If a tumor or abnormal growth (polyp) is found during a colonoscopy, the doctor will usually remove it (polypectomy) if possible, or take a tissue sample (biopsy) for lab testing to check for cancer, with larger tumors sometimes requiring surgery, further scans (like CT or MRI) for staging, and potentially chemotherapy or radiation, depending on the diagnosis. The key immediate steps are removal/biopsy, lab analysis, and then staging and treatment planning.
A change in bowel habits, such as more frequent diarrhea or constipation. Rectal bleeding or blood in the stool. Ongoing discomfort in the belly area, such as cramps, gas or pain. A feeling that the bowel doesn't empty all the way during a bowel movement.
But that's not how doctors — or colonoscopies — work. “Less than 1% of colonoscopies result in a finding of cancer,” says Uppal. “But even if yours is one of them, no one is going to perform an unplanned procedure on you while you're sedated.
Doctors can't always tell if a tumor is cancerous just by looking. Some tumors might look suspicious, but a biopsy is needed for sure.
In most cases, no. Your doctor can't usually tell, simply by looking at a polyp during a colonoscopy, if it's cancerous. But if a polyp is found during your colonoscopy, your doctor will remove it and send it to a lab for a biopsy to check for cancerous or precancerous cells.
Around 75% of colorectal cancers start from adenomatous polyps, and about 80% of all colon polyps are adenomas. But only about 5% of adenomas are actually malignant. The risk of a random, average-size colon polyp becoming cancerous is estimated to be 8% over 10 years and 24% over 20 years.
In this way, the doctor examines your entire large intestine twice. If they find something in the process that they need to remove or treat, this will add extra time. Colon polyps are common: they turn up in about 30% of routine colonoscopies. Although most are benign, it's standard procedure to remove them on sight.
If you are looking for information on symptoms of a specific cancer type, go to our cancer type webpages.
Blood tests, a biopsy, or imaging—like an X-ray—can determine if the tumor is benign or malignant.
Symptoms
See a doctor if symptoms like diarrhea, constipation or bloating don't resolve on their own within a few weeks. Excessive fatigue and losing weight without trying may also be symptoms of colorectal cancer. Contact a doctor immediately if you see blood in your stool.
However, despite their invaluable role in cancer detection, general practitioners typically don't offer official cancer diagnoses. Instead, if cancer is suspected, your PCP will send you to a cancer specialist for more advanced care. This written order to receive care from an oncologist is called a referral.
Often symptomless: Colon cancer starts as polyps and usually develops slowly for 10 to 15 years.
Cancer of the colon is a highly treatable and often curable disease when localized to the bowel. Surgery is the primary form of treatment and results in cure in approximately 50% of patients.
Primary tumors located in the colon — and even those that have spread to other organs — can cause real pain. And patients who have a full-blown obstruction can be in a lot of pain. But those who don't might just experience some mild discomfort or even an occasional crampy feeling.
Symptoms
The tumor is growing aggressively: While benign tumors are usually slow-growing, some can grow quickly and cause serious health problems, prompting the use of chemotherapy.
In some cases, tumors cause symptoms like:
Stage 1 usually means that a cancer is small and contained within the organ it started in. Stage 2 usually means that the tumour is larger than in stage 1 but the cancer hasn't started to spread into the surrounding tissues. Sometimes stage 2 means that cancer cells have spread into lymph nodes close to the tumour.
Incurable cancers are those that current treatments cannot completely eliminate, often because they are advanced (spread) or have returned after initial treatment, but they are not necessarily untreatable; treatments like chemo, radiation, and new targeted therapies aim to control the disease, slow growth, relieve symptoms, and improve quality of life. Common examples of cancers often considered incurable include pancreatic, liver, brain, esophageal, and certain advanced lung cancers, but research continuously offers new hope, with many patients living longer with ongoing management.
It has been demonstrated in animal models that sites of injury are a preferential area for tumor growth and that surgical trauma enhances loco-regional metastases (5). Several experimental trials clearly demonstrate that tumor removal is followed by accelerated tumor growth both locally and at distant sites (4, 6).
An abnormal result means something was found, such as polyps, inflammation or bleeding. The number, size and type of these findings determine when the next colonoscopy should be scheduled.
Symptoms that require an urgent colonoscopy
You will typically receive initial results immediately after your colonoscopy, once the sedation wears off. Your doctor will discuss their findings and provide a written report. If biopsies were taken, you will get these results within a few days to two weeks.