Kidney & Colon Cancer

What is Kidney Cancer?

To understand more about kidney cancer, it helps to know about the normal structure and function of the kidneys.

About the kidneys

The kidneys are a pair of bean-shaped organs, each about the size of a fist and weighing about 4 to 5 ounces. They are fixed to the upper back wall of the abdominal cavity, one on either side of the spine. Both are protected by the lower ribcage.

The kidneys’ main job is to filter the blood to remove excess water, salt, and waste products. These substances become urine. Urine travels from the kidneys to the bladder through long slender tubes called ureters. The place where the ureter meets the kidney is called the renal pelvis. The urine is stored in the bladder until you urinate (pee).

The kidneys also help make sure the body has enough red blood cells. They do this by making a hormone called erythropoietin, which tells the bone marrow to make more red blood cells.

Our kidneys are important, but we actually need less than one complete kidney to function. Many people in the United States are living normal healthy lives with just one kidney. Some people may not have any working kidneys at all, and survive with the help of a medical procedure called dialysis. The most common form of dialysis uses a specially designed machine that filters blood much like a real kidney would.

Renal cell carcinoma

Renal cell carcinoma (RCC), also known as renal cell cancer or renal cell adenocarcinoma, is by far the most common type of kidney cancer. About 9 out of 10 kidney cancers are renal cell carcinomas.

Although RCC usually grows as a single mass (tumor) within a kidney, sometimes there are 2 or more tumors in one kidney or even tumors in both kidneys at the same time. Some of these cancers are noticed only after they have become quite large, but most are found before they metastasize (spread) to distant organs in the body. Often they are found on CT scans or ultrasounds that are being done for concerns other than kidney cancer. Like most cancers, RCC is hard to treat once it has spread.

There are several subtypes of RCC, based mainly on how the cancer cells look under a microscope. Knowing an RCC subtype can be a factor in deciding treatment and can also help your doctor determine if your cancer may be due to an inherited genetic syndrome.

Clear cell renal cell carcinoma

This is the most common form of renal cell carcinoma. About 7 out of 10 people with renal cell carcinoma have this kind of cancer. When seen under a microscope, the cells that make up clear cell RCC look very pale or clear.

Papillary renal cell carcinoma

This is the second most common subtype – about 1 case in 10 is this type. These cancers form little finger-like projections (called papillae) in some, if not most, of the tumor. Some doctors call these cancers chromophilic because the cells take in certain dyes and look pink under the microscope.

Chromophobe renal cell carcinoma

This subtype accounts for about 5% (5 cases in 100) of RCCs. The cells of these cancers are also pale, like the clear cells, but are much larger and have certain other features that can be recognized.

Collecting duct renal cell carcinoma

This subtype is very rare. The major feature is that the cancer cells can form irregular tubes.

Unclassified renal cell carcinoma

Rarely, renal cell cancers are labeled as unclassified because the way they look doesn’t fit into any of the other categories or because there is more than one type of cell present.

Other cancerous kidney tumors

Other types of kidney cancers include transitional cell carcinomas, Wilms tumors, and renal sarcomas.

Transitional cell carcinoma

Of every 100 cancers in the kidney, about 5 to 10 are transitional cell carcinomas, also known as urothelial carcinomas. Transitional cell carcinomas don’t start in the kidney itself, but instead begin in the lining of the renal pelvis (where the urine goes before it enters the ureter). This lining is made up of cells called transitional cells that look like the cells that line the bladder. When cancer develops from these cells they look like other urothelial carcinomas, such as bladder cancer, under the microscope. Studies have shown that, like bladder cancer, these cancers are often linked to cigarette smoking and being exposed to certain cancer-causing chemicals in the workplace.

People with transitional cell carcinoma often have the same signs and symptoms as patients with renal cell cancer − blood in the urine and, sometimes, back pain.

These cancers are usually treated by surgically removing the whole kidney and the ureter, as well as the portion of the bladder where the ureter attaches. Smaller, less aggressive cancers can sometimes be treated with less surgery. Chemotherapy (chemo) is sometimes given after surgery, depending on how much cancer is found. The chemo given is the same as that used for bladder cancer. It’s important to talk with your doctor to be aware of your options and the benefits and risks of each treatment.

