Research in diagnosis and prognosis
A key area of research looks at better ways to diagnose and stage cancer, as well as predict prognosis. A prognosis is the doctor’s best estimate of how cancer will affect someone and how it will respond to treatment. Doctors and people with cancer depend on information gathered from tests used to diagnose cancer and predict its prognosis to help make treatment and care decisions.
Researchers are studying many tests and tools to help diagnose, stage and predict prognosis for different types of cancer.
Tumour marker tests
Biomarkers are molecules present in the body that can be measured within cells, tissue or fluids. Genes, chromosomes and proteins are all biomarkers. Researchers are studying different biomarkers to try to find which ones are helpful at finding cancer or predicting prognosis and response to treatment. Some biomarkers are found in abnormal amounts in people with cancer. For example, a protein may be found in higher than normal amounts, a chromosome that should be there is missing or parts of a chromosome are moved to a different chromosome (called translocation). 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. More than 20 tumour markers are currently used to make cancer treatment decisions. Not everyone with a certain type of cancer will have a high level of a tumour marker that is linked to that cancer. Some types of cancer don’t have any known tumour markers yet. To help understand more about cancer types, researchers are collecting and storing tissue samples from cancerous tumours. This is called tumour banking or biobanking. It allows researchers to study tumours to look at genes, proteins and other features that could potentially be used as tumour markers.
Developing new tumour marker tests can help doctors to find cancer earlier, improve diagnosis and predict prognosis. Tumour marker tests allow doctors to better understand cancer, such as whether it is more or less likely to spread or how it will respond to treatment. Tumour marker tests help doctors choose treatment by identifying targets for targeted therapy drugs. Tumour markers may also be monitored to see how well a treatment is working. Tumour markers and tumour marker tests are part of the growing field of personalized medicine.
Gene-based diagnostic tests
Gene-based tests find differences between normal genes and genes that are changed (mutated) in cancer cells. Genes are pieces of DNA that tell each cell in your body what to do. Doctors sometimes look at DNA, an entire gene or many genes together to see if there are changes. Doctors can use genes that are changed or mutated as tumour markers. Researchers have linked some genetic changes or mutations to cancer, but we are only beginning to uncover the full picture of which genes may or may not be involved. For example, mutations in the BRCA1 and BRCA2 genes are linked to breast cancer and mutations in the EGFR gene are linked to some non–small cell lung cancers.
Microarray analysis is a type of gene-based test that allows researchers to look at many expressed genes together. This test can find genes that are turned on or off because of gene mutations or other genetic changes that may be related to a certain type of cancer. Analyzing many genes at the same time to see which are turned on and which are turned off is called gene expression profiling. New technology, called next generation sequencing (NGS), is becoming the preferred method of detecting mutations in multiple genes at the same time. NGS can detect fused genes, which are formed when there has been an abnormal relocation of parts of genes. Fused genes can lead to uncontrolled production of an abnormal protein, making a cancer more aggressive. These abnormalities are potential targets for new therapies (targeted therapies).
Eventually, researchers hope that more and more gene-based diagnostic tests will help doctors identify the best treatments for specific cancers and that more treatments will be tailored to each person’s cancer.
A liquid biopsy is an exciting alternative to a standard biopsy.
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.
In a standard biopsy, a doctor removes tissue from the body with a procedure that usually involves a needle biopsy but may involve surgery. Doctors then recommend treatments based on what this sample of tissue tells them about the cancer, how aggressive it is and which genes are mutated.
Researchers want to find out if using a liquid biopsy can find cancer as well as a standard biopsy does. Even if it can, a standard biopsy will probably still be used for most people because it gives doctors a lot of useful information about the cancer.
A liquid biopsy may be a good option for someone who isn’t well enough to have a standard biopsy. A liquid biopsy may also be used if there isn’t enough tissue to remove and test or if the tumour is in a place that makes a standard biopsy hard to do. A possible advantage of liquid biopsy may be that it could provide information about the tumour that a standard biopsy can’t. During a standard biopsy, only a small piece of the tumour is removed and tested and so it may not represent all the abnormalities that are present in the cancer. Cancer cells, tumour DNA and other substances released by the tumour that are circulating and detectable in the blood may contain extra information that can’t be gathered from the tissue sample. This information may help find gene mutations, predict prognosis and plan better treatment.
Tumours can develop new genetic changes and mutations as they grow and spread. Liquid biopsies are becoming useful in detecting new mutations that occur in people who stop responding to the initial targeted therapy given. They eliminate the need for another tissue biopsy using more invasive procedures, such as surgery. Knowing about these changes may lead to a better understanding of why a treatment is no longer working or a better understanding of new mutations to target with a different treatment.
