Our knowledge of cancer is always expanding. Researchers and healthcare professionals take the knowledge gained from research studies and use it to develop better practices that will help prevent, detect and treat colorectal cancer, as well as improve the quality of life of people with colorectal cancer.
The following information is a selection of research showing promise for colorectal cancer.
Risk reduction
Risk reduction strategies may reduce the chance of developing cancer.
Noteworthy research includes:
- Researchers are continuing to study aspirin for its effectiveness in lowering the risk of colorectal cancer. Studies have suggested that a daily dose of aspirin can help protect against adenomas forming and colorectal cancer developing. People who are considered high-risk for the development of the disease may benefit most from taking aspirin daily (Lancet, PMID* 22440947, PMID 22036019, PMID 20970847; Lancet Oncology, PMID 22440112; Cancer Prevention Research, PMID 21543343; Health Technology Assessment, PMID 20594533; Journal of the National Cancer Institute, PMID 19211452).
- Other nonsteroidal anti-inflammatory drugs(NSAIDs), in addition to aspirin, may also lower the risk of colorectal cancer (Cancer, PMID 21472711; American Journal of Gastroenterology, PMID 21407185). A study has found that long-term use of NSAIDs may improve the effectiveness of aspirin in reducing the risk of developing adenomas, which are associated with a increased risk of developing colorectal cancer (Journal of the National Cancer Institute, PMID 19211442).
- It remains unclear whether statins (drugs used to lower cholesterol) may reduce the risk of colorectal cancer. Some studies have suggested there is a slightly lower risk of colorectal cancer if statins are used in combination with NSAIDs, while other studies have found no association. Further research is needed to determine if there is a link between statins and risk of colorectal cancer (Annals of Epidemiology, PMID 22056480; Cancer, PMID 21472711; Gut, PMID 20660702; American Journal of Gastroenterology, PMID 19809413; PMID 19352344; World Journal of Gastroenterology, PMID 19452574).
- Canadian and international researchers are studying vitamin D intake, which may contribute to a lower risk of colorectal cancer. Studies have suggested that higher levels of vitamin D in the blood may be associated with a lower risk of developing colorectal cancer (Canadian Journal of Public Health, PMID 22032106; European Journal of Cancer, PMID 20843485; Health Technology Assessment, PMID 20594533; International Journal of Cancer, PMID 20473927; British Medical Journal, PMID 20093284; Nutrition and Cancer, PMID 19116875).
- Canadian and international researchers have shown that getting high amounts of calcium from diet or supplements may reduce the risk of colorectal cancer. They have also shown that eating dairy products may lower the risk of developing colorectal cancer. Other studies have found that calcium may lower the risk of recurrence in people with a history of polyps, but that it is not associated with a lower risk of colorectal cancer in the general population. It has also been suggested that the link between eating dairy products and a lower risk of colorectal cancer may be more related to calcium or vitamin D found in dairy products. More research is needed to determine how calcium and eating dairy products may lower the risk of developing colorectal cancer (American Journal of Clinical Nutrition, PMID 22071715; Canadian Journal of Public Health, PMID 22032106; International Journal of Cancer, PMID 21607947; European Journal of Cancer, PMID 20843485; Health Technology Assessment, PMID 20594533; Nutrition and Cancer, PMID 19116875).
- There is some evidence that dietary selenium and folate (folic acid) may reduce the risk of colon cancer. People with high levels of selenium and folate in blood samples had a lower risk of colon cancer compared to those with low levels of selenium and folate (American Journal of Clinical Nutrition, PMID 21270374; Nutrition and Cancer, PMID 19235033).
Screening
Researchers are working to improve screening techniques for colorectal cancer so that it can be detected early, before signs and symptoms are noticed. This is important because when colorectal cancer is detected and treated early, the chances of recovery are better.
Noteworthy research includes:
- The stool DNA test is a promising technology in colorectal cancer screening. This test finds DNA markers in cells that are shed into the stool from precancerous adenomas and cancers in the colon. The stool DNA test is being used in people who are considered average risk for developing colorectal cancer. The stool DNA test may be easier to tolerate than current screening tests because it is non-invasive and does not require bowel preparation or dietary restrictions. This test has a higher degree of sensitivity (detects that cancer is present in people with disease) and specificity (a negative result in people who do not have cancer) for colorectal cancers than other screening tests. Recent changes to this test have made it easier and less costly to perform (Gastroenterology, PMID 22062357; Journal of the National Comprehensive Cancer Network, PMID 20064291).
- Two large European trials found that a flexible sigmoidoscopy can be an effective screening tool for colorectal cancer in people between the ages of 55 and 64 years. A flexible sigmoidoscopy lets the doctor look at the lining of the rectum and lower part of the colon (sigmoid colon) using a flexible tube with a light and lens on the end (an endoscope). The trial found that people who had a flexible sigmoidoscopy test were less likely to develop colorectal cancer or die from it than a group of similar people who didn’t have the screening test. However, the researchers only compared flexible sigmoidoscopy with no screening. They did not compare it with other methods, such as fecal occult blood test (FOBT). More research is needed to determine whether flexible sigmoidoscopy should be used instead of, or along with, FOBT as a screening test (Journal of the National Cancer Institute, PMID 21852264; Lancet, PMID 20430429; Gut, PMID 19671542; European Journal of Cancer, PMID 19665368).
