Colorectal Cancer Screening & Prevention

What Is Colorectal Cancer?

Colorectal cancer is a malignancy that develops in the colon (large intestine) or the rectum, the final portion of the digestive tract. It is the third most commonly diagnosed cancer in the United States among both men and women, with approximately 150,000 new cases and more than 53,000 deaths estimated each year, according to the American Cancer Society (ACS). Despite these numbers, colorectal cancer is one of the most preventable and treatable cancers when detected early through routine screening.

The vast majority of colorectal cancers arise from precancerous growths called adenomatous polyps — small, noncancerous clumps of cells that form on the inner lining of the colon or rectum. Over a period of 10 to 15 years, some of these polyps can undergo a slow transformation from benign tissue to cancerous cells, a process known as the adenoma-carcinoma sequence. This extended timeline creates a critical window of opportunity: if polyps are found and removed during a colonoscopy before they become malignant, colorectal cancer can be prevented entirely.

At Texas Gut Health in Sachse, TX, Dr. Jaison John is a board-certified gastroenterologist who specializes in colorectal cancer screening, prevention, and post-treatment surveillance. Dr. John completed his gastroenterology fellowship at UT Medical Branch, where he served as Chief Fellow, and his internal medicine residency at UT Austin Dell Medical School, where he served as Chief Resident. He holds dual board certifications from the American Board of Internal Medicine in both internal medicine and gastroenterology. For patients in Dallas, Sachse, and the surrounding DFW communities, Dr. John provides the expert, guideline-based care that is essential for staying ahead of this disease.

Colorectal Cancer in Younger Adults

One of the most concerning trends in colorectal cancer epidemiology is the steady rise in diagnoses among younger adults. While overall colorectal cancer rates have been declining in adults over 65 — largely due to increased screening — the incidence in adults under age 50 has been climbing by approximately 1 to 2 percent per year since the mid-1990s, according to the American Cancer Society. Some studies have found even sharper increases in adults in their twenties and thirties.

This trend prompted the American Cancer Society in 2018 to lower its recommended screening starting age from 50 to 45 for average-risk adults. The U.S. Preventive Services Task Force (USPSTF) followed with the same recommendation in 2021. The American College of Gastroenterology (ACG) also endorses screening beginning at age 45.

The reasons behind this increase are not fully understood, but researchers have identified several contributing factors, including rising rates of obesity, sedentary lifestyles, diets high in processed and red meats, and possibly changes in the gut microbiome. What is clear is that younger adults should not assume they are immune to colorectal cancer. Anyone experiencing symptoms such as rectal bleeding, persistent changes in bowel habits, or unexplained abdominal pain should seek evaluation promptly, regardless of age.

Signs and Symptoms

One of the challenges of colorectal cancer is that it often produces no noticeable symptoms in its early stages. Many patients with early-stage colorectal cancer feel entirely well, which is why screening is so critical — it can detect cancer and precancerous polyps before symptoms ever appear. When symptoms do develop, they can vary depending on the size and location of the tumor within the colon or rectum.

Common signs and symptoms of colorectal cancer include:

• Blood in the stool or rectal bleeding — This is one of the most common and recognizable symptoms. Blood may appear bright red on the toilet paper or in the toilet bowl, or it may cause stools to appear dark or tarry. Any rectal bleeding warrants medical evaluation.
• Persistent change in bowel habits — Diarrhea, constipation, or a change in stool consistency (such as narrowing of the stool) that lasts for more than a few weeks may be a warning sign.
• Unexplained weight loss — Losing weight without changes in diet or exercise can be an indicator of several cancers, including colorectal cancer.
• Chronic fatigue or weakness — Persistent tiredness that does not improve with rest may be related to anemia caused by slow, chronic blood loss from a tumor in the colon.
• Abdominal pain or cramping — Ongoing discomfort, bloating, or cramping in the abdomen may indicate a growth that is partially obstructing the bowel.
• Feeling that the bowel does not empty completely — A sensation of incomplete evacuation after a bowel movement, particularly with rectal tumors, is a symptom that should be reported to your doctor.
• Iron-deficiency anemia — A blood test showing low iron levels without an obvious dietary cause may prompt your physician to order a colonoscopy to look for a source of occult (hidden) blood loss in the colon.

