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What harm does pancreatic cancer have to the body?
Like many cancers, early diagnosis and cure of pancreatic cancer are very difficult, so many people who pay attention to their health will pay special attention to pancreatic cancer, but many people still know little about pancreatic cancer. So what harm does pancreatic cancer do to the body? How to find pancreatic cancer early? How to prevent pancreatic cancer?

1, the harm of pancreatic cancer

1. Definition of early pancreatic cancer

Early pancreatic cancer usually refers to pancreatic cancer with a mass diameter of ≤2.0cm, no lymph node metastasis, no pancreatic capsule and peripancreatic infiltration, and no invasion of blood vessels and adjacent organs. The stage belongs to T 1aN0M0. Some authors believe that most pancreatic cancers with tumor diameter 1.0~2.0cm have already had lymph node metastasis, and advocate that tumor diameter ≤ 1.0cm is the standard for early pancreatic cancer. Unless the lesion happens to be located in the duodenal papilla, there are few clinical symptoms except early biliary and pancreatic duct obstruction. Another scholar suggested that the definition of early pancreatic cancer is different from that of small pancreatic cancer. The latter mainly means that the maximum diameter of the tumor is ≤2.0cm, regardless of lymph node metastasis. Therefore, the diagnosis of early pancreatic cancer should focus on screening high-risk groups, molecular biological diagnosis and exploring new imaging methods.

2. High risk factors of pancreatic cancer

The cause of pancreatic cancer is not very clear, and it is mostly related to carcinogens, chronic pancreatitis and gallstones in the environment. In addition, the incidence of depression and alcohol and tobacco addiction is high. Diabetes is closely related to pancreatic cancer, especially new-onset diabetes is a high risk factor for pancreatic cancer. Screening asymptomatic population has no practical value for early diagnosis of pancreatic cancer, but screening clinical high-risk population is expected to improve the early diagnosis rate of pancreatic cancer. Pancreatic Surgery Group of Surgery Branch of Chinese Medical Association put forward the concept of high-risk group of pancreatic cancer in Guidelines for Diagnosis and Treatment of Pancreatic Cancer, including: ① patients over 40 years old with nonspecific symptoms of upper abdomen; ② Patients with family history of pancreatic cancer; ③ Sudden diabetic patients; ④ Patients with chronic pancreatitis, especially chronic familial pancreatitis and chronic calcifying pancreatitis; ⑤ Intraductal papillary myxoma; ⑥ Familial adenomatous polyposis patients; ⑦ Patients with benign lesions undergoing distal subtotal gastrectomy, especially those who have been operated for more than 20 years; Smoking, drinking, and long-term exposure to harmful chemicals.

3. Laboratory diagnosis of early pancreatic cancer

3. 1 serum tumor markers

At present, there is no ideal tumor marker as an early diagnosis and detection method of pancreatic cancer. CA 19-9 is the most widely used glycoprotein antigen at present. The median sensitivity and specificity in the diagnosis of pancreatic cancer were 79%(70%~90%) and 82%(68%~9 1%), respectively. Other markers include CEA, CA50, CA242, CA 125, CA724, MMP-7, TIMP- 1, VEGF, etc. Some of them have been used in clinic. It is now clear that the combined detection of tumor markers is an effective means to improve the early detection rate of pancreatic cancer. In the absence of serum tumor markers with good sensitivity and specificity, protein omics will provide an effective means for screening tumor markers of early pancreatic cancer.

3.2 Genetic testing

Pancreatic cancer is the human malignant tumor with the highest mutation rate of K-ras gene. It is reported that the detection rate of K-ras mutation in malignant tumors is pancreatic cancer (82%), colon cancer (43%), lung cancer (30%) and thyroid cancer (29%) in turn. Almost all K-ras mutations in pancreatic cancer are K-ras 12 codons, which can appear in the early stage of pancreatic cancer carcinogenesis. Some scholars have confirmed that the mutation rate of K-ras gene is gradually increasing in normal tissue of pancreatic cancer margin, pericancerous ductal hyperplasia, pericancerous atypical hyperplasia and pancreatic cancer tissue. At present, PCR-RELP analysis is commonly used to detect the point mutation of K-ras 12 codon, and the samples are biopsy tissues of duodenal juice, pancreatic juice, feces or pancreatic masses. Since more than 90% of pancreatic cancer originated from ductal epithelium, the detection of K-ras gene mutation in pancreatic juice samples has high specificity (88.5%), and pancreatic juice can be collected by endoscopic retrograde cholangiopancreatography (ERCP) to detect related oncogenes. Fine needle aspiration (FNA) combined with cytology and K-ras gene detection can improve the detection rate of pancreatic cancer.