- Virtual colonoscopy uses a computed tomography (CT) scan to create images of the colon without having to insert a colonoscope into the rectum. A virtual colonoscopy (also called CT colonography) is less invasive and more comfortable than a regular colonoscopy. Some disadvantages of this test include exposure to radiation, the CT scan cannot find very small polyps (less than 6 mm) and the person will need a regular colonoscopy if the CT scan finds an abnormality. Studies continue to examine the effectiveness of virtual colonoscopy in screening people for colorectal cancer (AJR: American Journal of Roentgenology,PMID 20966316; American Journal of Gastroenterology, PMID 20842111; Gut, PMID 18852257).
- Studies have looked at the accuracy of capsule endoscopy (also called PillCam colon endoscopy) in detecting colorectal cancers. In this test, the bowel is cleansed (similar to what is done for a regular colonoscopy) and then the person swallows a tiny capsule containing a camera. The camera takes pictures of the colon and rectum until it is passed from the body. Doctors then look at the pictures to see if there are any polyps or abnormalities (Gastrointestinal Endoscopy, PMID 21601200; American Journal of Gastroenterology, PMID 19888198, PMID 19240710). Studies have reported that capsule endoscopy works best to examine the lining of the colon in people who have thoroughly cleansed bowels. However, capsule endoscopy still does not appear to be as good as colonoscopy for detecting polyps or abnormalities (BMC Gastroenterology, PMID 20565828; New England Journal of Medicine, PMID 19605831). Further study is needed to improve the procedure.
- Researchers have developed a new blood test that detects the presence of the biomarker septin 9(SEPT9), which is shed by colorectal tumours. If the results of the blood test are positive for the presence of septin 9, there is a higher chance that the person has colorectal cancer. People who test positive for septin 9 will need to have a follow-up colonoscopy to confirm the results of the blood test. While septin 9 has been approved for use in Canada, it is only available through one private laboratory and is not covered by provincial health plans. A recent study has found that the stool DNA test is more accurate in finding colorectal cancer than testing the blood for septin 9 (Clinical Gastroenterology and Hepatology, PMID 22019796). Researchers have also found that testing the blood for septin 9 and another biomarker called homeobox protein aristaless-like 4(ALX4) may be helpful for finding precancerous conditions of the colon and rectum. Further study is needed to determine the role of septin 9 and other biomarkers (such as ALX4) in colorectal cancer screening (PLoS One, PMID 20140221).
Diagnosis
A key area of research activity involves developing better ways to diagnose and stage colorectal cancer.
Noteworthy research includes:
- Researchers are studying the use of confocal laser endomicroscopy (CLE) to find lesions (areas of abnormal tissue) in the colon and rectum. CLE is a new diagnostic technique that uses a tiny magnifying lens to examine the lining of the intestine and rectum during colonoscopy(Clinical Gastroenterology and Hepatology, PMID 19683597).
- Researchers are also studying virtual colonoscopy as a diagnostic test for colorectal cancer. A large study (called a meta-analysis) found that it may be a useful tool when a diagnosis of colorectal cancer is suspected (Radiology, PMID 21415247).
Prognostic factors
Prognostic factors that may help determine the outcome of the disease are being studied in colorectal cancer. They can be used to predict the chances of recovery or of cancer coming back. Doctors may also use prognostic factors to help them make treatment recommendations.
Noteworthy research includes:
- American researchers have found that people with a history of heavy smoking (12 or more pack years) under the age of 30 were more likely to have a recurrence of colorectal cancer than those who never smoked (Cancer, PMID 20052723).
- People who have a high body mass index (BMI) before a diagnosis of colorectal cancer may have a less favourable prognosis (Journal of Clinical Oncology, PMID 22124093).
- A mutation in the BRAF gene can cause cancer cells to grow and spread. Some people with colorectal cancer have BRAF gene mutations. People who test positive for this gene mutation are more likely to have aggressive tumours and worse prognosis than people who do not have the gene mutation. Tests for this gene mutation may be helpful in determining course of treatment and follow-up (Journal of Clinical Oncology, PMID 21646616, PMID 20008640; British Journal of Cancer, PMID 20485284; International Journal of Cancer, PMID 19908233).
- Scientists are investigating whether gene expression profiling using DNA microarrays is a reliable way to predict the outcome of colorectal cancer. Microarrays allow scientists to quickly and accurately analyze many genes at one time using specialized equipment. Gene expression profiling can be used to predict the likelihood that the cancer will come back (recur) after treatment and which people are most likely to benefit from adjuvant therapy. Coloprint is a microarray-based gene expression profiling test that is being studied in people with stage II and stage III colorectal cancer (Journal of Clinical Oncology, PMID 21098318; ASCO**, Abstract 358, Abstract 602).