About 9 out of 10 transitional cell carcinomas of the kidney are curable if they are found at an early stage. The chances for cure drop dramatically if the tumor has grown into the ureter wall or main part of the kidney or if it has a more aggressive (high grade) appearance when seen under a microscope.

After treatment, follow-up visits to your doctor for monitoring with cystoscopy (looking into the bladder with a lighted tube) and imaging tests are extremely important because transitional cell carcinoma can come back in the bladder, as well as other places in the body.
For more information about transitional cell carcinoma, see our document, Bladder Cancer.

Wilms tumor (nephroblastoma)

Nephroblastomas, more commonly called Wilms tumors, almost always occur in children. This type of cancer is very rare among adults. To learn more about this type of cancer, see our document, Wilms Tumor.

Renal sarcoma

Renal sarcomas are a rare type of kidney cancer (less than 1% of all kidney tumors) that begin in the blood vessels or connective tissue of the kidney. Sarcomas are discussed in more detail in our document, Sarcoma- Adult Soft Tissue Cancer.

Benign (non-cancerous) kidney tumors

Some kidney tumors are benign (non-cancerous). This means they do not metastasize (spread) to other parts of the body, although they can still grow and cause problems. Benign kidney tumors include renal cell adenomas, renal oncocytomas, and angiomyolipomas. They can be treated by removing or destroying the tumor, using many of the procedures that are also used for kidney cancers, such as radical nephrectomy, partial nephrectomy, radiofrequency ablation, and arterial embolization. The choice of treatment is influenced by many factors, such as the size of the tumor and if it is causing any symptoms, the number of tumors, whether tumors are present in both kidneys, and the patient’s general health.

Renal adenoma

Renal adenomas are the most common benign kidney tumors. They are small, slow-growing tumors that often show up on imaging tests (such as CT scans) when the doctor is looking for something else. Seen with a microscope, they look a lot like low-grade renal cell carcinomas. In rare cases, tumors first thought to be renal adenomas may turn out to be small renal cell carcinomas. Because they are hard to tell apart, suspected adenomas are often treated like renal cell cancers.

Oncocytoma

Oncocytomas are benign kidney tumors that can sometimes grow quite large. As with renal adenomas, it can sometimes be hard to tell them apart from kidney cancers. Because oncocytomas do not normally spread to other organs, surgery often cures them.

Angiomyolipoma

Angiomyolipomas are another rare benign kidney tumor. They often develop in people with tuberous sclerosis, a genetic condition that also affects the heart, eyes, brain, lungs, and skin. These tumors are made up of different types of connective tissues (blood vessels, smooth muscles, and fat). If they aren’t causing any symptoms, they can often just be watched closely. If they start causing problems (like pain or bleeding), they may need to be treated.

The rest of this document focuses on renal cell carcinoma and not transitional cell carcinomas, Wilms tumors, renal sarcomas, or other less common types of kidney tumors.

Last Medical Review: 11/08/2012
Last Revised: 11/08/2012

What are the risk factors for kidney cancer?

A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer.

But risk factors don’t tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And some people who get the disease may not have had any known risk factors. Even if a person with kidney cancer has a risk factor, it is often very hard to know how much that risk factor contributed to the cancer.

Scientists have found several risk factors that could make you more likely to develop kidney cancer.

Lifestyle-related and job-related risk factors

Smoking

Smoking increases the risk of developing renal cell carcinoma. The increased risk seems to be related to how much you smoke. The risk drops if you stop smoking, but it takes many years to get to the risk level of someone who never smoked.

