According to the 2020 Annual Work Report of the National Cancer Center, my country's overall 5-year cancer survival rate is 40.5%. That is to say, nearly 60% of cancer patients cannot achieve clinical cure. Recurrence and metastasis are important reasons why cancer patients cannot be cured.
Fans who love to watch Hong Kong comedy are familiar with the name " Ng Man-tat ". He is one of the few gold medal supporting roles in Hong Kong, especially the comedy movies that collaborate with Stephen Chow , which makes people laugh.
However, on February 22, the news that "Ng Man-tat suffered from liver cancer" on Weibo was not laughing. According to Wu Mengda’s friends, Wu Mengda suffered from liver cancer and has now undergone surgery and entered the chemotherapy stage.
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So, does Uncle Da have removed the tumor mean that movie fans can breathe a sigh of relief? In fact, in the long journey of anti-cancer, surgical removal of tumors may be just the first step in the "Long March". Because the tumor has been waiting for an opportunity to make a comeback at any time - relapse, or go to other places to make trouble - metastasis. Therefore, fighting a protracted battle with tumors is the key to winning the fight against cancer.
Clinical cure is not as simple as removing a tumor
Many people believe that everything will be fine if the tumor is removed through surgical surgery. Is surgery really equivalent to clinical cure?
"For cancers of different types and stages, the answers are obviously different, and they cannot be generalized." Professor Ba Yi, chairman of the Tumor Support and Treatment Professional Committee of the Chinese Anti-Cancer Association and vice president of the Cancer Hospital of Tianjin Medical University, gave an example, saying that most patients with thyroid cancer and stage I gastric cancer have the opportunity to be cured if they only undergo radical surgery, but for most malignant tumors, clinical cure cannot be achieved through surgical procedures.
currently recommends a multidisciplinary cooperation mechanism in clinical practice, and selects individualized comprehensive treatment plans such as surgery, radiotherapy, chemotherapy, targeted therapy, etc. based on the patient's initial diagnosis of tumor stage and patient's physical condition. After standardized treatment, after 5 years of follow-up, there are still no abnormal symptoms (such as local bleeding, pain) or signs (such as abnormal lymph node enlargement). No clear metastatic lesions were found by imaging examinations such as ultrasound and CT. It can be considered that "clinical cure" is achieved, which is what doctors usually call "5-year survival rate".
Why do cancer cells look like "Xiaoqiang" that cannot be killed
According to the 2020 Annual Work Report of the National Cancer Center, the overall 5-year survival rate of cancer in my country is 40.5%. That is to say, nearly 60% of cancer patients cannot achieve clinical cure.
"Recurrence and metastasis are important reasons why cancer patients cannot be cured." Professor Ba Yi said that there is no conclusion on the mechanism of cancer recurrence and metastasis, and it is still a hot topic of scientific research.
is the stem cell hypothesis. After various treatments, most of the cancer cells died, but a small number of cells survived. What survives are cancer stem cells, like the roots of a big tree, with the potential for self-renewal and infinite proliferation, are resistant to a variety of therapeutic drugs, and their mobility and migration abilities increase the risk of cancer metastasis.
In addition to the stem cell hypothesis, scientists also found that cancer cells also have the ability to "dormant" in order to survive. The tumor dormant hypothesis is also one of the recognized mechanisms for cancer recurrence. The top journal Nature Reviews once summarized the life cycle of dormant cancer cells: diffuse cancer cells will first choose the appropriate ecological niche, but the characteristics of microenvironment such as hypoxia will inhibit cell proliferation and cause cell cycle arrest. At this time, cancer cells will be reprogrammed and gradually adapt to the surrounding environment, and start to hibernate for a long time after having the ability to escape immune surveillance. When cancer cells slowly accumulate enough energy in a barren environment, they will be activated, or activated due to microenvironmental factors.
"Cancer metastasis includes multiple steps such as cancer cell infiltration and angiogenesis. In addition to these two hypotheses related to metastasis, there are also epithelial-interstitial transformation hypothesis, seed-soil hypothesis, etc.." Professor Ba Yi said that there is a very complex biological mechanism behind each hypothesis, but there is no clear statement on which is the real cause of metastasis recurrence.
