Yes. According to the National Cancer Institute (NCI), cigarette smoking is linked to an increased risk of colorectal cancer and to an increased risk of dying from colorectal cancer. Smoking is also linked to a higher risk of developing colorectal adenomas, the type of polyp that can turn into cancer over time.
This article walks through what the evidence shows, why some smokers may need earlier or more frequent screening, and what changes after quitting. It does not replace advice from your own doctor.
Warning Signs That Need Prompt Medical Attention
Some symptoms should never wait for a routine appointment. Contact a doctor promptly if you notice:
- Blood in the stool, or stool that looks dark or tarry
- A change in bowel habits that lasts more than a few weeks
- Ongoing abdominal pain, cramping, or bloating that doesn’t go away
- Unexplained weight loss
- Persistent weakness or fatigue
These symptoms have many possible causes, most of them not cancer. Only a doctor can sort out what’s happening.
How Smoking Is Linked to Colorectal Cancer
NCI’s patient-facing summary on colorectal cancer prevention lists cigarette smoking as one of the established risk factors for the disease, alongside age, family history, personal history of certain conditions, inherited gene changes, alcohol use, race, and obesity. Specifically, NCI states that smoking cigarettes is linked to an increased risk of forming colorectal adenomas, and that smokers who have already had adenomas removed face a higher chance of the polyps coming back.
The Centers for Disease Control and Prevention (CDC) frames this in a wider context: smoking harms nearly every organ in the body, not just the lungs. That broader picture is part of why sites like this one cover smoking’s health effects beyond respiratory conditions — see our COPD & respiratory wellness coverage for related material on how smoking affects the body over time.
Other Factors That Raise or Lower Colorectal Cancer Risk
Smoking is one piece of a bigger picture. NCI identifies these factors as part of colorectal cancer risk:
Factors linked to increased risk:
- Age over 50
- Family history of colorectal cancer
- Personal history of colorectal cancer, high-risk adenomas, or inflammatory bowel disease
- Inherited gene changes, such as those linked to familial adenomatous polyposis or Lynch syndrome
- Drinking 3 or more alcoholic beverages a day
- Cigarette smoking
- Obesity
Factors linked to decreased risk (protective):
- Regular physical activity
- Daily aspirin use, only under a doctor’s guidance
- Combination hormone replacement therapy in postmenopausal women, though it does not lower the risk of dying from colorectal cancer
- Removal of colorectal polyps larger than 1 centimeter
NCI also notes that Black individuals have a higher risk of colorectal cancer, and a higher risk of dying from it, compared with other racial groups — even though they aren’t more likely to develop precancerous growths in the first place. This is worth knowing if it applies to you, since it can factor into how your doctor thinks about screening timing.
Why Smokers May Benefit From Earlier or More Frequent Screening
Because smoking adds to overall colorectal cancer risk, and because it’s linked to a higher chance of adenomas recurring after removal, a smoking history is one of the details your doctor may factor into how early you start screening and how often you’re screened. NCI’s patient materials don’t publish a separate screening schedule specifically for smokers — screening age and frequency are personalized based on your full risk picture, which is why this is a conversation to have directly with your doctor rather than a number to look up.
Screening Tests Used to Find Colorectal Cancer
NCI’s patient summary lists five main tests used to screen for colorectal cancer:
- Fecal occult blood test (FOBT): Checks a stool sample for hidden blood. Comes in two forms — guaiac FOBT and immunochemical FOBT, also called FIT.
- Sigmoidoscopy: A thin, lighted tube examines the rectum and lower colon for polyps or abnormal areas.
- Colonoscopy: A similar thin, lighted tube examines the entire rectum and colon, and can remove polyps during the same procedure.
- Virtual colonoscopy (CT colonography): Uses CT imaging to build detailed pictures of the colon without inserting a scope.
- DNA stool test: Checks stool for genetic changes that may signal colorectal cancer.
NCI notes that digital rectal exams have not been shown to reduce colorectal cancer deaths, so they aren’t considered an effective screening method on their own. Every screening option carries some risk — including false results, and physical risks like bleeding or tears in the colon lining with colonoscopy and sigmoidoscopy — which is another reason to talk through the options with your doctor rather than choosing one on your own.
Does Quitting Smoking Lower the Risk?
NCI lists quitting smoking among the general protective actions that may help prevent some cancers, alongside regular exercise and a healthy diet. Its patient materials on colorectal cancer specifically don’t spell out how much risk drops after quitting or how long that takes — that level of detail isn’t part of the patient-facing summary. If you’ve quit or are thinking about it, your doctor can speak to what it means for your personal risk and screening plan. Our smoking and vaping cessation coverage looks at the tools and programs people use to quit, and our telehealth cessation hub covers how prescription support for quitting can work through virtual care.
A Quick Checklist Before Your Next Screening Conversation
- Write down your smoking history, including if you’ve quit and when
- List any family history of colorectal cancer or polyps
- Note any of the warning signs above, even if they seem minor
- Ask what screening test fits your situation, and when to start
- Ask how often you’ll need to repeat screening going forward
- Bring up any other risk factors above that apply to you
Evidence Limits
NCI’s current patient-facing summary states plainly that cigarette smoking is linked to increased colorectal cancer risk and death. It’s worth knowing that this is a summary of a larger body of research, and individual studies on smoking and colorectal cancer have shown varying strength of association — some report a clear increase in risk, others a smaller or less consistent one. NCI’s summary represents the current expert-reviewed consensus, but it is a summary, not a commitment about any one person’s outcome, and it doesn’t replace an individualized risk assessment from your doctor.
Frequently Asked Questions
Does smoking cause colorectal cancer, or just raise the risk?
NCI describes cigarette smoking as a risk factor linked to increased colorectal cancer risk and increased risk of dying from the disease. A risk factor raises the odds — it doesn’t mean everyone who smokes will develop colorectal cancer, or that everyone who develops it smoked.
At what age should a smoker start colorectal cancer screening?
NCI’s patient materials don’t publish a smoking-specific starting age. Screening timing is personalized based on your full risk profile, so this is a question to bring directly to your doctor.
Does vaping carry the same colorectal cancer risk as cigarette smoking?
The NCI and CDC patient materials referenced here focus on cigarette smoking’s link to colorectal cancer. They don’t address vaping-specific colorectal cancer risk, so that question is best directed to your doctor as the research develops.
How much does quitting smoking lower colorectal cancer risk, and how fast?
NCI lists quitting among general cancer-prevention actions but doesn’t quantify the colorectal-cancer-specific timeline in its patient materials. Ask your doctor how your smoking history factors into your personal risk and screening plan.
Educational Disclaimer
This article is for general education only. It does not diagnose any condition, recommend a specific screening test or schedule for you personally, or replace care from a qualified healthcare provider. If you have symptoms, a family history of colorectal cancer, or questions about your own screening timeline, talk to a doctor who knows your full medical history.