Obesity

People who are very overweight have a higher risk of developing renal cell cancer. Some doctors think obesity is a factor in about 2 out of 10 people who get this cancer. Obesity may cause changes in certain hormones that can lead to renal cell carcinoma.
Workplace exposures

Many studies have suggested that workplace exposure to certain substances increases the risk for renal cell carcinoma. Some of these substances are asbestos, cadmium (a type of metal), some herbicides, benzene, and organic solvents, particularly trichloroethylene.
Genetic and hereditary risk factors

Some people inherit a tendency to develop certain types of cancer. The DNA that you inherit from your parents may have certain changes that give you this tendency to develop cancer. Some rare inherited conditions can cause kidney cancer. It is important that people who have hereditary causes of renal cell cancer see their doctors frequently, particularly if they have already had a renal cell cancer diagnosed. Some doctors recommend regular imaging tests (such as CT scans) for these people.

People who have the conditions listed here have a much higher risk for getting kidney cancer, although they account for only a small portion of cases overall:

von Hippel-Lindau disease

People with this condition often develop several kinds of tumors and cysts (fluid-filled sacs) in different parts of the body. They have an increased risk for developing clear cell renal cell carcinoma, especially at a younger age. They may also have benign tumors in their eyes, brain, spinal cord, pancreas and other organs; and a type of adrenal gland tumor called pheochromocytoma. This condition is caused by mutations (changes) in the VHL gene.

Hereditary papillary renal cell carcinoma

People with this condition have inherited a tendency to develop one or more papillary renal cell carcinomas, but they do not have tumors in other parts of the body, as is the case with the other inherited conditions listed here. This disorder is linked to changes in many genes, most often the MET gene.

Hereditary leiomyoma-renal cell carcinoma

People with this syndrome develop smooth muscle tumors called leiomyomas (fibroids) of the skin and uterus (in women) and have a higher risk for developing papillary renal cell cancers. It has been linked to changes in the fumarate hydratase (FH) gene.

Birt-Hogg-Dube (BHD) syndrome

People with this syndrome develop many small benign skin tumors and have an increased risk of developing different kinds of kidney tumors, including renal cell cancers and oncocytomas. They may also have benign or malignant tumors of several other tissues. The gene linked to BHD is known as folliculin (FLCN).

Familial renal cancer

People with this syndrome develop tumors called paragangliomas of the head and neck region, as well as tumors known as pheochromocytomas of the adrenal glands and other areas. They also tend to get kidney cancer in both kidneys before age 40. It is caused by defects in the genes SDHB and SDHD (succinate dehydrogenase subunit B and D, respectively).

These gene defects can also cause something called Cowden-like syndrome. People with this syndrome have a high risk of breast, thyroid and kidney cancers.

Hereditary renal oncocytoma

Some people inherit the tendency to develop a kidney tumor called oncocytoma, which has a very low potential for being malignant.

Other risk factors

Family history of kidney cancer

People with a strong family history of renal cell cancer (without one of the known inherited conditions listed previously) also have a 2 to 4 times higher chance of developing this cancer. This risk is highest in brothers or sisters of those with the cancer. It’s not clear whether this is due to shared genes or something that both people were exposed to in the environment − or both.
High blood pressure

The risk of kidney cancer is higher in people with high blood pressure. Some studies have suggested that certain medicines used to treat high blood pressure may raise the risk of kidney cancer, but it is hard to tell if it’s the condition or the medicine (or both) that may be the cause of the increased risk.

Certain medicines

Phenacetin, once a popular non-prescription pain reliever, has been linked to renal cell cancer in the past. Because this medicine has not been available in the United States for over 20 years, this no longer appears to be a major risk factor.

Diuretics: Some studies have suggested that diuretics (water pills) may be linked to a small increase in the risk of renal cell carcinoma. It is not clear whether the cause is the drugs or the high blood pressure they treat. If you need diuretics, you should take them. You shouldn’t avoid them to try to reduce the risk of kidney cancer.

Advanced kidney disease

People with advanced kidney disease, especially those needing dialysis, have a higher risk of renal cell carcinoma. Dialysis is a treatment used to remove toxins from your body if the kidneys do not work properly.

Gender

Renal cell carcinoma is about twice as common in men as in women. Men are more likely to be smokers and are more likely to be exposed to cancer-causing chemicals at work, which may account for some of the difference.

Race

African Americans have a slightly higher rate of renal cell cancer. The reasons for this are not clear.

