapy and become seeds of recurrence and metastasis. He believes that treatment of damaged DNA will aggravate the genomic instability and increase the possibility of formation of cancer stem cells. He believes that stem cells formed as a result of the malignant transformation of tissue stem cells can be called cancer stem cells while those cells formed by the genomic instability of ordinary cancer cells can be called stem cell-like cancer cells.
In recent years, the research team led by Professor Zeng has conducted some in-depth studies. First, they discovered the existence of stem cell-like cancer cells in nasopharyngeal carcinoma which has very powerful growth feature and strong resistance to radiotherapy and chemotherapy. (Published in the Cancer Research Journal, USA, 2006). A series of studies show that damage of DNA caused by genomic instability can absolutely lead to the transformation of ordinary cancer cells into stem cell-like cancer cells. In chemotherapy, DNA damage agents can, on one hand, eliminate cancer cells, but on the other hand, it can increase the genomic instability and induce the evolution of ordinary cancer cells into stem cell-like cancer cells.
Professor Zeng pointed out that if this doctrine ultimately gets more experimental evidence, then cancer treatment strategies must be changed accordingly. For example, in cancer treatment, we should pay attention to maintaining, as far as possible, genomic stability to prevent ordinary cancer cells transforming into stem cell-like cancer cells. Some chemotherapy for cancer can cause damage to DNA. Researchers need to re-evaluate their long-term effects particularly they have to be cautious with the use of some DNA-damaging agents
The studies by Professor Zhen Yixin are a major development in the cancer stem cell theory. From the current data, there is no effective chemotherapy or radiotherapy drug which can kill cancer stem cells. After chemotherapy, a tumor can shrink or disappear altogether, which, in determining the treatment response, are rated as partial response (PR) or complete response (CR). But it does not mean that everything is fine. This is because the seed cells that is cancer stem cells have not been eliminated; recurrence can happen at any time. Professor Zeng’s studies further found that not only the pre-existing cancer stem cells are not eliminated by chemotherapy drugs, in terms of physics (Professor Zeng used ultraviolet light in the research) and chemistry (Professor Zeng used mitomycin C in the research), ordinary cancer cells will become even hardier and transform into cancer stem cells that is the so called stem-like cancer cells. The studies by Professor Zeng confirms what Professor Tang Zhaoyou has said “…more likely to stimulate cancer metastasis” as correct.