It is important to note that many of these symptoms can also be caused by non-cancerous conditions such as hemorrhoids, irritable bowel syndrome, or infections. However, because early detection of colorectal cancer so dramatically improves outcomes, any persistent or unexplained symptom deserves a thorough evaluation by a gastroenterologist.

Risk Factors

While colorectal cancer can develop in anyone, certain factors increase a person's likelihood of developing the disease. Understanding your individual risk profile helps you and your gastroenterologist determine when to begin screening and how often to repeat it. The major risk factors for colorectal cancer include:

• Age — The risk of colorectal cancer increases with age. Although rates are rising in younger adults, the majority of cases are still diagnosed in people over 50. Current guidelines recommend that average-risk individuals begin screening at age 45.
• Family history — Having a first-degree relative (parent, sibling, or child) who has been diagnosed with colorectal cancer or advanced adenomatous polyps significantly increases your risk. If the relative was diagnosed before age 60, or if multiple family members are affected, the risk is even greater. In these cases, screening should begin at age 40 or 10 years before the youngest family member's age at diagnosis, whichever comes first.
• Personal history of polyps — Patients who have previously had adenomatous or serrated polyps removed during colonoscopy are at increased risk for developing new polyps and colorectal cancer. Surveillance colonoscopies at intervals of 1 to 5 years are recommended based on the number, size, and histology of the polyps.
• Inflammatory bowel disease (IBD) — Patients with long-standing Crohn's disease or ulcerative colitis involving the colon have an elevated lifetime risk of colorectal cancer. The ACG recommends surveillance colonoscopy beginning 8 years after the onset of colonic IBD symptoms.
• Hereditary syndromes — Lynch syndrome (hereditary nonpolyposis colorectal cancer, or HNPCC) is the most common inherited colorectal cancer syndrome, accounting for approximately 3 to 5 percent of all cases. Familial adenomatous polyposis (FAP) is a rarer condition in which hundreds to thousands of polyps develop in the colon, with near-certain progression to cancer if untreated. Both conditions require earlier and more frequent screening.
• Obesity — Being overweight or obese is associated with an increased risk of developing and dying from colorectal cancer. This association is stronger in men than in women.
• Smoking — Long-term cigarette smoking is associated with increased incidence and mortality from colorectal cancer. The risk increases with the duration and intensity of smoking.
• Diet — Diets high in red meat (beef, pork, lamb) and processed meats (hot dogs, bacon, deli meats) have been linked to higher colorectal cancer risk. The World Health Organization classifies processed meat as a Group 1 carcinogen and red meat as a Group 2A (probable) carcinogen.
• Sedentary lifestyle — Physical inactivity is associated with increased colorectal cancer risk. Regular moderate-to-vigorous exercise has been shown to reduce risk by 20 to 25 percent.
• Heavy alcohol use — Consuming more than two alcoholic drinks per day for men or one per day for women is associated with higher colorectal cancer risk.
• Race and ethnicity — African Americans have the highest incidence and mortality rates of colorectal cancer among all racial and ethnic groups in the United States. The ACG recommends that African Americans begin screening at age 45, which is now consistent with the general population recommendation.
• Type 2 diabetes — People with type 2 diabetes have an increased risk of colorectal cancer, independent of obesity. Insulin resistance may play a role in promoting tumor growth.

Screening and Early Detection

Screening is the most powerful tool available for preventing colorectal cancer and detecting it at its earliest, most treatable stage. Because colorectal cancer usually develops slowly from precancerous polyps over 10 to 15 years, screening offers a rare opportunity to actually prevent cancer — not just find it early. No other cancer screening test offers this level of prevention.

When to Begin Screening

The American Cancer Society, the USPSTF, and the ACG all recommend that adults at average risk for colorectal cancer begin screening at age 45. For patients with increased risk factors — such as a family history of colorectal cancer, personal history of IBD, or a hereditary syndrome — screening should begin earlier, as outlined above under Risk Factors.

Patients in the Dallas, Sachse, Murphy, Plano, Garland, Wylie, and Rowlett communities can schedule a colon cancer screening consultation with Dr. John at Texas Gut Health to determine the right time to begin.