Last Medical Review: 11/08/2012
Last Revised: 11/08/2012
This articles content was taken from the American Cancer Society website

© 2012 American Cancer Society, Inc. All rights reserved. The American Cancer Society is a qualified 501(c)(3) tax-exempt organization. Cancer.org is provided courtesy of the Leo and Gloria Rosen family.

What is colorectal cancer?

Colorectal cancer is cancer that starts in the colon or the rectum. These cancers can also be referred to separately ascolon cancer or rectal cancer, depending on where they start. Colon cancer and rectal cancer have many features in common. They are discussed together in this document except for the section about treatment, where they are discussed separately.

The normal digestive system

The colon and rectum are parts of the digestive system, which is also called the gastrointestinal (GI) system (see illustration). The first part of the digestive system (the stomach and small intestine) processes food for energy while the last part (the colon and rectum) absorbs fluid to form solid waste (fecal matter or stool) that then passes from the body. To understand colorectal cancer, it helps to know something about the normal structure of the digestive system and how it works.

After food is chewed and swallowed, it travels through the esophagus to the stomach. There it is partly broken down and then sent to the small intestine, also known as the small bowel. It is called the small intestine because it is narrower than the large intestine (colon and rectum). Actually the small intestine is the longest segment of the digestive system — about 20 feet. The small intestine continues breaking down the food and absorbs most of the nutrients.

The small intestine joins the large intestine (or large bowel) in the right lower abdomen. Most of the large intestine is made up of the colon, a muscular tube about 5 feet long. The colon absorbs water and salt from the food matter and serves as a storage place for waste matter.

The colon has 4 sections:

  • The first section is called the ascending colon. It starts with a small pouch (the cecum) where the small bowel attaches to the colon and extends upward on the right side of the abdomen. The cecum is also where the appendix attaches to the colon.
  • The second section is called the transverse colon since it goes across the body from the right to the left side in the upper abdomen.
  • The third section, called the descending colon, continues downward on the left side.
  • The fourth and last section is known as the sigmoid colon because of its “S” or “sigmoid” shape.

The waste matter that is left after going through the colon is called feces or stool. It goes into the rectum, the final 6 inches of the digestive system, where it is stored until it passes out of the body through the anus.

The wall of the colon and rectum is made up of several layers (see the illustration in the staging section). Colorectal cancer starts in the innermost layer and can grow through some or all of the other layers. Knowing a little about these layers is important, because the stage (extent of spread) of a colorectal cancer depends to a great degree on how deeply it grows into these layers. For more detailed information, please see the section, “How is colorectal cancer staged?

Abnormal growths in the colon or rectum

Most colorectal cancers develop slowly over several years. Before a cancer develops, a growth of tissue or tumor usually begins as a non-cancerous polyp on the inner lining of the colon or rectum. A tumor is abnormal tissue and can be benign (not cancer) or malignant (cancer). A polyp is a benign, non-cancerous tumor. Some polyps can change into cancer but not all do. The chance of changing into a cancer depends upon the kind of polyp:

  • Adenomatous polyps (adenomas) are polyps that can change into cancer. Because of this, adenomas are called a pre-cancerous condition.
  • Hyperplastic polyps and inflammatory polyps, in general, are not pre-cancerous. But some doctors think that some hyperplastic polyps can become pre-cancerous or might be a sign of having a greater risk of developing adenomas and cancer, particularly when these polyps grow in the ascending colon.

Another kind of pre-cancerous condition is called dysplasia. Dysplasia is an area in the lining of the colon or rectum where the cells look abnormal (but not like true cancer cells) when viewed under a microscope. These cells can change into cancer over time. Dysplasia is usually seen in people who have had diseases such as ulcerative colitis or Crohn’s disease for many years. Both ulcerative colitis and Crohn’s disease cause chronic inflammation of the colon.

