Most colorectal cancers are adenocarcinomas. This is a type of cancer that starts in a specific cell type, like the cells that line the inside of the colon and rectum. Other types of colorectal cancer are possible, such as carcinoid tumors or lymphomas, but these are less common.
Adenocarcinomas usually start as a precancerous growth — called a “polyp” — that protrudes into the inside of the intestine. And with time they can grow into the walls of the intestine and beyond.
Colorectal cancer is the second most common cause of cancer-related death in the U.S. The rate of colorectal cancer has been declining in recent years overall, but it is actually increasing in adults under 50 years of age.
As with many cancers, the exact cause of colorectal cancer isn’t known. But years of research have uncovered many risk factors. These are things that increase your likelihood of developing colorectal cancer.
Risk factors for colorectal cancer include:
Obesity
Not getting enough exercise
Drinking alcohol
Smoking
Eating a lot of red and processed meats
Type 2 diabetes
Age greater than 50 years
African or Ashkenazi heritage
Family history of colorectal cancer or polyps
Personal history of polyps, ulcerative colitis, or Crohn’s disease
Rare, inherited syndromes such as familial adenomatous polyposis or Lynch syndrome
Research is ongoing into why these factors increase the likelihood of colorectal cancer. This will help experts understand the cause(s) and, possibly, how it can be prevented.
It’s important to know that having risk factors doesn’t mean you’re guaranteed to get cancer, and some people with no risk factors will get cancer. Some risk factors can’t be changed, such as your age or family history. But many risk factors are related to lifestyle and can be changed.
The most common signs and symptoms of colorectal cancer include:
Change in bowel habits, such as diarrhea or constipation
Bleeding from the rectum
Bloody or dark black stools
Abdominal pain
Anemia (low red blood cell count)
Fatigue (feeling extra tired and weak)
Unexplained weight loss
Symptoms are usually due to tumor growth into the inside of the colon or nearby structures. In its early stages, colorectal cancer may not cause symptoms. This highlights the importance of screening for colorectal cancer (more on this below). Early detection of colorectal cancer allows for more effective treatment.
Colorectal cancer is typically found in one of three ways:
1) You have signs and symptoms (most common).
2) You don’t have symptoms, but a screening test finds it.
3) It causes a sudden problem, such as gastrointestinal bleeding, that puts you in the hospital.
If you have symptoms, it’s best to see your provider right away. They can help determine the next best step. In most cases, you will be referred for a colonoscopy. This is a procedure that allows a specialist to look inside your rectum and colon with a camera. It also allows them to remove precancerous polyps or small tumors.
If you don’t have symptoms, but you’re 45 years old or older, it’s time for a screening test. Screening tests help look for cancer before they cause symptoms. Colorectal cancer screening tests include:
Colonoscopy: looks inside the entire colon and rectum
Flexible sigmoidoscopy: looks inside the lower third of the colon and rectum
Stool tests: test for blood in your stool
CT or colonography (virtual colonoscopy): uses radiation imaging to create pictures of your colon and rectum
If you have any risk factors for colorectal cancer, you might benefit from a screening test earlier than age 45. Your healthcare provider can guide you through the screening process.
Know that if you don’t have a primary care provider or health insurance, colorectal cancer screening is still available to you.
Treatment for colorectal cancer depends on the stage. For cancer that is localized (hasn’t spread elsewhere), surgery is often curative. Surgery also plays an important role in more advanced cancer. But it’s often combined with medical treatments, such as chemotherapy (FOLFOX) or targeted therapy. When cancer has spread (metastasized) to other organs, surgery may not be an option:
Stage 0: polyp removal via colonoscopy
Stage 1: surgery via colectomy or colonoscopy in some cases
Stage 2: surgery with or without medical treatment
Stage 3: surgery and medical treatment with or without radiation
Stage 4: medical treatment with or without surgery, depending on the location and size of metastases
Surgery involves removing the affected portion of the colon (called a “colectomy”), as well as nearby lymph nodes. In most cases, this can be done via a laparoscopic or robotic surgery, which are minimally invasive. These allow for faster recovery. But there is still a role for colectomy through a large abdominal incision, called an “open” colectomy in some cases.
It’s important to know that many people have a stoma after colectomy. After the cancer is removed, the remaining portion of the intestine is rerouted to an opening in the abdominal wall. This allows waste to leave the body in a different way while the colon heals. The stoma may be temporary – the surgeon may reattach the intestine and rectum after a healing period – or permanent.
If you or your loved one has colorectal cancer, you probably have a lot of questions. Living with this type of cancer is certainly an adjustment. Common concerns include:
Living with a stoma
Managing side effects from chemotherapy
Changing eating habits during or after treatment
Dealing with changes in bowel habit
Wondering if treatment will affect intimacy or relationships
Worrying about cancer recurrence
You may not feel comfortable talking about these things with others, especially at first. But don’t be afraid to discuss your concerns with your cancer care team. They’ve heard it all before, and they’re happy to answer any and all questions. They can also direct you to resources to help with nutrition advice, mental health support, various therapies, nursing guidance, and even supplies you need at home. So don’t hesitate to ask for help when you need it.
There’s no proven way to completely prevent colorectal cancer. But knowing your risk factors, and addressing the ones you can change, can certainly help. Also, it helps to know that some factors may decrease the risk of colorectal cancer, including regular physical activity, diets high in fiber, and daily aspirin (for some people).
Some steps you can take to help prevent colorectal cancer include:
Get screened at age 45, or earlier if you have risk factors.
Ask your provider about testing if you have a personal or family history of polyps or colon cancer.
Eat more fruits and vegetables and less meat.
Exercise regularly.
Don’t smoke.
Cut back on alcohol, or don’t drink at all.
Ask your provider if it’s safe to take a daily aspirin.
Many of the lifestyle measures above can also decrease your risk for other cancers and medical conditions, so there’s no harm in trying them. As for aspirin, long-term use (10 years or more) is recommended for adults over 50 years old who don’t have a risk of increased bleeding. Aspirin may not be beneficial if you start taking it after age 70.
Very early. In some cases, precancerous polyps can be removed during colonoscopy. This is why screening is so important. Detecting cancer early — before it causes symptoms — is the best way to improve outcomes.
Yes, colon cancer in early stages can be cured. When colorectal cancer has spread to other organs or tissues, a complete cure is less likely.
Prognosis depends on the stage of the cancer at diagnosis. “Localized” cancer that hasn’t spread has better survival rates than cancer that has spread to nearby organs or lymph nodes. Cancer that has spread to distant parts of the body has the worst prognosis.
Keep in mind that cancer statistics aren’t the whole picture. It’s great to be informed, but try not to get caught up in the numbers.
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