Because of the way familial polyposis develops, it is possible to have the genetic condition, and therefore be at risk, but have no polyps or issues so far. Therefore, an individual may be diagnosed "at risk of" FAP, and require routine monitoring, but not (yet) actually have FAP (i.e., carries a defective gene but as yet appears not to have any actual medical issue as a result of this). Clinical management can cover several areas:

- Identifying those individuals who could be at risk of FAP: usually from family medical history or genetic testing

- Diagnosis (confirming whether they have FAP)—this can be done either by genetic testing, which is definitive, or by visually checking the intestinal tract itself.

- Screening / monitoring programs involve visually examining the intestinal tract to check its healthy condition. It is undertaken as a routine matter every few years where there is cause for concern, when either (a) a genetic test has confirmed the risk or (b) a genetic test has not been undertaken for any reason so the actual risk is unknown. Screening and monitoring allows polyposis to be detected visually before it can become life-threatening.

- Treatment, typically surgery of some kind, is involved if polyposis has led to a large number of polyps, or a significant risk of cancer, or actual cancer.

Screening for colonic polyps as well as preventing them has become an important part of the management of the condition. Medical societies have established guidelines for colorectal screening in order to prevent adenomatous polyps and to minimize the chances of developing colon cancer. It is believed that some changes in the diet might be helpful in preventing polyps from occurring but there is no other way to prevent the polyps from developing into cancerous growths than by detecting and removing them.

According to the guidelines established by the American Cancer Society, individuals who reach the age of 50 should perform an occult blood test yearly. Colon polyps as they grow can sometimes cause bleeding within the intestine, which can be detected with the help of this test. Also, persons in their 50s are recommended to have flexible sigmoidoscopies performed once in 3 to 5 years to detect any abnormal growth which could be an adenomatous polyp. If adenomatous polyps are detected during this procedure, it is most likely that the patient will have to undergo a colonoscopy. Medical societies recommend colonoscopies every ten years starting at age 50 as a necessary screening practice for colon cancer. The screening provides an accurate image of the intestine and also allows the removal of the polyp, if found. Once an adenomatous polyp is identified during colonoscopy, there are several methods of removal including using a snare or a heating device. Colonoscopies are preferred over sigmoidoscopies because they allow the examination of the entire colon; a very important aspect, considering that more than half of the colonic polyps occur in the upper colon, which is not reached during sigmoidoscopies.

It has been statistically demonstrated that screening programs are effective in reducing the number of deaths caused by colon cancer due to adenomatous polyps. While there are risks of complications associated with colonoscopies, those risks are extremely low at approximately 0.35 percent. For comparison, the lifetime risk of developing colon cancer is around 6 percent. As there is a small likelihood of recurrence, surveillance after polyp removal is recommended.

Monitoring involves the provision of outpatient colonoscopy, and occasionally upper gastric tract esophagogastroduodenoscopy (EGD, to search for premalignant gastric or duodenal tumors), typically once every 1–3 years, and/or a genetic blood test to definitively confirm or deny susceptibility. A small number of polyps can often be excised (removed) during the procedure, if found, but if there are more severe signs or numbers, in patient surgery may be required.

NCBI states that when an individual is identified as having FAP, or the mutations resulting in FAP: "It is appropriate to evaluate the parents of an affected individual (a) with molecular genetic testing of APC if the disease-causing mutation is known in the proband [person first identified with the condition] or (b) for clinical manifestations of APC-associated polyposis conditions".

Diet and lifestyle are believed to play a large role in whether colorectal polyps form. Studies show there to be a protective link between consumption of cooked green vegetables, brown rice, legumes, and dried fruit and decreased incidence of colorectal polyps.

Complete removal of a SSA is considered curative.

Several SSAs confer a higher risk of subsequently finding colorectal cancer and warrant more frequent surveillance. The surveillance guidelines are the same as for other colonic adenomas. The surveillance interval is dependent on (1) the number of adenomas, (2) the size of the adenomas, and (3) the presence of high-grade microscopic features.

Colorectal polyps can be detected using a faecal occult blood test, flexible sigmoidoscopy, colonoscopy, virtual colonoscopy, digital rectal examination, barium enema or a pill camera.