Colonoscopy: The Gold Standard

Colonoscopy remains the gold standard for colorectal cancer screening. It is the only screening method that allows the physician to both visualize the entire colon and remove precancerous polyps during the same procedure. For average-risk patients with a normal result and no polyps, the recommended screening interval is every 10 years. If polyps are found and removed, follow-up intervals are shortened based on the polyps' characteristics:

• 1 to 2 small tubular adenomas: repeat colonoscopy in 7 to 10 years
• 3 to 4 small tubular adenomas: repeat colonoscopy in 3 to 5 years
• 5 to 10 adenomas, any adenoma 10 mm or larger, or adenomas with villous features or high-grade dysplasia: repeat colonoscopy in 3 years
• More than 10 adenomas: repeat colonoscopy in 1 year
• Serrated polyps: surveillance intervals depend on size, location, and the presence of dysplasia, typically ranging from 1 to 5 years

These surveillance intervals are based on the most current guidelines from the U.S. Multi-Society Task Force on Colorectal Cancer (a joint effort of the ACG, AGA, and ASGE).

Other Screening Options

While colonoscopy is the most comprehensive screening method, other tests are available for patients who are unable or unwilling to undergo colonoscopy. These include stool-based tests such as the fecal immunochemical test (FIT), the guaiac-based fecal occult blood test (gFOBT), and the multi-target stool DNA test (Cologuard). CT colonography (virtual colonoscopy) is also an option. It is important to understand that any positive result on a non-colonoscopy screening test requires a follow-up colonoscopy for definitive evaluation. Dr. John can help you choose the screening approach that is right for your situation.

Stages and Prognosis

The stage at which colorectal cancer is diagnosed is the single most important factor in determining prognosis and treatment options. Staging describes how far the cancer has grown and whether it has spread beyond its site of origin. While formal staging uses a detailed TNM (tumor-node-metastasis) system, the following overview provides a general understanding:

• Stage 0 (Carcinoma in situ): Abnormal cells are found only in the innermost lining (mucosa) of the colon or rectum. This is the earliest possible stage and is often found during routine colonoscopy.
• Stage I: Cancer has grown through the mucosa into the submucosa or the muscle layer of the colon wall, but has not spread to nearby lymph nodes or distant sites.
• Stage II: Cancer has grown through the wall of the colon or rectum and may have invaded nearby tissue, but has not reached the lymph nodes.
• Stage III: Cancer has spread to one or more nearby lymph nodes, regardless of how deeply it has penetrated the colon wall.
• Stage IV: Cancer has spread (metastasized) to distant organs such as the liver, lungs, or peritoneum.

The survival statistics underscore why early detection matters so profoundly. According to the American Cancer Society:

• Localized disease (stages I-II): approximately 91% five-year relative survival rate
• Regional disease (stage III): approximately 72% five-year relative survival rate
• Distant disease (stage IV): approximately 14% five-year relative survival rate

When colorectal cancer is found at the localized stage — before it has spread — more than 9 out of 10 patients survive at least five years. This is precisely why screening is so critical: it catches the disease when it is most curable.

Prevention

Colorectal cancer is among the most preventable of all cancers. Prevention strategies fall into two categories: screening (which can directly prevent cancer by removing precancerous polyps) and lifestyle modifications (which reduce overall risk).

Screening Is Prevention

Unlike most cancer screenings, which aim to detect cancer early, colonoscopy can actually prevent colorectal cancer from developing in the first place. When a gastroenterologist finds and removes precancerous polyps during a colonoscopy, those polyps can never progress to cancer. Studies published in the New England Journal of Medicine have demonstrated that colonoscopy with polypectomy reduces colorectal cancer incidence by 40 to 60 percent and colorectal cancer mortality by 29 to 68 percent. Getting screened on schedule is the single most important step you can take to protect yourself.

Lifestyle Modifications

In addition to screening, the following evidence-based lifestyle changes can meaningfully reduce your colorectal cancer risk:

• Maintain a healthy weight: Obesity is a well-established risk factor. Achieving and maintaining a healthy body mass index (BMI) reduces risk.
• Exercise regularly: Aim for at least 150 minutes of moderate-intensity physical activity per week. Regular exercise has been associated with a 20 to 25 percent reduction in colorectal cancer risk.
• Eat a balanced diet: Emphasize fruits, vegetables, whole grains, and legumes. Limit red meat to no more than 18 ounces per week and minimize consumption of processed meats.
• Limit alcohol consumption: If you drink, limit intake to no more than two drinks per day for men and one drink per day for women.
• Do not smoke: Smoking increases colorectal cancer risk and mortality. Quitting at any age provides health benefits.
• Consider calcium and vitamin D: Some studies suggest that adequate calcium and vitamin D intake may have a protective effect against colorectal cancer, though the evidence is not yet conclusive enough for universal supplementation recommendations.

