|Purpose||detection of cancer prior to onset of symptoms(via several tests/imaging)|
Cancer screening aims to detect cancer before symptoms appear.This may involve blood tests, urine tests, DNA tests other tests, or medical imaging. The benefits of screening in terms of cancer prevention, early detection and subsequent treatment must be weighed against any harms.
Universal screening, also known as mass screening or population screening, involves screening everyone, usually within a specific age group.Selective screening identifies people who are known to be at higher risk of developing cancer, such as people with a family history of cancer.
Screening can lead to false positive results and subsequent invasive procedures.Screening can also lead to false negative results, where an existing cancer is missed. Controversy arises when it is not clear if the benefits of screening outweigh the risks of the screening procedure itself, and any follow-up diagnostic tests and treatments.
Screening tests must be effective, safe, well-tolerated with acceptably low rates of false positive and false negative results. If signs of cancer are detected, more definitive and invasive follow-up tests are performed to reach a diagnosis. Screening for cancer can lead to cancer prevention and earlier diagnosis. Early diagnosis may lead to higher rates of successful treatment and extended life. However, it may also falsely appear to increase the time to death through lead time bias or length time bias.
The goal of cancer screening is to provide useful health information which can guide medical treatment. [ medical citation needed ] A good cancer screening is one which would detect when a person has cancer so that the person could seek treatment to protect their health. Good cancer screening would not be more likely to cause harm than to provide useful information. In general, cancer screening has risks and should not be done except with a medical indication.
Different kinds of cancer screening procedures have different risks, but good tests share some characteristics.If a test detects cancer, then that test result should also lead to options for treatment. Good tests come with a patient explanation of why that person has high enough risk of cancer to justify the test. Part of the testing experience is for the health care provider to explain how common false positive results are so that the patient can understand the context of their results. If multiple tests are available, then any test should be presented along with other options.
Screening for cancer is controversial in cases when it is not yet known if the test actually saves lives.Screening can lead to substantial false positive result and subsequent invasive procedures. The controversy arises when it is not clear if the benefits of screening outweigh the risks of follow-up diagnostic tests and cancer treatments. Cancer screening is not indicated unless life expectancy is greater than five years and the benefit is uncertain over the age of 70.
Several factors are considered to determine whether the benefits of screening outweigh the risks and the costs of screening.These factors include:
Breast cancer screening is the medical screening of asymptomatic, apparently healthy women for breast cancer in an attempt to achieve an earlier diagnosis. The assumption is that early detection will improve outcomes. A number of screening tests have been employed, including clinical and self breast exams, mammography, genetic screening, ultrasound, and magnetic resonance imaging. The use of mammography in universal screening for breast cancer is controversial as it may not reduce all-cause mortality and for causing harms through unnecessary treatments and medical procedures. Many national organizations recommend it for most older women.
Cervical screening by the Pap test or other methods is highly effective at detecting and preventing cervical cancer, although there is a serious risk of overtreatment in young women up to the age of 20 or beyond, who are prone to have many abnormal cells which clear up naturally.There is a considerable range in the recommended age at which to begin screening around the world. According to the 2010 European guidelines for cervical cancer screening, the age at which to commence screening ranges between 20–30 years of age, "but preferentially not before age 25 or 30 years", depending on the burden of the disease in the population and the available resources.
In the United States the rate of cervical cancer is 0.1% among women under 20 years of age, so the American Cancer Society as well as the American College of Obstetricians and Gynecologists strongly recommend that screening begin at age 21, regardless of age at sexual initiation or other risk-related behaviors.For healthy women aged 21–29 who have never had an abnormal Pap smear, cervical cancer screening with cervical cytology (Pap smear) should occur every 3 years, regardless of HPV vaccination status. The preferred screening for women aged 30–65 is "co-testing", which includes a combination of cervical cytology screening and HPV testing, every 5 years. However, it is acceptable to screen this age group with a Pap smear alone every 3 years. In women over the age of 65, screening for cervical cancer may be discontinued in the absence of abnormal screening results within the prior 10 years and no history of CIN 2 or higher.
Screening for colorectal cancer, if done early enough, is preventive because almost allcolorectal cancers originate from benign growths called polyps, which can be located and removed during a colonoscopy (see colonic polypectomy ).