Start and spread of colorectal cancer

If cancer forms in a polyp, it can eventually begin to grow into the wall of the colon or rectum. When cancer cells are in the wall, they can then grow into blood vessels or lymph vessels. Lymph vessels are thin, tiny channels that carry away waste and fluid. They first drain into nearby lymph nodes, which are bean-shaped structures containing immune cells that help fight against infections. Once cancer cells spread into blood or lymph vessels, they can travel to nearby lymph nodes or to distant parts of the body, such as the liver. Spread to distant parts of the body is called metastasis.

Types of cancer in the colon and rectum

Several types of cancer can start in the colon or rectum.

Adenocarcinomas: More than 95% of colorectal cancers are a type of cancer known as adenocarcinomas. These cancers start in cells that form glands that make mucus to lubricate the inside of the colon and rectum. When doctors talk about colorectal cancer, this is almost always what they are referring to.

Other, less common types of tumors may also start in the colon and rectum. These include:

Carcinoid tumors: These tumors start from specialized hormone-producing cells in the intestine. They are discussed in our document, Gastrointestinal Carcinoid Tumors.

Gastrointestinal stromal tumors (GISTs): These tumors start from specialized cells in the wall of the colon called the interstitial cells of Cajal. Some are benign (non-cancerous); others are malignant (cancerous). These tumors can be found anywhere in the digestive tract, but they are unusual in the colon. They are discussed in our document, Gastrointestinal Stromal Tumors (GIST).

Lymphomas: These are cancers of immune system cells that typically start in lymph nodes, but they may also start in the colon, rectum, or other organs. Information on lymphomas of the digestive system is included in our document, Non-Hodgkin Lymphoma.

Sarcomas: These tumors can start in blood vessels as well as in muscle and connective tissue in the wall of the colon and rectum. Sarcomas of the colon or rectum are rare. They are discussed in our document, Sarcoma – Adult Soft Tissue Cancer.

The remainder of this document focuses only on adenocarcinoma of the colon and rectum.

Last Medical Review: 05/24/2012
Last Revised: 11/05/2012
This articles content was taken from the American Cancer Society website

© 2012 American Cancer Society, Inc. All rights reserved. The American Cancer Society is a qualified 501(c)(3) tax-exempt organization. Cancer.org is provided courtesy of the Leo and Gloria Rosen family.

What are the risk factors for colorectal cancer?

A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lungs, larynx (voice box), mouth, throat, esophagus, kidneys, bladder, colon, and several other organs.

But risk factors don’t tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And some people who get the disease may not have any known risk factors. Even if a person with colorectal cancer has a risk factor, it is often very hard to know how much that risk factor may have contributed to the cancer.

Researchers have found several risk factors that may increase a person’s chance of developing colorectal polyps or colorectal cancer.

Risk factors you cannot change

Age

Younger adults can develop colorectal cancer, but the chances increase markedly after age 50: More than 9 out of 10 people diagnosed with colorectal cancer are at least 50 years old.

Personal history of colorectal polyps or colorectal cancer

If you have a history of adenomatous polyps (adenomas), you are at increased risk of developing colorectal cancer. This is especially true if the polyps are large or if there are many of them.

If you have had colorectal cancer, even though it has been completely removed, you are more likely to develop new cancers in other areas of the colon and rectum. The chances of this happening are greater if you had your first colorectal cancer when you were younger.

Personal history of inflammatory bowel disease

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn’s disease, is a condition in which the colon is inflamed over a long period of time. People who have had IBD for many years often develop dysplasia. Dysplasia is a term used to describe cells in the lining of the colon or rectum that look abnormal (but not like true cancer cells) when seen with a microscope. These cells can change into cancer over time.

If you have IBD, your risk of developing colorectal cancer is increased, and you may need to start being screened for colorectal cancer at an earlier age and be screened on a more frequent basis (see the section, “Can colorectal polyps and cancer be found early?”).
Inflammatory bowel disease is different from irritable bowel syndrome (IBS), which does not increase your risk for colorectal cancer.
Family history of colorectal cancer

Most colorectal cancers occur in people without a family history of colorectal cancer. Still, as many as 1 in 5 people who develop colorectal cancer have other family members who have been affected by this disease.