A liquid biopsy may be most useful in looking for cancer that has come back as part of follow-up care after treatment has ended. Since tumour DNA may not be found in the blood right after treatment, it’s best to test for tumour DNA a while (such as a few months) after treatment is done.
A robotic biopsy removes cells or tissue to look at under a microscope. A robotic biopsy uses robotic surgery, which is often done by laparoscopy through 5 to 6 small surgical cuts (incisions). In robotic surgery, the doctor sits at a control station close to the operating table, watches a monitor with live video and uses controls to move 2 or 3 robotic arms that are connected to surgical instruments that remove tissue.
Imaging techniques and devices
Imaging tests, such as x-rays, MRIs, ultrasounds and CT scans, are a common way to rule out or confirm many diseases, including cancer. Imaging uses special machines and techniques to create images of the inside of the body to see if it is normal and how well it is working. Imaging is a way for doctors to find the exact location of cancer and to check for cancer that has spread. Information from imaging tests is used to stage cancer and help plan treatment.
Researchers are developing new imaging tests and continue to study current imaging tests to see if they can find better ways to diagnose cancer, predict prognosis and plan treatment.
Virtual endoscopy is an imaging test that uses a CT scan to create images of the inside of a hollow organ, like the intestine. A computer makes a 3D picture of the organ from several images. Doctors can use this 3D view to look at the lining of an organ much like they would during a regular endoscopic procedure, but without having to insert an endoscope. Researchers are looking at virtual endoscopy as a way to diagnose and stage colorectal and lung cancers.
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 can detect breast cancer better than mammography.
Improving nuclear medicine and other imaging techniques that are currently used
Researchers are looking at ways to make current imaging tests better. For example, they are trying to make spiral (multi-slice) CT scanners work faster and improve the quality of the images to give more detail.
Nuclear medicine imaging tests look at changes to molecules inside of the body to help diagnose cancer. It is a type of medical imaging that uses radiopharmaceuticals to look at organs and tissues and see how well they are working. Some nuclear medicine imaging tests that researchers are trying to improve include positron emission tomography (PET) scan and single photon emission computed tomography (SPECT). Both use radiopharmaceuticals and a scanning machine to collect information about molecules in the body. A computer uses this information to create images.
PET scans help find cancer by measuring how much sugar (attached to a radiopharmaceutical) is absorbed by cells. Cancer cells absorb more sugar molecules than normal cells, and do so more quickly than normal cells. Through research, PET scans are getting better at finding smaller and slower-growing cancers.
SPECT is an imaging test most commonly used to see how blood flows, particularly in the heart and the brain. Researchers are looking at how SPECT may be useful in detecting certain types of cancer. For a SPECT, antibodies (attached to a radiopharmaceutical) that find and stick to cancer cells are injected, swallowed or inhaled. Then a SPECT scan can be done to detect the radioactive substance and show where the tumour is.
Lower radiation doses
Many imaging tests, such as CT scans and x-rays, use radiation. Imaging machines that use high doses of radiation, such as CT and nuclear medicine imaging tests, are being used more often than they were in the past. So researchers are trying to develop better guidelines to protect people from medical radiation, such as:
- using these tests only when they are absolutely needed
- using other tests that don’t give off radiation (such as ultrasound) when possible
- tailoring radiation doses to each person based on their size so that as little radiation as possible is used (this is especially important for children)
- keeping track of how much medical radiation you are exposed to over your lifetime
- monitoring better how much radiation the machines deliver
Researchers think these guidelines will help make sure you have the benefit of tests that use medical radiation when you need them but with as little risk as possible.
A description of the extent of cancer in the body, including the size of the tumour, whether there are cancer cells in the lymph nodes and whether the disease has spread from its original site to other parts of the body.
Stages are based on specific criteria for each type of cancer.
The process of determining the extent of cancer in the body based on exams and tests is called staging.
The basic biological unit of heredity passed from parents to a child. Genes are pieces of DNA and determine a particular characteristic of an individual.
The molecules inside the cell that program genetic information. DNA determines the structure, function and behaviour of a cell.
A procedure that uses an endoscope (a thin, tube-like instrument with a light and lens) to examine or treat organs or structures in the body.
Cells or tissue may be removed for examination under a microscope. Doctors may also use endoscopy to control bleeding or remove tumours and foreign bodies.
Specialized endoscopies are named for the organ or structure they examine or treat.
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.
A drug that contains a radioactive substance.
A radiopharmaceutical can be used to diagnose and treat cancer and other diseases.
Also called radioactive drug.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
How can you stop cancer before it starts?
Discover how 16 factors affect your cancer risk and how you can take action with our interactive tool – It’s My Life! Presented in partnership with Desjardins.