Colon Cancer

Colon cancer is the most common form of GI cancer, and it makes up around 6% of all global cancers. Colon cancer is the 4th most commonly diagnosed cancer worldwide, with approximately 1.14 million new cases per year. When combined with rectal cancer as colorectal cancer (CRC), it is the third most commonly diagnosed cancer and the second leading cause of cancer death globally.

Scientists predict that cases of colorectal cancer will increase to 3.2 million per year by 2040 (an increase of 63%). Incidence rates have been decreasing in high-income countries, largely due to screening, but they are increasing in lower-income countries.

A rising incidence of early-onset colon cancer among younger adults is also emerging as a global concern, particularly in East Asia and high-income regions including the United States, Canada, Australia, and Western Europe. Between 1995 to 2019, the rates of young people being diagnosed under 55 doubled, from 1 in 10 to 1 in 5. Colorectal cancer is now the top cause of cancer-related deaths in men and women combined under age 50.

Colon cancer is one of the most preventable cancers. If caught in its earliest stages, there’s a 90% survival rate.

What is colon cancer?

The colon is part of the large intestine, located between the appendix and the rectum. The colon’s role in the digestive system is to extract water and nutrients from what we eat and drink, and then to form poop. There are several sections to the colon:

Right side: Consists of the cecum, ascending colon, hepatic flexure, and half of the transverse colon.

Left side: Consists of the splenic flexure, other half of the transverse colon, descending colon, sigmoid colon, and rectum.

While many people group them together, colon cancer and rectal cancer are technically two distinct cancers that come with unique treatment approaches.

Types of colon cancer

Almost all colon cancers (up to 98%) are adenocarcinomas. These are cancers that begin in glands that line internal organs and make mucus and other fluids. 

Adenocarcinomas

Most adenocarcinomas in the colon grow from adenomatous polyps (adenomas). Screening for colorectal cancer through a colonoscopy is one way to identify and remove these polyps before they become cancer. Several new technologies—like non-invasive screening tests using stool and blood—are also able to identify if someone has adenomas.

If adenomas are caught and removed, in a pre-cancerous phase or in the earliest stages of becoming cancerous, the disease is very treatable and survival rates are high.

Rare types of colon cancer

A few other very rare types of colon cancer include carcinoid tumors (neuroendocrine), gastrointestinal stromal tumors (GISTs), non-Hodgkin lymphoma, leiomyosarcoma, squamous cell carcinoma, and melanomas. 

Staging colon cancer

If you have colon cancer, you need to know your stage. This helps you understand the size of your tumor, where the cancer is now, and the best treatment plan for your unique situation. 

Colon cancer is staged on a scale from 0-4 (many researchers use roman numerals 0-IV) using the TNM staging system. In general:

• Stage 0 (carcinoma in situ): Abnormal cells are in the inner layer of the colon.
• Stage 1: Cancer is in the submucosa and possibly the muscle layer of the colon.
• Stage 2: Cancer has spread past the muscle layer of the colon but not to lymph nodes.
• Stage 3: Cancer is in at least 1 lymph node.
• Stage 4 (also called “metastatic”): The cancer has spread to distant organs like the liver and/or lungs. It may also be in lymph nodes. 

What causes colon cancer?

Risk factors put you at a higher risk of getting cancer. Some risk factors can be controlled with lifestyle changes, and others cannot. Older age, smoking, and obesity increase your risk of many cancers.

These are scenarios researchers have found that can increase your risk:

• Colon polyps
• Family history of colorectal or other cancers like endometrial, ovarian, stomach, urinary tract, brain, and pancreatic 
• Personal history of colorectal cancer
• Certain genetic syndromes like familial adenomatous polyposis (FAP) and Lynch syndrome
• Inflammatory bowel disease (IBD): Crohn’s and ulcerative colitis

Just because you have a risk factor, that doesn’t mean you will get cancer. 

Can you prevent colon cancer?

Getting screened for colon cancer is the No. 1 way to reduce your risk. Colon cancer is one of the few cancers that can be prevented. There are several FDA-approved screening options:

• Colonoscopy
• Stool-based tests (like FIT and Cologuard)
• Blood-based tests (Shield)
  

It’s important to discuss your screening options with a doctor; each has pros and cons. Not all options are covered by insurance nor are all of them available to patients of every age. 