Aspirin for Chemoprevention

The USPSTF has noted that low-dose aspirin use may reduce the risk of colorectal cancer in certain populations, particularly adults aged 50 to 59 with a 10-year cardiovascular disease risk of 10 percent or greater. However, aspirin carries its own risks, including gastrointestinal bleeding. The decision to use aspirin for cancer prevention should be made on an individual basis in consultation with your physician. Dr. John can help you weigh the potential benefits and risks based on your personal health profile.

Treatment Overview

Treatment for colorectal cancer depends on the stage at diagnosis, the location of the tumor, and the patient's overall health. While a gastroenterologist like Dr. John plays a central role in screening, diagnosis, and post-treatment surveillance, the treatment of colorectal cancer itself is typically managed by a multidisciplinary team that includes a colorectal surgeon, a medical oncologist, and in some cases a radiation oncologist.

Surgery

Surgical removal of the tumor is the primary treatment for most stages of colorectal cancer. For very early cancers (stage 0 or some stage I), polyps containing cancer may be completely removed during colonoscopy. For more advanced tumors, a partial colectomy — surgical removal of the affected segment of the colon along with surrounding lymph nodes — is the standard approach. Many of these surgeries can now be performed using minimally invasive (laparoscopic or robotic) techniques.

Chemotherapy

Chemotherapy uses drugs to kill cancer cells and is commonly used for stage III colorectal cancer (after surgery, to reduce the risk of recurrence) and stage IV disease (to control cancer growth and improve quality of life). The specific chemotherapy regimen depends on the cancer's characteristics and the patient's health status.

Radiation Therapy

Radiation therapy is most commonly used for rectal cancer, either before surgery (to shrink the tumor) or after surgery (to destroy any remaining cancer cells). It is less frequently used for colon cancer.

Immunotherapy and Targeted Therapy

Advances in cancer treatment have expanded options for colorectal cancer patients. Immunotherapy drugs, which help the body's immune system recognize and attack cancer cells, have shown significant promise for tumors with specific genetic features such as microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) status. Targeted therapies that attack specific molecular pathways involved in cancer growth are also used for advanced colorectal cancer.

Dr. John works closely with surgical and oncology teams throughout the DFW area to ensure that patients who receive a colorectal cancer diagnosis at Texas Gut Health are connected with the appropriate specialists promptly and seamlessly.

Living with Colorectal Cancer: Surveillance and Survivorship

For the more than 1.5 million colorectal cancer survivors living in the United States today, the journey does not end with treatment. Ongoing surveillance is essential to monitor for cancer recurrence, detect new polyps, and manage any long-term effects of treatment.

Post-Treatment Surveillance

After surgical treatment for colorectal cancer, guidelines from the ACG and the National Comprehensive Cancer Network (NCCN) recommend a structured surveillance schedule that typically includes:

• Surveillance colonoscopy: A colonoscopy is generally recommended within one year of the surgical resection (or within one year of the pre-operative colonoscopy if the entire colon was not fully evaluated before surgery). If results are normal, the next colonoscopy is typically performed at three years, then every five years thereafter, assuming no new polyps or concerning findings.
• CEA blood tests: Carcinoembryonic antigen (CEA) levels may be monitored every 3 to 6 months for the first 2 to 3 years, then every 6 months for years 3 to 5. Rising CEA levels can be an early indicator of recurrence.
• Imaging studies: CT scans of the chest, abdomen, and pelvis are typically performed annually for the first 3 to 5 years to monitor for distant recurrence.

The Gastroenterologist's Role in Survivorship

Your gastroenterologist remains a key member of your care team even after cancer treatment is complete. At Texas Gut Health, Dr. John provides ongoing surveillance colonoscopies and coordinates with your oncology team to ensure that your follow-up care meets current guideline recommendations. The goal of survivorship care is not only to detect any recurrence as early as possible but also to support your overall digestive health and quality of life.

Frequently Asked Questions