Colorectal cancer is one of the most common cancers in the United States and one of the leading causes of cancer death — and when people list what causes it, they name red meat, a low-fiber diet, obesity, a lack of exercise, and family history. Every one of those is a real risk factor. But there is another cause that rarely makes anyone's list, and it is one the United States government put in writing only recently: cigarette smoking. In 2014, colorectal cancer became one of just two cancers newly added to the Surgeon General's list of diseases smoking is proven to cause. Most smokers have never been told. The warning label never mentioned the colon, and the advertising certainly never did.
This piece continues the firm's series on the smoking-caused cancers the public rarely hears about — alongside our guides to liver cancer, kidney cancer, bladder cancer, pancreatic cancer, and esophageal cancer. Colorectal cancer belongs on that list. Below: what colorectal cancer is, why it sits on the Surgeon General's smoking list, the biology that explains it, how large the risk really is, a distinctive fact these cases turn on — the decades-long lag between the smoking and the diagnosis, and the molecular fingerprint that can tie a specific tumor to smoking — the “it was just his diet” defense the tobacco companies raise, and how a smoking-related colorectal cancer claim fits the same liability framework the firm uses in its lung cancer, COPD, and bladder cancer matters.
What Colorectal Cancer Is
Colorectal cancer is cancer of the colon or the rectum — the last several feet of the digestive tract. Most of it begins as a small growth on the inner lining called a polyp. Some polyps are harmless, but certain types — adenomatous polyps and a category called sessile serrated lesions — can slowly turn cancerous over the course of years. That slow progression is exactly why screening colonoscopy works: a polyp found and removed early never becomes a cancer. When a cancer does form and is not caught, it can grow through the wall of the bowel and spread to the lymph nodes and then to the liver and lungs.
The disease is often silent in its early stages. When symptoms appear, they tend to be a change in bowel habits, blood in or on the stool, rectal bleeding, abdominal cramping, unexplained weight loss, or an iron-deficiency anemia that turns up on a routine blood test before anyone suspects a tumor. Caught early and confined to the bowel wall, colorectal cancer is one of the more treatable cancers; caught late, after it has spread, it becomes far more dangerous. Where a tumor falls on that spectrum — and how it behaves afterward — is where, as explained below, the smoking connection matters more than once.
Why Colorectal Cancer Is on the Surgeon General's Smoking List
The link between smoking and colorectal cancer is not a plaintiff's theory. It is the conclusion of the United States government's highest scientific authority on tobacco. The landmark 2014 Surgeon General's report, The Health Consequences of Smoking—50 Years of Progress, formally concluded that the evidence is sufficient to infer a causal relationship between cigarette smoking and colorectal cancer. That report is notable because it added only two cancers to the list after a half-century review of the evidence — liver cancer and colorectal cancer. In other words, colorectal cancer is not an old, well-worn entry; it is one of the most recent and most rigorously vetted additions to the roster of cancers cigarettes are known to cause. The American Cancer Society reaches the same conclusion, stating that people who have smoked for many years are more likely both to develop and to die from colorectal cancer, and the Centers for Disease Control and Prevention counts colorectal cancer among the cancers associated with tobacco use in its national cancer surveillance.
The biology explains why an organ at the far end of the digestive tract is harmed by smoke drawn into the lungs. Cigarette smoke is a mixture of dozens of established carcinogens — including polycyclic aromatic hydrocarbons, heterocyclic amines, and tobacco-specific nitrosamines. Some reach the colon and rectum directly, swallowed in saliva; but more importantly, these compounds are absorbed through the lungs into the bloodstream and carried to the lining of the bowel, where they and their reactive metabolites bind to and damage the DNA of the cells that line the colon and rectum. Smoking is also associated with changes in the gut's bacterial environment and with chronic inflammation — conditions that favor the growth of the polyps that later become cancer. An organ does not have to touch smoke to be harmed by it; the bloodstream delivers the carcinogens everywhere it goes.
How Big Is the Smoking Risk?
Elevated, and larger the longer and heavier the smoking. The most comprehensive measurement is a meta-analysis published in JAMA in 2008 by Botteri and colleagues, which pooled 106 observational studies. Its findings:
- Ever-smokers had about 1.18 times the risk of developing colorectal cancer compared with never-smokers — an 18 percent increase — corresponding to roughly 10.8 extra cases per 100,000 person-years.
- Ever-smokers had about 1.25 times the risk of dying from colorectal cancer — a 25 percent higher mortality — corresponding to roughly 6.0 extra deaths per 100,000 person-years. Smoking raises both the odds of getting the disease and the odds of dying of it.
- There was a clear dose-response relationship with both pack-years and cigarettes per day: the more a person smoked, the higher the risk climbed — the gradient epidemiologists rely on to separate genuine causation from coincidence.
