Research in screening and finding cancer early
Cancers that are found early are usually easier to treat and cure. But most types of cancer don’t have screening tests. Breast, cervical, colorectal, lung – these types of cancer have safe and effective screening tests. But could we do more with these tests? How can screening programs be improved – are there better tests that could be developed or should some people have the tests more often? And just imagine how many more lives could be saved if there were screening tests for all types of cancer or a way to screen for several types of cancer at the same time.
Along with trying to figure out how to get more people to use the screening programs that we already have, researchers are trying to improve current tests, lessen any harm from screening and develop new ways to find cancer early. Researchers are also very interested in uncovering what individuals or groups of people are at higher risk of developing cancer so that those people can be tested at an earlier age, tested more often or tested with different tests to find cancer early.
The following are some tests and procedures that researchers are studying to screen for cancer and find cancer early. It often takes many years of studying new tests to learn if they are effective.
Researchers continue to try to find out if the imaging tests that we currently use to help diagnose cancer and plan treatment can find cancer early, especially in people who have a higher than average risk of developing cancer. These imaging tests include:
- CT scan (computed tomography)
- MRI (magnetic resonance imaging)
- PET scan (positron emission tomography)
Researchers are also trying to develop new imaging techniques based on current imaging tests. Breast tomosynthesis is an imaging test similar to mammography. It uses an x-ray machine that moves around the breast and takes pictures. The pictures can be stacked together to make a 3D image of the breast to help doctors find breast cancer. Researchers are trying to find out if breast tomosynthesis is better than mammography for breast cancer screening. Some research has shown that breast tomosynthesis has a lower rate of false positives and may help find smaller breast cancers more easily. A false positive means that the tests shows there is cancer but there isn’t. False-positives lead to unnecessary testing and can cause a lot of worry for the person being tested. Breast tomosynthesis may be especially useful in women with dense breasts where small cancers can be hard to find with regular mammography.
An endoscope is a thin, tube-like instrument with a light and lens. An endoscopy is a procedure that uses an endoscope to let a doctor see inside the body. A virtual endoscopy is an imaging test that uses a CT scan to create images of the inside of an organ. A computer makes a 3D picture of the organ using several CT scan images. Doctors can use the 3D view to look at the lining of an organ much like they would during a regular endoscopy, but without having to insert an endoscope. A virtual endoscopy is more comfortable than a regular endoscopy since the doctor doesn’t have to insert an endoscope into the body.
There are some disadvantages with virtual endoscopy. The procedure exposes you to radiation, it doesn’t always find abnormal areas that are very small and the doctor can’t take a biopsy if they see an abnormal area. This means that if an abnormal area is found, you will need to have another test, such as a regular endoscopy as well as a biopsy if it’s needed.
Specialized endoscopies are named for the organ or structure they examine or treat. Researchers are studying virtual colonoscopy to look for signs of cancer in the colon and rectum. They are also studying virtual bronchoscopy to look at the lungs, trachea (windpipe) and bronchi (the 2 tubes that branch from the trachea) in people who have a high risk of lung cancer.
Researchers are studying capsule endoscopy as a screening test for cancers of the digestive tract. Capsule endoscopy is more comfortable than a regular endoscopy and it doesn’t expose you to radiation like virtual endoscopy.
Capsule endoscopy is done by swallowing a pill (called a capsule). The capsule is about the size of a vitamin and has a light and camera. It takes about 8 hours for the capsule to travel through the body. It leaves the body with stool during a bowel movement. As it moves through the digestive tract, the camera takes thousands of pictures which are sent to a device that you wear on your body. The doctor can download the pictures from the device onto a computer to look for abnormal areas like ulcers or polyps.
Your bowels need to be as empty as possible for capsule endoscopy. So one disadvantage of preparing for this test compared to preparing for a standard endoscopy is that you may need to take more laxatives closer to the time of the test. Also, a capsule endoscopy tends to find fewer abnormal areas than a standard endoscopy.
Scientists are studying capsule endoscopy as a screening test for small intestine cancer and colorectal cancer. But further research is needed to try to improve this technique so that it is better at finding abnormal areas.
Tumour marker tests
Biomarkers are substances that occur naturally in the cells, tissue or fluids of your body. Some biomarkers are found in abnormal amounts in people with cancer and people who have precancerous conditions. Researchers are studying different biomarkers to see which are helpful at finding cancer or predicting prognosis and response to treatment in people with cancer. When biomarkers are used to find or understand more about cancer, they are also called tumour markers.
