What Is Colorectal Cancer?
By Dr. Jaime Mayoral, Colon and Rectal Surgeon at Methodist Hospital
Colorectal cancer is a malignancy that develops in the colon or rectum, which together form the large intestine (the final segment of the gastrointestinal system). Most colorectal cancers begin as noncancerous growths called polyps in the inner lining of the colon or rectum that slowly progress to cancer over time. In the United States, approximately 150,000 people are diagnosed with colorectal cancer annually, and about 50,000 die from the disease each year. Colorectal cancer is the third most commonly diagnosed cancer in both men and women, but ranks as the second leading cause of cancer death overall in the United States. (1)
Why Rates Are Increasing in Younger Populations
The rising incidence of colorectal cancer in younger adults (defined as those under age 50) represents a multifactorial phenomenon driven by birth cohort effects, lifestyle changes, and environmental exposures beginning early in life. In the United States, early-onset colorectal cancer incidence increased from 7.9 to 12.9 cases per 100,000 people between 1988 and 2015—a 63% increase—and now accounts for approximately 14% of all colorectal cancer cases. (2) Based on these numbers, approximately 20,000 people under age 50 will be diagnosed with colorectal cancer each year. (3)
The most important factors affecting the development of colorectal cancer in younger patients are modifiable risk factors – behavioral, physical, or environmental factors that increase the likelihood of developing a disease or condition but can be changed, treated, or controlled. For the development of colorectal cancer, modifiable risk factors include obesity, Western dietary patterns, sugar-sweetened beverages, sedentary behavior, and smoking—all exposures that have increased in younger generations of patients (4). Patients who have a body mass index greater than 30, which is classified as obese, are 1.9 times more likely to develop colon cancer than patients who have a BMI less than 25. Western dietary patterns—characterized by processed meat, red meat, refined grains, and high-fat dairy are all linked to an increased risk of colon cancer. The International Agency for Research on Cancer (IARC) recently reclassified processed meats, such as deli meats, bacon, hot dogs, etc., as Class 1 carcinogens, putting them in the same category as smoking and asbestos. It is important to note that this classification indicates strength of evidence that the aforementioned meats increase risk of cancer, not the magnitude of the risk.
Key Signs and Symptoms
The most common signs and symptoms of colorectal cancer are hematochezia (rectal bleeding), abdominal pain, and altered bowel habits (constipation, diarrhea, or alternating patterns). Additional important symptoms include unexplained iron deficiency anemia, unintentional weight loss, and fatigue (5). Any patient, regardless of age, who has one or more of these symptoms should be referred for a colonoscopy.
Prevention and Screening Recommendations
The best way to reduce the risk of colon cancer is to address modifiable risk factors. Exercise, maintaining a healthy weight, avoiding smoking, and limiting intake of processed meats will collectively reduce one’s risk of colon cancer. For average-risk adults (those without personal or family history of colorectal cancer, inflammatory bowel disease, or genetic syndromes), screening should begin at age 45 years according to the US Preventive Services Task Force. Individuals with increased risk based on family history, such as a parent or sibling diagnosed with colon cancer, should begin screening earlier – at age 40 or 10 years before the family member’s age at diagnosis, whichever is earlier. For example, if a patient’s father was diagnosed with colon cancer at age 47, that patient would get a colonoscopy at age 37.
There are multiple modalities for colon cancer screening. The most common is a colonoscopy, which is a procedure done under sedation that directly looks at the entire colon with a camera. The advantage of a colonoscopy procedure is that any polyps, which sometimes are pre-cancerous lesions, can be biopsied or removed during the procedure. In general, if the colonoscopy is negative, it can be done every 10 years. Other screening modalities include at-home stool tests, in which a sample is collected at home and sent to a lab for testing. At-home tests are more convenient for patients but must be done more frequently (every 3 years), and if they are positive, a colonoscopy is the required next step. (1) It is recommended for individuals to talk with their primary care provider about the options and develop a screening plan that is easiest to stick with.
Implications for Female Patients
Colorectal cancer treatment in young female patients has significant implications for fertility, sexual health, and psychosocial well-being. The most critical concerns include treatment-induced infertility, premature menopause from pelvic radiation, sexual dysfunction, body image distress, and significant psychological impacts that differ substantially from those of older patients. Pelvic radiation, which is used for advanced-stage rectal cancers, can cause premature menopause and infertility in younger females (7). All reproductive-aged women with colorectal cancer should receive fertility preservation counseling before initiating treatment. Another significant but less frequently discussed effect of colorectal cancer treatment is sexual dysfunction. Sexual dysfunction is extremely common after colorectal cancer treatment in young women. Sixty-five percent of young-onset colorectal cancer survivors experience some level of sexual dysfunction, which can include dyspareunia (painful sex), vaginal dryness, decreased sex drive, and body image concerns (7). In addition to the psychological impact of a cancer diagnosis, significant stress can come from the impact that undergoing treatment has on patients’ employment and finances.
If you or a loved one is facing a cancer diagnosis, Methodist Healthcare offers integrated cancer services that bring together expert physicians, advanced treatment options, and supportive resources—all designed to guide you through every step of your cancer journey.
Learn more at www.sahealth.com/cancercare
References
1 – American Cancer Society. Colorectal Cancer Facts & Figures 2023-2025. Atlanta: American Cancer Society; 2023.
2 – N Engl J Med 2022;386:1547-1558 DOI: 10.1056/NEJMra2200869
3 – https://publichealth.jhu.edu/2024/colorectal-cancer-in-younger-people#:~:text=In%20the%20United%20States%2C%20about,the%20last%2020%E2%80%9325%20years.
4 – Jayakrishnan T, Ng K. Early-Onset Gastrointestinal Cancers: A Review. JAMA. 2025;334(15):1373–1385. doi:10.1001/jama.2025.10218
5 – Demb J, Kolb JM, Dounel J, et al. Red Flag Signs and Symptoms for Patients With Early-Onset Colorectal Cancer: A Systematic Review and Meta-Analysis. JAMA Netw Open. 2024;7(5):e2413157. doi:10.1001/jamanetworkopen.2024.13157
6 – Fritz CDL, Otegbeye EE, Zong X, Demb J, Nickel KB, Olsen MA, Mutch M, Davidson NO, Gupta S, Cao Y. Red-flag signs and symptoms for earlier diagnosis of early-onset colorectal cancer. J Natl Cancer Inst. 2023 Aug 8;115(8):909-916. doi: 10.1093/jnci/djad068. PMID: 37138415; PMCID: PMC10407716.
7 – Shandley LM, McKenzie LJ. Recent Advances in Fertility Preservation and Counseling for Reproductive-Aged Women with Colorectal Cancer: A Systematic Review. Dis Colon Rectum. 2019 Jun;62(6):762-771. doi: 10.1097/DCR.0000000000001351. PMID: 30730458.