Image source: Visual China
Both body and mind must be "hard" to have hope of "winning the battle"
Data from the National Cancer Center shows that from 2012 to 2015, the 5-year survival rate of pancreatic cancer, known as the "king of cancer", was only 7.2%, while thyroid cancer was as high as 84.3%.
Why is the same malignant tumor but the ability to recurrence and metastasis is very different?
"Due to the heterogeneity of tumors, different types and different degrees of differentiation, the invasion, metastasis, recurrence abilities and sensitivity to treatment are also very different." Professor Ba Yi explained that the fundamental reason is the difference in the inherent gene regulation level of tumor cells. After using CRISPR technology to give each cancer cell a unique "tag" and track the evolution and metastasis of them and their offspring, scientists discovered the "hot spot" genes that cause metastasis (genes such as IF127 and REG4 are related to high metastasis potential).
In addition to the tumor itself, the host factors also have a great impact. For example, for the same tumor type, the later the staging, the heavier the tumor burden and the worse the prognosis; patients who receive standardized treatment as planned have better prognosis than patients with poor compliance; patients' physical and mental factors, economic factors, family and social factors will also affect the prognosis.
"It is not difficult to find clinically that patients with good physical fitness, patients with positive attitudes in life, and patients with more support from relatives and friends can better tolerate treatment and have a better chance of benefiting from treatment." Professor Ba Yi said.
"Weapon" upgrade is expected to improve the survival rate of patients
"How to improve the survival rate of cancer patients is a concern for every clinician." Professor Ba Yi introduced that there are countless new progress and new achievements in medical research, but there may be a long way to go to improve the survival of patients.
First of all, exploring clinical research on new drugs and new treatment models is the most direct way to improve the survival rate of cancer patients. The most popular cancer treatment drug today is the immune checkpoint inhibitor . Malignant tumors can escape attacks from the immune system, and immune checkpoint inhibitors can make the immune system rise again to attack tumor cells. Professor Baryi introduced that the use of immune checkpoint inhibitors has been successful in the treatment of various solid tumors.
"The new treatment model is mainly multidisciplinary discussion. Compared with the previous single-discipline fighting alone, the current multidisciplinary discussion collaboration model of oncology can also improve the survival rate of patients." Professor Ba Yi gave an example. For advanced patients such as liver metastasis in bowel cancer, there is still a chance of cure based on the cooperation between internal medicine, surgery, interventional, radiotherapy and other parties.
Secondly, translational studies are also accumulating energy to improve the survival rate of patients. For example, many translational studies have begun to look for molecular markers for predicting efficacy, and the discovery of these markers will help doctors screen treatment options for different patients. For example, related studies have found that JAK1/2 mutations, PTEN gene mutations, etc. are negatively correlated with the efficacy of in immunotherapy; POLD1/POLE gene mutations, etc. are positively correlated with the efficacy of immunotherapy. When doctors see patients carrying these gene mutations, they will naturally make judgments on the choices of immunotherapy.
Finally, the development of basic research has always been the backing of clinical progress. New therapeutic targets and new therapeutic drugs all rely on the support of basic research. Professor Ba Yi gave an example saying that obesity has been shown to be related to the occurrence of cancer and the worse prognosis of patients. A study published in the journal Cell in December 2020 showed that obesity can make cancer cells win in the competition with immune cells (CD8+ T cells) for fuel. On a high-fat diet, cancer cells can be metabolically reprogrammed to increase fat uptake and utilization, while CD8+ T cells cannot. This study lets us know that the tug-of-war between T cells and tumor cells will change due to obesity. Although it is not yet possible to identify clear therapeutic targets, this discovery opens the door to new strategies to combat cancer through metabolic weaknesses.
"Under the current circumstances, receiving standardized and reasonable anti-tumor treatment is the most effective way to reduce recurrence and metastasis and prolong survival. Regular review and follow-up are the most effective way to detect recurrence and metastasis in the early stage." Professor Ba Yi emphasized.
Source: Science and Technology Daily