- The increase in incidence became statistically significant only after roughly 30 years of smoking, a timing point that matters enormously in these cases and is explained next.
An 18 percent increase may sound modest next to the many-fold risks smoking carries for lung or laryngeal cancer, but colorectal cancer is so common that even a moderate relative risk translates into a large number of additional cases and deaths every year. A person does not have to develop lung cancer for cigarettes to have caused a life-threatening disease.
A Distinctive Fact: The Decades-Long Lag — and the Molecular Fingerprint
Colorectal cancer cases carry two features that set them apart from many other smoking-disease cases, and both come straight from the science.
The first is timing. Unlike some smoking cancers, where risk rises relatively soon, the excess colorectal cancer risk emerges only after a long lag. The epidemiological literature describes an induction period of roughly three to four decades — on the order of 35 years — between the genotoxic exposure and the diagnosis, which is why the JAMA meta-analysis found the incidence effect became significant only after about 30 years of smoking. Rectal cancer in particular has been tied to smoking of 40 years' duration or longer. Far from weakening a claim, this pattern fits it: these are cases about people who smoked for most of their adult lives, developing a cancer decades later, exactly as the science predicts.
The second feature is more distinctive still: the tumor itself can carry a molecular signature associated with smoking. Colorectal cancers are not all alike. Research on molecularly defined subtypes has found that the smoking association is strongest for tumors with specific molecular features — microsatellite-instability-high (MSI-high) tumors, CpG-island-methylator-phenotype (CIMP) positive tumors, and BRAF-mutated tumors that arise through what pathologists call the serrated pathway. In plainer terms, one of the biological routes to colorectal cancer — the serrated pathway, running through sessile serrated lesions — is the one most tightly linked to cigarettes. When a person's pathology report shows that molecular pattern, it is a piece of evidence pointing toward smoking as a cause rather than away from it. Few other smoking cancers offer that kind of tumor-specific corroboration.
This is the kind of record where the firm's Medical-Legal Expert earns his place. Herb Borroto, M.D., J.D., who holds both a medical degree and a law degree, reads the colonoscopy and pathology reports, the tumor's molecular testing (MSI, BRAF, and related markers), the polyp history, and the smoking record together — recognizing when a tumor's own biology supports the causal story, in a way a purely legal review has no reason to look for and a purely clinical review has no reason to connect to liability.
The “It Was Just His Diet” Defense
Colorectal cancer has several established risk factors, and tobacco defendants know it. Expect the familiar move: point to something other than the cigarettes. He ate red meat. She was overweight. There was a family history. He never exercised. There was inflammatory bowel disease. The argument trades on the fact that diet, obesity, physical inactivity, inherited syndromes, and chronic inflammatory bowel conditions are all genuine drivers of colorectal cancer. It does not end the case.
The reason is that these factors are not mutually exclusive with smoking — they operate alongside it, and the Surgeon General weighed all of them before concluding that smoking is an independent cause of the disease. A cause does not have to be the only cause. In product-liability law, a manufacturer whose product was a substantial contributing factor to an injury does not escape responsibility merely by naming another factor that also played a part. And here the plaintiff often has something concrete to answer the deflection with: the decades-long smoking history the science predicts, the dose-response by pack-years, and — where the pathology shows it — the serrated, BRAF-mutated, or MSI-high molecular profile most closely associated with cigarettes. The presence of diet or family history becomes part of the full picture the jury weighs, not an automatic answer to it.
The Legal Framework
Smoking-related colorectal cancer cases proceed on the same liability theories as other smoking-disease cases against the tobacco industry:
- Negligent design, manufacture, and marketing of cigarettes.
- Strict product liability for an unreasonably dangerous product.
- Failure to warn about the full range of cancers smoking causes — including cancers, like colorectal cancer, of organs far from the lungs and added to the official list only recently.
- Fraud and misrepresentation about the safety and addictiveness of the products.
- Civil conspiracy among manufacturers to suppress and distort health research.
The internal industry records unearthed in prior tobacco litigation — the documents showing what the companies knew about the harms of their product and when — remain central evidence. Our companion piece on how tobacco companies hid the truth walks through that record. Alex Alvarez, the firm's Managing Partner and a Board Certified Civil Trial Lawyer, brings that documentary history together with each client's own smoking and medical records to build the causation case a colorectal cancer claim requires — including the answer to the “it was just his diet” defense described above. The carcinogen science here overlaps closely with the firm's lung cancer cases and its other smoking-caused cancer matters.
What a Colorectal Cancer Case Needs
- Documentation of the diagnosis — the colonoscopy and biopsy or surgical pathology confirming colon or rectal cancer, the location, and the staging.
- Any molecular testing of the tumor — MSI status, BRAF mutation, and related markers — which, where present, can support the smoking causal link.
- A substantial smoking history, measured in pack-years, spanning the decades the science associates with the disease.