Malignant potential is associated with

- degree of dysplasia

- Type of polyp (e.g. villous adenoma):

- Tubular Adenoma: 5% risk of cancer

- Tubulovillous adenoma: 20% risk of cancer

- Villous adenoma: 40% risk of cancer

- Size of polyp:

- <1 cm =<1% risk of cancer

- 1 cm=10% risk of cancer

- 2 cm=15% risk of cancer

Normally an adenoma which is greater than 0.5 cm is treated

Colon polyps are not commonly associated with symptoms. Occasionally rectal bleeding, and on rare occasions pain, diarrhea or constipation may occur because of colon polyps. Colon polyps are a concern because of the potential for colon cancer being present microscopically and the risk of benign colon polyps transforming over time into malignant ones. Since most polyps are asymptomatic, they are usually discovered at the time of colon cancer screening. Common screening methods are occult blood test, colonoscopy, sigmoidoscopy (usually flexible sigmoidoscopy, using a flexible endoscope, but more rarely the older rigid sigmoidoscopy, using a rigid endoscope), lower gastrointestinal series (barium enema), digital rectal examination (DRE), and virtual colonoscopy. The polyps are routinely removed at the time of colonoscopy either with a polypectomy snare (first description by P. Deyhle, Germany, 1970) or with biopsy forceps. If an adenomatous polyp is found with sigmoidoscopy or if a polyp is found with any other diagnostic modality, the patient must undergo colonoscopy for removal of the polyp(s). Even though colon cancer is usually not found in polyps smaller than 2.5 cm, all polyps found are removed since the removal of polyps reduces the future likelihood of developing colon cancer. When adenomatous polyps are removed, a repeat colonoscopy is usually performed in three to five years.

Most colon polyps can be categorized as sporadic.

The serrated polyposis syndrome (SPS) is a relatively rare condition characterized by multiple and/or large serrated polyps of the colon. Diagnosis of this disease is made by the fulfillment of any of the World Health Organization’s (WHO) clinical criteria.

Genetic testing for mutations in DNA mismatch repair genes is expensive and time-consuming, so researchers have proposed techniques for identifying cancer patients who are most likely to be HNPCC carriers as ideal candidates for genetic testing. The Amsterdam Criteria (see below) are useful, but do not identify up to 30% of potential Lynch syndrome carriers. In colon cancer patients, pathologists can measure microsatellite instability in colon tumor specimens, which is a surrogate marker for DNA mismatch repair gene dysfunction. If there is microsatellite instability identified, there is a higher likelihood for a Lynch syndrome diagnosis. Recently, researchers combined microsatellite instability (MSI) profiling and immunohistochemistry testing for DNA mismatch repair gene expression and identified an extra 32% of Lynch syndrome carriers who would have been missed on MSI profiling alone. Currently, this combined immunohistochemistry and MSI profiling strategy is the most advanced way of identifying candidates for genetic testing for the Lynch syndrome.

Genetic counseling and genetic testing are recommended for families that meet the Amsterdam criteria, preferably before the onset of colon cancer.

People with juvenile polyps may require yearly upper and lower endoscopies with polyp excision and cytology. Their siblings may also need to be screened regularly. Malignant transformation of polyps requires surgical colectomy.

The following are the Amsterdam criteria in identifying high-risk candidates for molecular genetic testing:

"Amsterdam Criteria (all bullet points must be fulfilled):"

- Three or more family members with a confirmed diagnosis of colorectal cancer, one of whom is a first degree (parent, child, sibling) relative of the other two

- Two successive affected generations

- One or more colon cancers diagnosed under age 50 years

- Familial adenomatous polyposis (FAP) has been excluded

"Amsterdam Criteria II (all bullet points must be fulfilled):"

- Three or more family members with HNPCC-related cancers, one of whom is a first-degree relative of the other two

- Two successive affected generations

- One or more of the HNPCC-related cancers diagnosed under age 50 years

- Familial adenomatous polyposis (FAP) has been excluded

Most juvenile polyps are benign, however, malignancy can occur. The cumulative lifetime risk of colorectal cancer is 39% in patients with juvenile polyposis syndrome.

There is a risk of development of cancer with fundic gland polyposis, but it varies based on the underlying cause of the polyposis. The risk is highest with congenital polyposis syndromes, and is lowest in acquired causes. As a result, it is recommended that patients with multiple fundic polyps have a colonoscopy to evaluate the colon. If there are polyps seen on colonoscopy, genetic testing and testing of family members is recommended.

In the gastric adenocarcinoma associated with proximal polyposis of the stomach (GAPPS), there is a high risk of early development of proximal gastric adenocarcinoma.