People with a history of colorectal cancer or adenomatous polyps in one or more first-degree relatives (parents, siblings, or children) are at increased risk. The risk is about doubled in those with only one affected first-degree relative. It is even higher if that relative was diagnosed with cancer when they were younger than 45, or if more than one first-degree relative is affected.

The reasons for the increased risk are not clear in all cases. Cancers can “run in the family” because of inherited genes, shared environmental factors, or some combination of these.

If you have a family history of adenomatous polyps or colorectal cancer, you should talk with your doctor about the possible need to begin screening before age 50. If you have had adenomatous polyps or colorectal cancer, it’s important to tell your close relatives so that they can pass along that information to their doctors and start screening at the right age.

Inherited syndromes

About 5% to 10% of people who develop colorectal cancer have inherited gene defects (mutations) that cause the disease. Often, these defects lead to cancer that occurs at a younger age than is common. Identifying families with these inherited syndromes is important because it lets doctors recommend specific steps, such as screening and other preventive measures when the person is younger.

Several types of cancer can be linked with these syndromes, so it’s important to check your family medical history not just for colon cancer and polyps, but also for any other type of cancer. While cancer in close (first-degree) relatives is most concerning, any history of cancer in more distant relatives is also important. This includes aunts, uncles, grandparents, nieces, nephews, and cousins. People who know they have a family history of cancer or colorectal polyps should discuss this history with their doctor. They may benefit from genetic counseling to review their family medical tree to see how likely it is that they have a family cancer syndrome and a discussion about whether or not gene testing is right for them. People who have an abnormal gene can take steps to prevent colon cancer, such as getting screened at an early age. More information on genetic counseling and testing can be found in the section, “Can colorectal cancer be prevented?”

The 2 most common inherited syndromes linked with colorectal cancers are familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC).

Familial adenomatous polyposis (FAP): FAP is caused by changes (mutations) in the APC gene that a person inherits from his or her parents. About 1% of all colorectal cancers are due to FAP.

People with FAP typically develop hundreds or thousands of polyps in their colon and rectum, usually in their teens or early adulthood. Cancer usually develops in 1 or more of these polyps as early as age 20. By age 40, almost all people with this disorder will have developed cancer if preventive surgery (removing the colon) is not done.

Gardner syndrome is a type of FAP that also has benign (non-cancerous) tumors of the skin, soft connective tissue, and bones.

Hereditary non-polyposis colon cancer (HNPCC): HNPCC, also known as Lynch syndrome, accounts for about 3% to 5% of all colorectal cancers. HNPCC can be caused by inherited changes in a number of different genes that normally help repair DNA damage. (See the section, “Do we know what causes colorectal cancer?” for more details.)

The cancers in this syndrome also develop when people are relatively young, although not as young as in FAP. People with HNPCC may also have polyps, but they only have a few, not hundreds as in FAP. The lifetime risk of colorectal cancer in people with this condition may be as high as 80%.

Women with this condition also have a very high risk of developing cancer of the endometrium (lining of the uterus). Other cancers linked with HNPCC include cancer of the ovary, stomach, small bowel, pancreas, kidney, brain, ureters (tubes that carry urine from the kidneys to the bladder), and bile duct.

For more information on HNPCC, see the sections, “Do we know what causes colorectal cancer?” and “Can colorectal cancer be prevented?”

Turcot syndrome: This is a rare inherited condition in which people are at increased risk of adenomatous polyps and colorectal cancer, as well as brain tumors. There are actually 2 types of Turcot syndrome:

  • One can be caused by gene changes similar to those seen in FAP, in which cases the brain tumors are medulloblastomas.
  • The other can also be caused by gene changes similar to those seen in HNPCC, in which cases the brain tumors are glioblastomas.

Peutz-Jeghers syndrome: People with this rare inherited condition tend to have freckles around the mouth (and sometimes on the hands and feet) and a special type of polyp in their digestive tracts (called hamartomas). They are at greatly increased risk for colorectal cancer, as well as several other cancers, which usually appear at a younger than normal age. This syndrome is caused by mutations in the gene STK1.