- Brand identification — which cigarettes were smoked, and for how long.
- The medical history that bears on the other recognized risk factors — family history and inherited syndromes, inflammatory bowel disease, diet, and weight — so those factors can be accounted for rather than left for the defense to spring.
- Causation testimony from an appropriate expert familiar with the smoking–colorectal cancer literature.
- Documentation of the disease's impact — the surgery, chemotherapy or radiation, any recurrence, the decline, and, in cases brought after a death, the cause-of-death records.
The unglamorous paperwork behind these elements is what carries a case. Our guide to smoking history documentation covers the records that build or break a tobacco claim, and our wrongful death family guide walks through what a family should know when colorectal cancer has taken a loved one.
The Jurisdictions We Serve
The Alvarez Law Firm represents smokers and families in Hawaii, Illinois, Nevada, Oregon, Pennsylvania, and the U.S. Virgin Islands. Each of those jurisdictions has its own filing deadlines, its own substantive law on tobacco product liability, and its own version of the discovery rule — how long after a diagnosis, or a death, a claim must be filed. Because those deadlines are unforgiving and easy to overlook while a family is absorbed in treatment, talk to counsel licensed in the relevant state about how they apply to your situation. Waiting can foreclose options that were available earlier.
Frequently Asked Questions
Does smoking cause colorectal cancer?
Yes. The 2014 Surgeon General's report, The Health Consequences of Smoking—50 Years of Progress, added colorectal cancer to the list of diseases for which the evidence is sufficient to infer a causal relationship with cigarette smoking — one of only two cancers newly added in that report, along with liver cancer. The American Cancer Society states that people who have smoked for many years are more likely both to develop and to die from colorectal cancer than people who never smoked. Carcinogens in cigarette smoke reach the lining of the colon and rectum through the bloodstream, where they damage the DNA of the cells that later become cancer.
How much does smoking raise the risk of colorectal cancer?
Meaningfully, and more the longer a person smoked. The largest analysis, a JAMA meta-analysis by Botteri and colleagues that pooled 106 observational studies, found that ever-smokers had about 1.18 times the risk of developing colorectal cancer and about 1.25 times the risk of dying from it compared with never-smokers, with a clear dose-response by pack-years. Crucially, the increased incidence became statistically significant only after roughly 30 years of smoking — consistent with an induction period of three to four decades between the exposure and the diagnosis. That long lag is why colorectal cancer tends to appear in older, longtime smokers.
Can you file a lawsuit for smoking-related colorectal cancer?
Potentially. A smoking-caused colorectal cancer proceeds on the same product-liability theories as other tobacco-disease claims, including negligent design and marketing, strict product liability, failure to warn, fraud, and civil conspiracy. Because diet, family history, and inflammatory bowel disease are also recognized risk factors, causation has to be developed carefully — but the long smoking history these cases require, and in some cases the tumor's own molecular profile, can point specifically toward smoking. Every jurisdiction has its own filing deadline, so a longtime smoker diagnosed with colorectal cancer, or a family that lost someone to it, should speak with counsel licensed in the relevant state promptly.
If You or a Family Member Has Been Diagnosed
If you have a substantial smoking history and have been diagnosed with colon or rectal cancer — or your family lost a loved one to it — a free, confidential case review is the right next step. The same conversation that produces a viable lung cancer case can produce a viable colorectal cancer case.
- Read about the firm's other smoking-caused cancer cases: Liver Cancer, Kidney Cancer, Bladder Cancer, and Pancreatic Cancer.
- Read the wrongful death family guide: Smokers Wrongful Death Family Guide.
- Learn how the industry concealed the harms: How Tobacco Companies Hid the Truth.
Free case review. No fees unless we recover compensation for you.
Sources
- U.S. Surgeon General — "The Health Consequences of Smoking—50 Years of Progress" (2014), which added colorectal cancer (with liver cancer) to the diseases causally linked to smoking. cdc.gov/tobacco/sgr
- Botteri E, et al. "Smoking and Colorectal Cancer: A Meta-analysis." JAMA, 2008;300(23):2765–2778 — 106 studies; ever-smoker incidence relative risk 1.18 and mortality relative risk 1.25, with a dose-response by pack-years and significance emerging after ~30 years of smoking. pubmed.ncbi.nlm.nih.gov
- American Cancer Society — "Colorectal Cancer Risk Factors," noting that people who have smoked for many years are more likely to develop and to die from colorectal cancer. cancer.org
- Centers for Disease Control and Prevention — "Surveillance for Cancers Associated with Tobacco Use, United States," listing colorectal cancer among tobacco-associated cancers. cdc.gov/mmwr
- Peer-reviewed research on smoking and molecularly defined colorectal cancer subtypes, reporting the strongest associations with MSI-high, CIMP-positive, and BRAF-mutated (serrated-pathway) tumors. British Journal of Cancer