The US Preventive Services Task Force recommends screening for colorectal cancer using fecal occult blood testing, sigmoidoscopy, or colonoscopy, in adults, beginning at age 50 years and continuing until age 75 years. years screening is not recommended. A new enzyme method for colorectal cancer screening is the M2-PK Test, which is able to detect bleeding and non-bleeding colorectal cancers and polyps. In 2008, Kaiser Permanente Colorado implemented a program that used automated calls and sends fecal immunochemical test kits to patients who are overdue for colorectal cancer screenings. The program has increased the proportion of all eligible members screened by 25 percent. DNA testing with Cologuard test has been FDA-approved.For people over 75 or those with a life expectancy of less than 10
In England, adults are screened biennially via faecal occult blood testing between the ages of 60 and 74 years.
When screening for prostate cancer, the PSA test may detect small cancers that would never become life-threatening, but once detected will lead to treatment. This situation, called overdiagnosis, puts men at risk for complications from unnecessary treatment such as surgery or radiation. Follow up procedures used to diagnose prostate cancer (prostate biopsy) may cause side effects, including bleeding and infection. Prostate cancer treatment may cause incontinence (inability to control urine flow) and erectile dysfunction (erections inadequate for intercourse).As a result, in 2012, the U.S. Preventative Services Task Force (USPSTF) recommended against prostate-specific antigen (PSA) based screening for prostate cancer finding, "there is a very small potential benefit and significant potential harms" and concluding, "while everyone wants to help prevent deaths from prostate cancer, current methods of PSA screening and treatment of screen-detected cancer are not the answer."
More recently, Fenton's 2018 review(conducted for the USPSTF) focused on the two highest quality randomized control studies of the costs and benefits of PSA screening, and the findings illustrate the complex issues associated with cancer screening. Fenton reports that the screening of 1,000 men every four years for 13 years reduces mortality from prostate cancer by just one. More specifically, of those 1,000 men: 243 received an indication of cancer during PSA screening (most of whom then had a biopsy); of those, 3 had to be hospitalized for biopsy complications; 35 were diagnosed with prostate cancer (and thus the false alarm rate from the original PSA screening was >85%); of those 35, 3 avoided metastatic prostate cancer and 1 avoided death by prostate cancer while 9 developed impotence or urinary incontinence due to their treatment and 5 died due to prostate cancer despite being treated. In their 2018 recommendations, the USPSTF estimates that 20%-50% of men diagnosed with prostate cancer following a positive PSA screening have cancer that, even if not treated, would never grow, spread, or harm them
Most North American medical groups recommend individualized decisions about screening, taking into consideration the risks, benefits, and the patients' personal preferences.
Screening studies for lung cancer have only been done in high risk populations, such as smokers and workers with occupational exposure to certain substances.In the 2010s recommendations by medical authorities are turning in favour of lung cancer screening, which is likely to become more widely available in the advanced economies.
In December 2013 the U.S. Preventative Services Task Force (USPSTF) changed its long-standing recommendation that there is insufficient evidence to recommend for or against screening for lung cancer to the following: "The USPSTF recommends annual screening for lung cancer with low-dose computed tomography in adults ages 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery".
Early detection of pancreatic cancer biomarkers was accomplished using SERS-based immunoassay approach.A SERS-base multiplex proteinbiomarker detection platform in a microfluidic chip to detect is used to detect several protein biomarkers to predict the type of disease and critical biomarkers and increase the chance of diagnosis between diseases with similar biomarkers (PC, OVC, and pancreatitis). It is generally agreed that general screening of large groups for pancreatic cancer is not at present likely to be effective, and outside clinical trials there are no programmes for this. The European Society for Medical Oncology recommends regular screening with endoscopic ultrasound and MRI/CT imaging for those at high risk from inherited genetics, in line with other recommendations, which may also include CT.
The US Preventive Services Task Force (USPSTF) in 2013 found that evidence was insufficient to determine the balance of benefits and harms of screening for oral cancer in adults without symptoms by primary care providers.The American Academy of Family Physicians comes to similar conclusions while the American Cancer Society recommends that adults over 20 years who have periodic health examinations should have the oral cavity examined for cancer. The American Dental Association recommends that providers remain alert for signs of cancer during routine examinations. Oral cancer screening is also recommended by some groups of dental hygienists.
There is insufficient evidence to recommend for or against screening for skin cancer,and bladder cancer. Routine screening is not recommended for testicular cancer, and ovarian cancer.
Full body CT scans are available for cancer screening, but this type of medical imaging to search for cancer in people without clear symptoms can create problems such as increased exposure to ionizing radiation. However, magnetic resonance imaging (MRI) scans are not associated with a radiation risk, and MRI scans are being evaluated for their use in cancer screening. [ citation needed ]There is a significant risk of detection of what has been called incidentalomas - benign lesions that may be interpreted as a cancer and be subjected to potentially dangerous investigations.