As with every cancer, there are steps you can take to adopt a healthy lifestyle and reduce your overall cancer risk, such as maintaining a healthy weight, not smoking, and limiting or eliminating alcohol. 

For colorectal cancer specifically, studies have shown that eating a lot of red and processed meats and drinking alcohol increases risk. Many researchers around the world are looking into why there’s been an increase of cancer cases among young adults since the early 1990s, and several are exploring the role of diet and environmental factors.

Learn more about cancer prevention from the American Institute for Cancer Research.

What are some colon cancer statistics? 

Based on GLOBOCAN 2022 data:

• An estimated 1,142,286 people were diagnosed with colon cancer globally, ranking it the 4th most commonly diagnosed cancer worldwide.
• Colon cancer accounts for approximately 5.7% of all new cancer cases globally.
• When combined with rectal cancer as colorectal cancer (CRC), it is the 3rd most commonly diagnosed cancer and the 2nd leading cause of cancer death globally, responsible for 9.3% of all cancer deaths.

According to the World Cancer Research Fund:

• China, the US, and Japan had the highest total number of colorectal cancer cases in 2022.
• Hungary, Slovakia, and Norway have the highest incidence rates in the world among those 45+ (more than 10 times higher than the lowest-burden countries in sub-Saharan Africa).

According to IARC:

• The global burden of colorectal cancer is projected to increase to 3.2 million new cases per year by 2040 (a 63% increase) and 1.6 million deaths per year.
• Incidence rates have been decreasing in high-income countries largely due to effective screening programs, but they are increasing in lower-income countries undergoing economic transition and in younger adults globally.

According to the American Cancer Society:

• The median age at colon cancer diagnosis is 67 in men and 71 in women in the US.
• Globally, median age at diagnosis varies from the late 50s in lower-income countries to the late 60s in high-income countries.
• Early-onset colorectal cancer incidence rates are rising in 27 of 50 countries and territories worldwide — and in 14 of those countries, including the United States, rates are increasing in young adults while stabilizing in those 50 and older, confirming this is a global phenomenon.
• Colorectal cancer is now the leading cause of cancer death in adults under 50 in the United States. Incidence in adults aged 20–49 has risen by 1–2% annually since the mid-1990s, with the pace accelerating to 3% per year from 2013 to 2022.

According to the GBD Study 2019:

• A substantial rise in incidence rates among younger adults (under 50) has been observed globally, particularly in high-income countries. This is a trend running counter to the overall decline in older age groups.
• Since 1994, colorectal cancer incidence in adults younger than 50 has been increasing by approximately 2% per year globally.
  

What are my odds of surviving it?

Colon cancer is highly treatable if caught early. Doctors use what’s called “survival statistics” to understand the likelihood of a patient beating the disease.

According to the National Cancer Institute, 65% of patients are alive five years after a colorectal cancer diagnosis. Survival statistics below are for colorectal cancer (colon and rectal combined) as reported by the National Cancer Institute.

Detailed survival statistics are based on where the cancer is located and if it has spread:

Localized

The cancer hasn’t spread

• 34% of cases
• 91.5% of patients are alive five years after diagnosis

Regional

The cancer spread to nearby lymph nodes

• 37% of cases
• 74.6% of patients are alive five years after diagnosis

Distant

The cancer has spread to lymph nodes and/or organs

• 23% of cases
• 16.2% of patients are alive five years after diagnosis
  

What types of tests should I expect to undergo?

Doctors typically use these tests to diagnose colon cancer:

• Colonoscopy
• Blood tests
• Biopsy
  

Once you’ve been diagnosed, you can expect these tests:

• CT scan
• Chest x-ray
• PET scan
  

Ask your doctor about these additional tests—ideally before you begin treatment.

• Biomarker testing
• Genetic testing
  ‍
  

I’m facing a diagnosis: What are my next steps?

If you’re facing a diagnosis, the GI Cancers Alliance is here for you. 

If you’re newly diagnosed, work with your doctor to create a treatment plan. 

Colon cancer treatment plans may include:

• Surgery 
• Chemotherapy
• Targeted therapy
• Immunotherapy

We strongly encourage you to get a second opinion from another trusted doctor so you feel confident moving forward.