- People with metastatic colorectal cancer are surviving longer than before. Removal of part of the liver for people whose cancer has spread to the liver and advances in treatment, such as targeted therapy and chemotherapy, may have contributed to better survival rates over the last 20 years (Journal of Clinical Oncology,PMID 19470929).
Treatment
Researchers are looking for new ways to improve the treatment of colorectal cancer. Advances in cancer treatment and new ways to manage the side effects related to treatment have improved the outlook and quality of life for many people with cancer.
Noteworthy research includes:
- Researchers are studying robotic surgery, a type of laparoscopic surgery, in people with colorectal cancer. The surgeon sits near the operating table and controls robotic arms that perform the operation through several small incisions in the abdomen and pelvis. This type of surgery has become common for removing the prostate. The technology of wristed instruments (instruments mounted on a “wrist-like” machine) makes this approach technically easier than the laparoscopic approach (Surgical Endoscopy, PMID 21858568; Annals of Surgical Oncology, PMID 20567918; World Journal of Surgery, PMID 20458584; Annals of Surgery, PMID 20395863).
- In addition to looking for new drugs, clinical trials for colorectal cancer are looking into the best order for giving existing useful drugs, and whether there is benefit to combining drugs (Lancet Oncology, PMID 21903473). (It is sometimes difficult to give drugs in combination because overlapping side effects may mean that the amount of each drug given needs to be lowered.) Clinical trials are excellent opportunities to improve the current standards of care. In many cases, clinical trials allow a person with cancer access to promising drugs, such as the many targeted therapy drugs currently in development.
- TroVax is a cancer vaccine that contains modified vaccinia Ankara (MVA) virus. The virus has been changed to contain the TPBG gene, also known as tumour-associated antigen 5T4. Researchers are investigating this new cancer immunotherapy in people with colorectal cancer. The vaccine creates an immune response against the tumour antigen 5T4, which has been identified in people with colorectal cancer. This treatment tries to boost the person’s immune reaction to fight the disease more effectively by identifying and destroying cancer cells. Researchers are giving TroVax in addition to chemotherapy regimens. They have found that it is safe and well tolerated. Further study is needed to determine its use as a biological treatment for people with colorectal cancer (Human Vaccines, PMID 20975327).
- Intrahepatic chemotherapy is a technique used to treat metastatic colorectal cancer that has spread to the liver. Intrahepatic chemotherapy is a regional chemotherapy. Chemotherapy drugs are given through a tiny catheter placed in the main artery leading into the liver (the hepatic artery). This type of regional chemotherapy is called regional hepatic perfusion or hepatic artery infusion.
- Chemoembolization is a type of intrahepatic chemotherapy. A phase III study used tiny beads “loaded” with a drug to treat people with liver metastases. The beads block off the blood supply and deliver chemotherapy directly to the tumour. The beads were loaded with the chemotherapy drug irinotecan (Camptosar) and injected through a catheter placed in the hepatic artery. People who received chemoembolization with irinotecan-loaded beads had improved rates of survival compared to those who received with irinotecan combined with 5-fluorouracil (Adrucil, 5-FU) and folinic acid (leucovorin) (ASCO, Abstract 448).
- Researchers are looking at radioembolization as a way to treat liver metastases in people with colorectal cancer. Radioembolization is radiation therapy using microspheres (such as TheraSphere). Microspheres are tiny glass beads that contain a radioactive isotope, such as yttrium-90. The microspheres are injected into the hepatic artery. They then become stuck in the small blood vessels of the tumour and deliver radiation to the tissue. People with liver metastases from colorectal cancer who do not have any symptoms appear to benefit most from this treatment (Cardiovascular and Interventional Radiology, PMID 21800231, PMID 19680720; American Journal of Clinical Oncology, PMID 21127414; Cancer, PMID 19267416).
- A phase III study looked at 5-fluorouracil systemic chemotherapy, with or without yttrium-90 microsphere radioembolization, as a treatment for colorectal cancer that had spread to the liver and did not respond to previous chemotherapy treatment (chemotherapy-refractory cancer). Researchers found that the combination of 5-fluorouracil and yttrium-90 microsphere radioembolization was associated with a longer period of time before the cancer progressed compared to 5-fluorouracil alone (Journal of Clinical Oncology, PMID 20567019).
Supportive care
Living with cancer can be challenging in many different ways. Supportive care can help people cope with cancer, its treatment and possible side effects.
Noteworthy research includes:
- Peripheral neuropathy, such as numbness or tingling in the toes or fingers, is a side effect of oxaliplatin (Eloxatin). Oxaliplatin is commonly given as part of a chemotherapy regimen to people with advanced colorectal cancer. A small study found that giving the anti-depressant medication venlafaxine (Effexor) may help prevent peripheral neuropathy in people taking oxaliplatin (Annals of Oncology, PMID 21427067).More research is needed before venlafaxine may be recommended as a way to prevent peripheral neuropathy in people with colorectal cancer.
*PMID is the National Library of Medicine PubMed abstract identity number.
**ASCO is the American Society of Clinical Oncology.
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