3.3 Telomerase detection

Telomeres are special structures at the ends of chromosomes. In the process of gene mutation and tumor formation, telomeres may be deleted, fused and shortened, resulting in unstable genetic material, infinite cell proliferation and tumor occurrence. Telomerase activity can prevent telomere shortening of somatic cells, so that they can avoid death and have unlimited proliferation ability. In normal human tissues, only hematopoietic stem cells, activated T and B lymphocytes and germ cells have a small amount of telomerase activity, while more than 90% of malignant tumor cells, including 95% of pancreatic cancer, are positive for telomerase. Studies have confirmed that telomerase activity in pancreatic juice has high sensitivity and specificity for pancreatic cancer; There is also a significant difference in the positive rate of telomerase activity between pancreatic cancer tissue and normal pancreatic tissue adjacent to cancer, indicating that telomerase activity is closely related to the differentiation, metastasis and tumor stage of pancreatic cancer tissue. The occurrence, development and malignant transformation of pancreatic cancer require high telomerase level to maintain telomere length more effectively, and often require telomerase reactivation. Telomerase was inhibited in normal and benign pancreatic diseases, but reactivated in pancreatic cancer, indicating that telomerase activation plays an important role in pancreatic cancer. Telomerase activity in pancreatic juice and pancreatic cancer tissue is considered to be an important sign of early diagnosis of pancreatic cancer. It is easy to obtain pancreatic juice by ERCP, and tissue samples obtained by surgery or fine needle aspiration can also be used selectively.

3.4 MicroRNA

MicroRNA regulates a large number of transcription substances at the post-transcriptional level, and plays an important role in the occurrence, development, apoptosis and tumor angiogenesis. It was found that the abnormal expression of microRNA occurred in the early stage of pancreatic cancer, and the abnormal expression in patients with pancreatic cancer had individual heterogeneity, and the sensitivity and specificity of diagnosing pancreatic cancer reached 89% and 93% respectively. The differential expression of microRNA is also specific to cancer tissues. Therefore, microRNA can be used for differential diagnosis of pancreatic cancer and malignant tumors of other organs and tissues. The diagnostic value of microRNA in early pancreatic cancer deserves further study.

3.5 Other molecular biological detection

At present, in the molecular pathological diagnosis of pancreatic cancer, there are at least dozens of oncogenes, tumor suppressor genes and their expressed proteins, growth factors, adhesion molecules and apoptosis-regulating genes, such as P 16, P53, MUC- 1 and MUC-4mRNA. These markers are related to the occurrence and development of pancreatic cancer. Combined detection of these tumor markers is helpful for early diagnosis of pancreatic cancer, but most of them are still in the experimental research stage.

4 image diagnosis

4. 1 Abdominal ultrasound

The detection rate of pancreatic cancer with a mass diameter less than ≤2.0cm by transabdominal ultrasound is less than 30%, but it is still a routine screening method. Ultrasound-guided fine needle aspiration (FNA) is of great significance in differentiating benign from malignant pancreatic tumors.

4.2CT and PET-CT

Thin-slice spiral CT has high spatial resolution and can be used for three-dimensional reconstruction of tumors. The diagnostic sensitivity and specificity of pancreatic cancer with a mass diameter less than ≤2.0cm were 77% and 100%, respectively. Dual-phase contrast-enhanced scanning can not only determine the tumor itself, but also determine whether the peripancreatic artery and vein are invaded and whether there is lymph node metastasis, which can provide accurate preoperative evaluation for clinical treatment and improve the success rate of surgical treatment. Therefore, thin-slice spiral CT dual-phase or three-phase enhanced scanning (arterial phase, pancreatic phase and liver phase) is the most ideal noninvasive imaging method for the diagnosis of early pancreatic cancer. PET-CT is fluorescent deoxyglucose (18F-FDG) labeled with18f, which is injected into cells to participate in glucose metabolism. During the growth of malignant tumor cells, glucose consumption is greater than that of normal tissues, and a large amount of 18F-FDG is ingested. PET-CT imaging shows abnormal radioactive concentration in malignant tumor, that is, hypermetabolic disease. This method is mainly used to find small lesions and distant metastasis. Ye Hui et al. thought that 18F-FDGPET/CT was positive in 37 cases, with sensitivity of 92.5%, specificity of 83.3% and accuracy of 9 1.3%. The sensitivity, specificity and accuracy of plain CT scan and enhanced CT scan were 75.0%, 66.7% and 73.9% respectively. The sensitivity, specificity and accuracy of PET/CT in diagnosing pancreatic cancer are obviously higher than that of CT. However, PET-CT will produce some false positive results in active chronic pancreatitis, serous cystadenoma, retroperitoneal fibrosis and a large number of lymphocytes in pancreatic head masses. In addition, it can not provide accurate anatomical location and is expensive, which limits its routine clinical application.

4.3 Magnetic Resonance Imaging

MRI is a noninvasive, safe and contrast-free diagnostic method, and its diagnostic accuracy is 75%~95%. It can clearly show the relationship between tumor and blood vessels, which plays an important role in judging the resectability of pancreatic cancer surgery. However, the spatial resolution of MRI is poor, and the diagnostic effect of early pancreatic cancer is limited. With the research and application of magnetic resonance spectroscopy (MRS), it provides a more objective qualitative analysis method for the early diagnosis and differential diagnosis of pancreatic cancer. Molecular-based magnetic resonance imaging, fluorescence imaging and preparation of magnetic nanoparticles are still in the research stage.

