What harm does pancreatic cancer have to the body?

Pancreatic cancer, like many cancers, is very difficult to diagnose and cure early, so many people who care about 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 lymph node metastasis has occurred in most pancreatic cancers with a mass diameter of 1.0~2.0cm, and advocate that the tumor diameter ≤ 1.0cm is the standard for early pancreatic cancer. Unless the lesion happens to be located in the duodenal papilla, there are almost no 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 refers to the maximum diameter of tumor ≤2.0cm, which has nothing to do with 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 cholelithiasis in the environment. In addition, the incidence of depression and alcohol and tobacco addiction is also 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 those with 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; 8. 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 for 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. At present, it is 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 rates of K-ras mutation in malignant tumors are 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 the commonly used method to detect K-ras 12 codon point mutation, 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, it is highly specific (88.5%) to detect K-ras gene mutation in pancreatic juice samples, 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

Telomere is a special structure at the end of chromosome. In the process of gene mutation and tumor formation, telomeres may show deletion, fusion and sequence shortening, leading to 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 a small amount of telomerase activity exists in hematopoietic stem cells, activated T and B lymphocytes and germ cells, while more than 90% of malignant tumor cells (including 95% of pancreatic cancer) are telomerase positive. 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 need higher telomerase level to maintain telomere length more effectively, and often need 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. Obtaining pancreatic juice by ERCP is simple and easy, and tissue samples obtained by surgery or fine needle aspiration can also be selectively used.

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 to differentiate pancreatic cancer and malignant tumor from 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, 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 are involved. These markers are related to the occurrence and development of pancreatic cancer. The combined detection of these tumor markers is helpful for the 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 or equal to ≤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 of pancreatic cancer with a mass diameter less than ≤2.0cm was 77%, and the specificity was 100%. Dual-phase contrast-enhanced scanning can not only determine the pancreatic cancer mass itself, but also determine whether the peripancreatic artery and vein are invaded and whether there is lymph node metastasis, which provides accurate preoperative evaluation for clinical treatment and improves 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 and non-invasive imaging examination 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 higher 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 and others 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, in the active stage of chronic pancreatitis, serous cystadenoma, retroperitoneal fibrosis and a large number of lymphocytes in the pancreatic head mass, PET-CT can produce some false positive results. 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, and 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, 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. It can find the irregular stenosis of the main pancreatic duct, the tail sign at the end, the destruction of the side branches of the main pancreatic duct, the overflow of contrast agent into the tumor area, the "double tube sign" and so on, but the detection rate of the early lesions 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 obtain high-resolution images of the pancreas by examining the stomach and duodenum near the pancreas, and find lesions with a size of 2.0 ~ 3.0 mm, 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 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 tumors 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 pancreas and tumor microvessels. Malignant lesions showed uneven enhancement or localized cluster enhancement, while benign lesions showed punctate, linear and annular enhancement. Elastic imaging technology is based on the hardness difference between different tissues, and the echo signal is moved by external force, which is quantized into real-time color images and elastic coefficients. Endoscopic ultrasonic elastography, as a new method of simulated biopsy, has high accuracy in differential diagnosis of solid pancreatic lesions. Combining contrast-enhanced ultrasound with endoscopic elastography can improve the diagnostic accuracy of early pancreatic cancer 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. Due to 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 we can find tumor markers with high sensitivity and specificity for pancreatic cancer through protein omics combined with endoscopic ultrasound, the early diagnosis of pancreatic cancer will usher in a new situation.

2. How to prevent pancreatic cancer

Measures 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 can easily lead to acidic constitution.

Measure 2: Eat reasonably.

According to many years of clinical observation, eating too much salty and spicy food, or overheating, supercooling, expired and deteriorated food is easy to induce this disease; Therefore, people who are old and weak or have genetic diseases should 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, exercising in the sun more, sweating more can excrete acidic substances in the body with sweat and 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.