Cancer screening is for healthy people who have not yet developed abnormal symptoms, and if any abnormalities have appeared, they need to seek medical attention as soon as possible. So what exactly do you need to check for and how should you perform screening to detect cancer through early screening? Screening for the general population For the general population, the three most mature and well-documented cancer screenings are breast cancer, cervical cancer and colorectal cancer. Among women, breast cancer is the most common malignancy. The prognosis of breast cancer depends on the stage of the disease. The cure rate of ductal carcinoma in situ in early stage breast cancer can reach over 95%, and more chances of breast preservation can be obtained. Therefore, early detection and treatment are very important. There are two main means of breast cancer screening: one is physical examination, in which the doctor palpates the examined person’s breast and axillary lymph nodes, and the other is mammography (mammogram). In addition, ultrasound and other methods can be used as an adjunct. Among them, mammography is the most classic and well-documented screening method, but this screening method is mainly suitable for women over 40 years old, and young women without high-risk factors do not need to undergo it routinely. The National Comprehensive Cancer Network (NCCN) published clinical guidelines for breast cancer and the Chinese Anti-Cancer Society Guidelines and Specifications for Breast Cancer Diagnosis and Treatment (2013 Edition) both agree that non-high-risk women between the ages of 20 and 39 do not need to undergo routine mammograms, as long as they undergo regular physical examinations, while it is recommended that women over the age of 40 undergo mammograms once a year. In China, it is recommended that the frequency of screening be reduced appropriately for older women, while women with a family history and other risk factors also need to be monitored more closely. As for self-examination of the breast, its effectiveness is not currently supported by sufficient evidence. However, close monitoring of changes in one’s health and physical condition is still worth advocating. Cervical cancer Cervical cancer is also a common malignancy that threatens women’s health. There are no obvious signs and symptoms in the early stages of cervical cancer, but lesions can be effectively detected through screening. There is now ample evidence that cervical cancer screening can help in early diagnosis and reduce mortality. There are two main tests that are used in cervical cancer screening. One is cervical cytology, in which cervical cells are collected and observed through a microscope for normal cell morphology. This test is minimally risky and invasive and can be effective in reducing cervical cancer mortality rates. Another test is the HPV (human papillomavirus) test. Some subtypes of HPV infection are important risk factors for cervical cancer, so testing for HPV can also help doctors identify high-risk individuals of concern. However, it should be noted that a positive HPV test does not indicate the presence of cervical cancer, and a significant proportion of women with HPV infection do not develop cervical cancer, so there is no need to be overly concerned about the test results. In May 2012, the National Comprehensive Cancer Network (NCCN) updated its guidelines for cervical cancer screening, giving the following recommendations: Cervical smear screening is recommended for women aged 21 to 29 years alone, once every 3 years. In principle, screening is required only after the initiation of sexual intercourse, and women under 21 years of age do not need to be screened. Women between 30 and 65 years of age can be screened with combined HPV and Pap smear once every 5 years, or with Pap smear alone once every 3 years. Screening can be discontinued for women over 65 years of age who have had consecutive negative results from previous screenings. There is some variation in the recommendations for cervical cancer screening among institutions, for example, Hong Kong recommends annual screening for the first two years and then every three years thereafter if the results are negative, depending on the professional doctor consulted. Colorectal Cancer According to 2012 data, colorectal cancer is the third most prevalent malignancy in the world. Colorectal cancer also has no obvious symptoms in the early stage, sometimes only positive fecal occult blood. The prognosis of colorectal cancer depends on early diagnosis and surgical cure. Screening for colorectal cancer is mainly performed in people aged 40 to 50 years or older, and the main detection methods are fecal occult blood and colonoscopy. In the colorectal cancer screening guidelines issued by the American College of Physicians (ACP) in 2012, the general population is recommended to start screening at age 50 with one fecal occult blood test per year and one colonoscopy every 10 years. The American Cancer Society (ACS) considers sigmoidoscopy, double-contrast barium enema or CT colonography as optional screening tools in addition to colonoscopy. If risk factors such as family history exist, screening should be started earlier and more frequently as appropriate. Specific protocols will also depend on individual circumstances and follow the advice of the physician. For elderly people over 75 years of age or adults with an expected survival of less than 10 years, the benefits of screening may not outweigh the risks and