5 Endoscopic examination and endoscopic ultrasound examination

5. 1 ERCP can display pancreatic duct, bile duct and ampulla at the same time, which is very valuable for differential diagnosis of unexplained obstructive jaundice. Irregular stenosis of the main pancreatic duct, rat tail sign at the end, destruction of the side branches of the main pancreatic duct, contrast agent overflowing into the tumor area and "double tube sign" can be found, but the detection rate of early lesions without dilatation of the main pancreatic duct is low [20].

5.2 Endoscopic ultrasound

Endoscopic ultrasound combined with fine needle aspiration cytology can improve the detection rate of pancreatic cancer to 85%~90%. Because intracavitary ultrasound can avoid the influence of intestinal gas, we can get high-resolution images of the pancreas by examining the stomach and duodenum near the pancreas, and find lesions with a size of 2.0~3.0mm, which is more effective than transabdominal ultrasound and CT. At present, from the morphological point of view, EUS is one of the best methods to obtain local images.

5.3 Intrapancreatic ultrasound (PIDUS)

PIDUS technology is a new endoscope-assisted method, which obtains high-resolution images by using a small intracavity high-frequency ultrasonic probe.

PIDUS is to introduce an ultrasonic probe with a guide wire into the pancreatic duct for examination during ERCP, which can find carcinoma in situ and small pancreatic cancer at an early stage. PIDUS can clearly show tumor invading blood vessels and pancreatic duct, which is of great significance for differential diagnosis of pancreatic lesions. The sensitivity and specificity of diagnosing pancreatic cancer were 100% and 92% respectively. Its disadvantage is that it is difficult to operate. Once the tumor causes pancreatic duct stenosis, the ultrasonic probe is not easy to pass.

5.4 Contrast-enhanced ultrasound and ultrasonic elastography technology

The principle of contrast-enhanced ultrasound is to enhance the contrast of blood vessels after the contrast agent enters the tumor blood vessels, so as to clearly display the blood vessel distribution and blood flow, and can display the pancreatic and tumor microvessels. Malignant lesions showed uneven enhancement or localized clustering, while benign lesions showed punctate, linear and annular enhancement. Elastic imaging technology is based on the difference of hardness of different tissues, and the echo signal is moved by external force, which is quantized into real-time color image and elastic coefficient. Endoscopic ultrasonic elastography, as a new method of simulated biopsy, has high accuracy in differential diagnosis of solid pancreatic lesions. Combined with contrast-enhanced ultrasound and endoscopic ultrasound elastography, the accuracy of early pancreatic cancer diagnosis can be improved to about 90%.

summary

Endoscopic ultrasound and intra-pancreatic ultrasound are the perfect combination of imaging and endoscopic techniques, which play an important role in the diagnosis of early pancreatic cancer. With the development and application of new contrast agents, the ability of CT and MRI enhanced scanning to detect and characterize tumors has been continuously improved. Gene chip technology can carry out multi-gene joint detection, which provides a direction for gene diagnosis of tumors. If tumor markers with high sensitivity and specificity for pancreatic cancer can be found by protein omics, combined with endoscopic ultrasound and other means, the early diagnosis of pancreatic cancer will usher in a brand-new situation.

2. How to prevent pancreatic cancer

Measure 1: Good living habits

Good living habits are the best measures to prevent pancreatic cancer. According to medical investigation and statistics, if people stop smoking, the number of cancers in the world will be reduced by one third in five years. Second, don't drink. Alcohol and tobacco are extremely acidic substances, and people who smoke and drink for a long time are prone to acidic constitution.

Measure 2: Eat reasonably.

According to many years of clinical observation, it is found that eating too much salty and spicy food, or overheating, supercooling, expired and deteriorated food is easy to induce the disease; Therefore, for people who are old and weak or suffer from certain genetic diseases, they can eat some anti-cancer foods and alkaline foods with high alkali content as appropriate to maintain a good mental state.

Measure 3: Strengthen exercise.

In daily life, we should also pay attention to strengthening physical exercise, strengthening physical fitness, and exercising more in the sun. Hyperhidrosis can excrete acidic substances in the body with sweat to avoid forming acidic physique.

Measure 4: Have a good attitude.

Experts point out that stress is an important cause of cancer. Traditional Chinese medicine believes that stress leads to fatigue and physical weakness, which leads to the decline of immune function, endocrine disorder and metabolic disorder, leading to the deposition of acidic substances in the body; Stress can also lead to mental stress, causing qi stagnation and blood stasis, toxic fire invagination and so on.

Good living habits are the best measures to prevent pancreatic cancer. Reasonable diet, reasonable work and rest, strengthening exercise and maintaining a good attitude will make it difficult to find you in any disease.