It is still unclear which patients would benefit with surveillance gastroscopy, but most physicians recommend endoscopy every one to three years to survey polyps for dysplasia or cancer. In the event of high grade dysplasia, polypectomy, which is done through the endoscopy, or partial gastrectomy may be recommended. One study showed the benefit of NSAID therapy in regression of gastric polyps, but the efficacy of this strategy (given the side effects of NSAIDs) is still dubious.

Most polyps are benign and do not need to be removed. Polyps larger than 1 cm with co-occurring gallstones occurring in people over the age of 50 may have the gallbladder removed (cholecystectomy), especially if the polyps are several or appear malignant. Laparoscopic surgery is an option for small or solitary polyps.

Polypoid lesions of the gallbladder affect approximately 5% of the adult population. The causes are uncertain, but there is a definite correlation with increasing age and the presence of gallstones (cholelithiasis). Most affected individuals do not have symptoms. The gallbladder polyps are detected during abdominal ultrasonography performed for other reasons.

The incidence of gallbladder polyps is higher among men than women. The overall prevalence among men of Chinese ancestry is 9.5%, higher than other ethnic types.

CT scan can show the full extent of the polyp, which may not be fully appreciated with physical examination alone. Imaging is also required for planning surgical treatment. On a CT scan, a nasal polyp generally has an attenuation of 10–18 Hounsfield units, which is similar to that of mucus. Nasal polyps may have calcification.

Nasal polyps can be seen on physical examination inside of the nose and are often detected during the evaluation of symptoms. On examination, a polyp will appear as a visible mass in the nostril. Some polyps may be seen with anterior rhinoscopy (looking in the nose with a nasal speculum and a light), but frequently, they are farther back in the nose and must be seen by nasal endoscopy. Nasal endoscopy involves passing a small, rigid camera with a light source into the nose. An image is projected onto a screen in the office so the doctor can examine the nasal passages and sinuses in greater detail. The procedure is not generally painful, but the patient can be given a spray decongestant and local anesthetic to minimize discomfort.

Attempts have been made to develop scoring systems to determine the severity of nasal polyps. Proposed staging systems take into account the extent of polyps seen on endoscopic exam and the number of sinuses affected on CT imaging. This staging system is only partially validated, but in the future, may be useful for communicating the severity of disease, assessing treatment response, and planning treatment.

Screening methods for colon cancer depend on detecting either precancerous changes such as certain kinds of polyps or on finding early and thus more treatable cancer. The extent to which screening procedures reduce the incidence of gastrointestinal cancer or mortality depends on the rate of precancerous and cancerous disease in that population. gFOBT (guaiac fecal occult blood test) and flexible sigmoidoscopy screening have each shown benefit in randomized clinical trials. Evidence for other colon cancer screening tools such as iFOBT (immunochemical fecal occult blood test) or colonoscopy is substantial and guidelines have been issued by several advisory groups but does not include randomized studies.

In 2009 the American College of Gastroenterology (ACG) suggest that colon cancer screening modalities that are also directly preventive by removing precursor lesions should be given precedence, and prefer a colonoscopy every 10 years in average-risk individuals, beginning at age 50. The ACG suggests that cancer detection tests such as any type of FOB are an alternative that is less preferred, and if a colonoscopy is declined, the FIT (fecal immunochemical test, or iFOBT) should be offered instead. Two other recent guidelines, from the US Multisociety Task Force (MSTF) and the US Preventive Services Task Force (USPSTF), while permitting immediate colonoscopy as an option, did not categorize it as preferred. The ACG and MSTF also included CT colonography every five years, and fecal DNA testing as considerations. All three recommendation panels recommended replacing any older low-sensitivity, guaiac-based fecal occult blood testing (gFOBT) with either newer high-sensitivity guaiac-based fecal occult blood testing (hs gFOBT) or fecal immunochemical testing (FIT). MSTF looked at six studies that compared high sensitivity gFOBT (Hemoccult SENSA) to FIT, and concluded that there was no clear difference in overall performance between these methods.

The American College of Gastroenterology has recommended the abandoning of gFOBT testing as a colorectal cancer screening tool, in favor of the fecal immunochemical test. Though the FIT test is preferred, even the guaiac FOB testing of average risk populations may have been sufficient to reduce the mortality associated with colon cancer by about 25%. With this lower efficacy, it was not always cost effective to screen a large population with gFOBT.

If colon cancer is suspected in an individual (such as in someone with an unexplained anemia) fecal occult blood tests may not be clinically helpful. If a doctor suspects colon cancer, more rigorous investigation is necessary, whether or not the test is positive.

