A-Hsiang, whose age is now in 80s, diagnosed with colorectal cancer around 20 years ago. The cancer recurred five years after the treatment. Following first recurrence, the cancer reappeared every two to three years; as result A-Hsiang went through four liver metastases, fortunately for him, A-Hsiang was able to stay on top of the disease by having regular follow-up care. Through regular cancer screening by using liquid biopsy, early signs of recurrent cancer were promptly detected and tumors removed. Dr. Hwei-Ming Wang(王輝明), Deputy Director of the Department of Surgery at China Medical University Hospital, pointed out that the non-invasive cancer screening is very precise and can help doctors detect any signs of cancer recurrence at an early stage. In addition, pharmacogenetic testing also gives patients the opportunity to choose the targeted therapy drug that is most suitable, reducing the agony of having repeated chemotherapy, tackling the root cause and regularly having follow-up care to significantly improve the survival rate of colorectal cancer patients.
Regular follow-up care to prevent recurrence and metastasis
Dr. Wang said that a colorectal cancer recurrence can be categorized as low risk, moderate risk and high risk. Clinical analysis shows that about 20 percent of patients belong to the high-risk recurrence category and Dr. Wang urged patients to have regular follow-up check to prevent cancer from recurring. He stressed that just by having the surgery, chemotherapy or the targeted therapy does not mean the patient is fully recovered. Research showed that the overall recurrence rate within two years following colorectal cancer treatment is as high as 40 percent. Recurrence rate stands at 5 percent in the fifth year after the treatment. Therefore, patients at high risk of recurrence are suggested to have regular follow-up care through non-invasive genetic testing for cancer risk. A pre-emptive strategy should be applied once the test result is positive. These patients are also advised to have follow-up care every three months in the first two years following the treatment, and every six months in the third year. Non-invasive genetic testing for cancer risk is precise, rapid and with no recovery time required, which helps doctors to stay updated with data.
There is a number of ways to monitor cancer cells. Dr. Wang said, in the past, colonoscopy is used to detect cancer cells. However, due to the limitation of image resolution, it is difficult to detect tumors smaller than 0.5 cm, and patients might miss the best opportunity of treatment. Tissue biopsy is an invasive surgical biopsy that takes a sample of tissue from the lump to conduct genetic analysis. Since only a part of the tissue is taken, it is hard to have a more comprehensive view of the changes of cancer cells. Moreover, with the limited size of the lump, it can be challenging to take samples for several times. Therefore, these methods have been proven hard to follow-up on patients at high risk. Now, with the advancement of medical technology, it is possible to do liquid biopsy on a sample of blood and test circulating tumor DNA (ctDNA), with the accuracy rate standing at as high as 98 percent. Once abnormalities are found in the patient’s blood, further tests can be arranged for early treatment to minimize the impact of cancer cells.
Ph.D. Chia-Cheng Hung (洪加政), doctor of Graduate Institute of Medical Genomics and Proteomics at National Taiwan University, pointed out that when dead cancer cells get broken down, their contents, including ctDNA, are released into the bloodstream. ctDNA can reflect the genetic changes of patient’s tumor real-time. Research also shows that liquid biopsy through blood testing of ctDNA can detect colorectal cancer earlier than colonoscopy by 188 days. Currently, Taiwan has genetic testing companies that do tests and provide test results in ten working days, helping physicians to promptly conduct analysis and arrange for treatment.
Colorectal cancer still upheld its standing as the most common cancer in Taiwan.
Genetic testing enables early detection and treatment for those at high risk.
The cancer report conducted by the Ministry of Health and Welfare of Health Promotion Administration shows that from 2006, colorectal cancer has remained as the most common cancer for 11 years. On average, about 41 people are diagnosed with the disease every day. Dr. Wang said that a large amount of environmental carcinogens such as pesticide, heavy metal, dioxin, aflatoxin may enter human food chain through animal-based diet. Moreover, animal-based foods, once cooked over high heat, will release carcinogens such as polycyclic aromatic hydrocarbons and heterocyclic amines. Having too much animal-based foods is a reason why colorectal cancer has remained a common cancer for Taiwanese people.
During the early stage of colorectal cancer, there may be no symptoms at all. When symptoms such as bleeding from the bowel or a change in bowel habit appears, patients often mistake the symptoms as hemorrhoids or constipation, and would not go for treatment. The five-year survival rate at early stage of colorectal cancer is nearly 90 percent, while the survival rate for Stage IV colorectal cancer drops significantly to less than 20 percent. Therefore, Dr. Wang advised the public to have regular check-up. Currently, the government offers people aged between 50 to 74 a free colorectal cancer screening every two years (immunochemical fecal occult blood test, iFOBT), a test that checks for occult blood in the stool. For those with a family history of colorectal cancer or those who often have deep-fried or grilled foods, both belong to high-risk group, they are advised to do non-invasive genetic testing as early as possible. ctDNA can easily be tested with a sample of blood. Detecting cancer cell at stage 0 cancer is truly the proactive approach of preventive care.