Some tumour markers are specific to one type of cancer, while others are related to more than one type of cancer. They also help predict which cancers are more or less likely to spread.
Researchers are trying to find out if tumour markers in tissue or cells removed from the body, such as blood, urine, stool, saliva, sputum (mucus that is coughed up from the lungs), exhaled breath, semen and vaginal secretions, can help find cancer early. Researchers are also testing combinations of tumour markers, called panels, to see if any of the combinations are better than using one tumour marker to screen for cancer.
Tumour marker tests allow doctors to understand cancer better and learn how it is likely to behave or respond to treatment in each person. Tumour markers and tumour marker tests are part of the growing field of personalized or precision medicine.
As we discover new tumour markers and learn more about the role our genes play in developing cancer, researchers can use this information to develop better screening tests that look for changes before any other signs or symptoms of cancer start to develop. Knowing this information also helps identify those people who have a higher than average risk of developing cancer and who would therefore benefit the most from screening.
A liquid biopsy tests the blood or other body fluid for cancer. It looks for cancer cells, pieces of tumour DNA (called circulating tumour DNA) and other substances released by the tumour. The test can be done on a sample of blood removed during a blood test. Most research using a liquid biopsy is looking at using this technique instead of a standard biopsy to diagnose cancer or look for cancer that has come back after treatment.
It is possible that a liquid biopsy will someday be used to help find cancer early. But there are many challenges to overcome because people who don’t have symptoms of cancer are unlikely to have high amounts of cancer in the blood. So a test that is sensitive enough to find the smallest amounts of cancer in the blood or other body fluids needs to be developed. The test should also be specific to detecting cancer and no other health conditions to help lower the chance of a misdiagnosis.
Genes and gene-based tests
Gene-based tests find differences between normal genes and genes that are changed, or mutated, in cancer cells. Genes are pieces of DNA that tell each cell in your body how to behave. Doctors sometimes look at single genes or many genes together to see if there are changes. Genes that are changed or mutated are a type of tumour marker that doctors can test for. There are many genetic changes or mutations that researchers have linked to cancer. This includes the mutations in the BRCA1 and BRCA2 genes linked to breast cancer and mutations in the EGFR gene linked to non–small cell lung cancer. And recent research shows that children and young adults who develop cancer have a higher rate of having a gene mutation linked to cancer than adults with cancer.
Microarray analysis is a type of gene-based test that allows researchers to look at many genes together to see which ones are turned on and which ones are turned off. Analyzing many genes at the same time to see which are turned on and which are turned off is called gene expression profiling or multigene panel testing.
Using tumour markers, genes and gene-based tests to try to find cancer early is a part of the growing field called personalized or precision medicine. Find out more about personalized medicine.
Human papillomavirus (HPV) is a group of more than 100 different types of related viruses. Some 14 types of HPV can cause abnormal changes to cells in the cervix, mouth (oral cavity), throat (pharynx), vagina, vulva, penis and anus. These abnormal changes can become precancerous conditions and cancer. An HPV test is a procedure that removes a small sample of cells and tests them for the DNA or RNA of high-risk types of HPV.
The HPV test is most often used as a screening test to find individuals at high risk for cervical cancer and precancerous conditions in the cervix. But the HPV test is not yet used as a part of all cervical cancer screening programs in Canada. Researchers are still trying to find out the best way to use the HPV test as part of cervical cancer screening.
Researchers are also trying to find out how to use the HPV test to find other types of cancer linked to HPV. Finding high-risk types of HPV can help doctors identify people who are most likely to develop precancerous conditions linked to HPV. These people can have follow-up tests to watch for signs of a precancerous condition and then have treatment for it before cancer develops.
Find out more about the HPV test.
A procedure used to x-ray the breast.
Doctors use mammography to look for tumours or cysts (sacs that are usually filled with fluid or semi-solid material) in the breasts.
Different types of mammography include screening mammography and diagnostic mammography.
The x-ray image produced is called a mammogram.
The group of organs that work together to take in food and liquid, break them down, absorb nutrients and pass waste from the body.
The digestive system includes the organs of the gastrointestinal (GI) tract, or digestive tract. The organs of the GI tract are the mouth, pharynx (throat), esophagus, stomach, small intestine and large intestine. The digestive system also includes other organs of digestion, which are the teeth, tongue, salivary glands, liver, pancreas and gallbladder.
Having the potential to develop into cancer.
A precancerous condition can (or is likely to) become cancerous (malignant).
Also called premalignant.
The molecules inside the cell that program genetic information. DNA determines the structure, function and behaviour of a cell.
See ribonucleic acid (RNA).