In 2006, the Australian Government introduced the National Bowel Cancer Program which has been updated several times since; targeted screening will be done of all Australians aged over 50 to 74 by 2017–2018. Cancer Council Australia recommended that FOBT should be done every two years. Gradually government fund disbursement meant that some people are not yet eligible for the national program and should pay for a FOBT by themselves.

The Canadian Cancer Society recommends that men and women age 50 and over have a FOBT at least every 2 years.

In colon cancer screening, using only one sample of feces collected by a doctor performing a digital rectal examination is discouraged.

The use of the M2-PK Test is encouraged over gFOBT for routine screening as it may pick up tumors that are both bleeding and non bleeding. It is able to pick up 80 percent of colorectal cancer and 44 percent for adenoma > 1 centimeter, while gFOBT picks up 13 to 50 percent of colorectal cancers.

Fundic gland polyps are found in 0.8 to 1.9% of patients who undergo esophagogastroduodenoscopy, and are more common in middle aged women.

The most important consideration in evaluating patients with FGPs is distinguishing between sporadic form (patients without any other gastrointestinal condition, usually in middle age with female prevalence) and syndromic form. This is to ascertain the risk of development of gastric cancer, and to ascertain the risk of concomitant colon cancer.

FGPs can be found in association with the following genetic conditions:

- familial adenomatous polyposis

- attenuated familial adenomatous polyposis syndromes

- Zollinger-Ellison syndrome

- gastric adenocarcinoma associated with proxymal polyposis of the stomach (GAPPS): this condition, described in three families is characterized by development of antral adenomas and FGPs, with early development of severe dysplasia and gastric cancer, in absence of overt intestinal polyposis. This condition has been recently characterized by a point mutation in exon 1B of APC gene.

Sporadic FGPs have been associated with:

- chronic use of proton pump inhibitors (proposed by some authors, denied by others)

- "Helicobacter pylori" infection: there is a reverse relationship between infection and fundic gland polyps, and infection by "H pylori" causes polyps regression.

Immunohistochemistry is now being used more often to diagnose patients likely to have Muir–Torre syndrome. Sebaceous neoplasms are only infrequently encountered, and immunohistochemistry is reliable and readily available, so researchers have recommended its use. Routine immunohistochemical detection of DNA mismatch repair proteins help identify hereditary DNA mismatch repair deficiency.

Treatment of Muir–Torre syndrome normally consists of oral isotretinoin. The drug has been found to prevent tumor development.

Patients with Muir–Torre syndrome should follow the same stringent screening for colorectal carcinoma and other malignancies as patients with Lynch syndrome. This includes frequent and early colonoscopies, mammograms, dermatologic evaluation, and imaging of the abdomen and pelvis.

Treatment:wide excision taking 8mm normal tissue as this is locally malignant. For recurrence radiotherapy is given

99% of cervical polyps will remain benign and 1% will at some point show neoplastic change. Cervical polyps are unlikely to regrow.

Muir–Torre was observed to occur in 14 of 50 families (28%) and in 14 of 152 individuals (9.2%) with Lynch syndrome, also known as HNPCC.

The 2 major MMR proteins involved are hMLH1 and hMSH2. Approximately 70% of tumors associated with the MTS have microsatellite instability. While germline disruption of hMLH1 and hMSH2 is evenly distributed in HNPCC, disruption of hMSH2 is seen in greater than 90% of MTS patients.

Gastrointestinal and genitourinary cancers are the most common internal malignancies. Colorectal cancer is the most common visceral neoplasm in Muir–Torre syndrome patients.

The most common method of testing for hepatoblastoma is a blood test checking the alpha-fetoprotein level. Alpha-fetoprotein (AFP) is used as a biomarker to help determine the presence of liver cancer in children. At birth, infants have relatively high levels of AFP, which fall to normal adult levels by the first year of life. The normal level for AFP in children has been reported as lower than 50 nanograms per milliliter (ng/ml) and 10 ng/ml. An AFP level greater than 500 (ng/ml) is a significant indicator of hepatoblastoma. AFP is also used as an indicator of treatment success. If treatments are successful in removing the cancer, the AFP level is expected to return to normal.

Cervical polyps can be removed using ring forceps. They can also be removed by tying surgical string around the polyp and cutting it off. The remaining base of the polyp can then be removed using a laser or by cauterisation. If the polyp is infected, an antibiotic may be prescribed.