MUTYH-associated polyposis: People with this syndrome develop colon polyps which will become cancerous if the colon is not removed. They also have an increased risk of cancers of the small intestine skin, ovary, and bladder. This syndrome is caused by mutations in the gene MUTYH.
Racial and ethnic background

African Americans have the highest colorectal cancer incidence and mortality rates of all racial groups in the United States. The reasons for this are not yet understood.

Jews of Eastern European descent (Ashkenazi Jews) have one of the highest colorectal cancer risks of any ethnic group in the world. Several gene mutations leading to an increased risk of colorectal cancer have been found in this group. The most common of these DNA changes, called the I1307K APC mutation, is present in about 6% of American Jews.

Type 2 diabetes

People with type 2 (usually non-insulin dependent) diabetes have an increased risk of developing colorectal cancer. Both type 2 diabetes and colorectal cancer share some of the same risk factors (such as excess weight). But even after taking these factors into account, people with type 2 diabetes still have an increased risk. They also tend to have a less favorable prognosis (outlook) after diagnosis.

Lifestyle-related factors

Several lifestyle-related factors have been linked to colorectal cancer. In fact, the links between diet, weight, and exercise and colorectal cancer risk are some of the strongest for any type of cancer.

Certain types of diets

A diet that is high in red meats (beef, lamb, or liver) and processed meats (hot dogs and some luncheon meats) can increase colorectal cancer risk. Cooking meats at very high temperatures (frying, broiling, or grilling) creates chemicals that might increase cancer risk, but it’s not clear how much this might contribute to an increase in colorectal cancer risk. Diets high in vegetables, fruits, and whole grains have been linked with a decreased risk of colorectal cancer, but fiber supplements do not seem to help. It’s not clear if other dietary components (for example, certain types of fats) affect colorectal cancer risk.

Physical inactivity

If you are not physically active, you have a greater chance of developing colorectal cancer. Increasing activity may help reduce your risk.
Obesity

If you are very overweight, your risk of developing and dying from colorectal cancer is increased. Obesity raises the risk of colon cancer in both men and women, but the link seems to be stronger in men.

Smoking

Long-term smokers are more likely than non-smokers to develop and die from colorectal cancer. Smoking is a well-known cause of lung cancer, but some of the cancer-causing substances in smoke dissolve into saliva and if swallowed, can cause digestive system cancers like colorectal cancer.

Heavy alcohol use

Colorectal cancer has been linked to the heavy use of alcohol. At least some of this may be due to the fact that heavy alcohol users tend to have low levels of folic acid in the body. Still, alcohol use should be limited to no more than 2 drinks a day for men and 1 drink a day for women.

Factors with uncertain, controversial, or unproven effects on colorectal cancer

Night shift work

Results of one study suggested working a night shift at least 3 nights a month for at least 15 years may increase the risk of colorectal cancer in women. The study authors suggested this might be due to changes in levels of melatonin (a hormone that responds to changes in light) in the body. More research is needed to confirm or refute this finding.

Previous treatment for certain cancers

Some studies have found that men who survive testicular cancer seem to have a higher rate of colorectal cancer and some other cancers. This might be because of the treatments they have received.

Several studies have suggested that men who had radiation therapy to treat prostate cancer might have a higher risk of rectal cancer because the rectum receives some radiation during treatment. Most of these studies are based on men treated in the 1980s and 1990s, and the effect of more modern radiation methods on rectal cancer risk is not clear. There are many possible side effects of prostate cancer treatment that men should consider when making treatment decisions. Some doctors recommend that the risk of rectal cancer should be considered as one of those possible side effects.

The American Cancer Society and several other medical organizations recommend earlier screening for people with increased colorectal cancer risk. These recommendations differ from those for people at average risk. For more information, speak with your doctor and refer to the table in the “Can colorectal polyps and cancer be found early?” section of this document.

Last Medical Review: 05/24/2012
Last Revised: 11/05/2012
This articles content was taken from the American Cancer Society website

© 2012 American Cancer Society, Inc. All rights reserved. The American Cancer Society is a qualified 501(c)(3) tax-exempt organization. Cancer.org is provided courtesy of the Leo and Gloria Rosen family.