colorectal cancer screening should be discontinued at this time. Screening for high-risk groups In addition, there are some cancers that are targeted mainly in high-incidence areas and high-risk groups, including lung cancer, stomach cancer, liver cancer, etc. Lung Cancer Lung cancer is an important disease that endangers human health, and it ranks first among all malignant tumors in terms of incidence and mortality. For lung cancer, early detection, early diagnosis and early treatment are also of great significance. However, current research data do not support widespread lung cancer screening in the overall population, so relevant organizations generally recommend regular screening only for specific high-risk groups. The most reliable method to screen for lung cancer is low-dose spiral CT (LDCT), which is more sensitive in detecting suspicious lesions, has stronger evidence of reducing lung cancer mortality, and is within acceptable risk limits compared to radiographs. The American Cancer Society (ACS) recommends regular annual low-dose CT screening for high-risk individuals aged 55 to 74 years, where high-risk groups include those with a history of smoking (at least 30 pack-years; pack-years = number of packs smoked per day x number of years of continuous smoking), current smokers, and those who have not quit smoking for more than 15 years. The definition of high-risk groups varies slightly in the Chinese screening protocol, so please consult your doctor for details. Liver cancer Primary liver cancer is the third most common malignancy in China and has the second highest mortality rate of all malignancies. Liver cancer is insidious in its onset, so screening for high-risk groups is also very important. Currently, there are international guidelines for liver cancer treatment, including the National Comprehensive Cancer Network (NCCN) clinical practice guidelines for liver cancer, the American Association for the Study of Liver Diseases (AASLD) clinical treatment guidelines for liver cancer, the British Society of Gastroenterology (BSG) treatment guidelines, and the consensus developed by the American College of Surgeons (ACS), and Chinese experts have also developed the “Expert Consensus on Standardized Diagnosis and Treatment of Primary Liver Cancer” based on national conditions. Chinese experts have also formulated the Expert Consensus on the Standardized Diagnosis and Treatment of Primary Liver Cancer according to national conditions. All of these guidelines place great emphasis on early screening and surveillance of liver cancer. These guidelines recommend that all people at high risk for liver cancer should be screened. People at high risk for liver cancer include those infected with hepatitis B and C viruses, alcoholics, and others. Since tumor volume doubles every 6 months on average, screening is generally performed every 6 months for those at risk. Because of the relatively late onset of cancer in women, Chinese guidelines for cancer screening and early diagnosis and treatment suggest that screening for high-risk groups can be started at age 35 for men and 45 for women. The ideal screening protocol is the combined application of alpha-fetoprotein (AFP) and abdominal ultrasound (US), which can greatly reduce the rate of missed diagnoses. However, if economic conditions do not allow, screening with abdominal ultrasound alone is possible. If a qualified ultrasonographer is not available, you can also check the blood for AFP alone. Of course, there are some methods with greater resolution and power besides ultrasound, such as CT, magnetic resonance imaging (MRI), and PET-CT, but considering the economic cost and medical conditions, these are not recommended as routine tests for liver cancer screening. Gastric Cancer Gastric cancer is one of the most common malignancies in China, so the issue of screening for gastric cancer deserves attention. The primary method for screening gastric cancer is gastroscopy, and other methods include H. pylori test, tumor marker test, etc. These methods are not highly specific and sensitive, so they are generally not recommended; while serum plasminogen test is still in the clinical trial stage in China, which is inconclusive. Japan, which has the highest incidence of gastric cancer, advocates annual gastroscopy for people over forty years old and has been implementing it for many years, which is one of the reasons why the 5-year survival rate of gastric cancer patients in Japan has been the highest in the world. At present, gastric cancer screening in China is mainly conducted in high-risk groups, which include men and women over the age of 40 who live in areas with a high incidence of gastric cancer or have high-risk factors such as H. pylori infection, gastric ulcer, and family history. Depending on the risk classification, high-risk groups may undergo direct gastroscopy or other non-invasive primary screening tests first. Others In China, screening for esophageal and nasopharyngeal cancers is also being conducted in specific high-incidence regions and among high-risk groups. Two other cancers, prostate cancer and endometrial cancer, are mentioned in the American Cancer Society (ACS) guidelines. Screening for these two cancers is not currently recommended for the general population on a routine basis, although the ACS recommends that men over the age of 50 consult with their physician about prostate screening and that women pay close attention to any abnormal uterine bleeding and seek prompt medical attention.