Treatment for FAP depends on the genotype. Most individuals with the APC mutation will develop colon cancer by the age of 40, although the less-common attenuated version typically manifests later in life (40–70). Accordingly, in many cases, prophylactic surgery may be recommended before the age of 25, or upon detection if actively monitored. There are several surgical options that involve the removal of either the colon or both the colon and rectum.

- Rectum involved: the rectum and part or all of the colon are removed. The patient may require an ileostomy (permanent stoma where stool goes into a bag on the abdomen) or have an ileo-anal pouch reconstruction. The decision to remove the rectum depends on the number of polyps in the rectum as well as the family history. If the rectum has few polyps, the colon is partly or fully removed and the small bowel (ileum) can be directly connected to the rectum instead (ileorectal anastomosis).

- Rectum not involved: the portion of the colon manifesting polyps can be removed and the ends 'rejoined' (partial colectomy), a surgery that has a substantial healing time, but leaves quality of life largely intact.

Prophylactic colectomy is indicated if more than a hundred polyps are present, if there are severely dysplastic polyps, or if multiple polyps larger than 1 cm are present.

Treatment for the two milder forms of FAP may be substantially different from the more usual variant, as the number of polyps are far fewer, allowing more options.

Various medications are being investigated for slowing malignant degeneration of polyps, most prominently the non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDS have been shown to significantly decrease the number of polyps but do not usually alter management since there are still too many polyps to be followed and treated endoscopically.

Polyps can be removed during a colonoscopy or sigmoidoscopy using a wire loop that cuts the stalk of the polyp and cauterises it to prevent bleeding. Many "defiant" polyps—large, flat, and otherwise laterally spreading adenomas—may be removed endoscopically by a technique called endoscopic mucosal resection (EMR), which involves injection of fluid underneath the lesion to lift it and thus facilitate surgical excision. These techniques may be employed as an alternative to the more invasive colectomy.

Prior to reaching the advanced stages of colorectal cancer, the polyps are confined to the inner wall and thickness of the intestinal tract and do not metastasize or 'spread'. So provided FAP is detected and controlled either at the pre-cancerous stage or when any cancerous polyps are still internal to the intestinal tract, surgery has a very high success rate of preventing or removing cancer, without recurrence, since the locations giving rise to cancer are physically removed "in toto" by the surgery.

Following surgery, if a partial colectomy has been performed, colonoscopic surveillance of the remaining colon is necessary as the individual still has a risk of developing colon cancer. However, if this happened, it would be a fresh incident from polyps developing anew in the unremoved part of the colon subsequent to surgery, rather than a return or metastasis of any cancer removed by the original surgery.

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.

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

Surgery remains the front-line therapy for HNPCC. There is an ongoing controversy over the benefit of 5-fluorouracil-based adjuvant therapies for HNPCC-related colorectal tumours, particularly those in stages I and II.

Polyps are either pedunculated (attached to the intestinal wall by a stalk) or sessile (grow directly from the wall).

PLGAs are treated with wide local surgical excision and long-term follow-up.

There is a recurrence rate of 14% (Peterson, contemporary of oral and maxillofacial surgery).

Some benign tumors need no treatment; others may be removed if they cause problems such as seizures, discomfort or cosmetic concerns. Surgery is usually the most effective approach and is used to treat most benign tumors. In some case other treatments may be of use. Adenomas of the rectum may be treated with sclerotherapy, a treatment in which chemicals are used to shrink blood vessels in order to cut off the blood supply. Most benign tumors do not respond to chemotherapy or radiation therapy, although there are exceptions; benign intercranial tumors are sometimes treated with radiation therapy and chemotherapy under certain circumstances. Radiation can also be used to treat hemangiomas in the rectum. Benign skin tumors are usually surgically resected but other treatments such as cryotherapy, curettage, electrodesiccation, laser therapy, dermabrasion, chemical peels and topical medication are used.

Wide, radical, complete surgical excision is the treatment of choice, with free surgical margins to achieve the best outcome and lowest chance of recurrence. Radiation is only used for palliation. In general, there is a good prognosis, although approximately 50% of patients die from disease within 3–10 years of presentation.

Treatment is mainly surgical; radiotherapy or chemotherapy is usually an indication of relapse. Head and neck desmoid fibromatosis is a serious condition due to local aggression, specific anatomical patterns and the high rate of relapse. For children surgery is particularly difficult, given the potential for growth disorders.

Treatment includes prompt radical excision with a wide margin and/or radiation. Despite their local infiltrative and aggressive behavior, mortality is minimal to nonexistent for peripheral tumours. In intra-abdominal fibromatosis associated with Familial adenomatous polyposis (FAP), surgery is avoided if possible due to high rates of recurrence within the abdomen carrying significant morbidity and mortality. Conversely, for intra-abdominal fibromatosis without evidence of FAP extensive surgery may still be required for local symptoms, but the risk of recurrence is low.

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.

Surgery is the mainstay of treatment for clinically localized disease. In feasible cases, a partial cystectomy with "en-bloc" resection of the median umbilical ligament and umbilicus can achieve good results. In progressed stages, radiotherapy seems not to lead to sufficient response rates. However, chemotherapy regimes containing 5-FU (and Cisplatin) have been described to be useful in these cases. In recent years, targeted therapies have been demonstrated to be useful in reports of single cases. These agents included Sunitinib, Gefitinib, Bevacizumab and Cetuximab.

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.

The treatment is dependent on the stage. As the prognosis of this tumour is usually good, fertility sparing approaches (conization, cervicectomy) may be viable treatment options.

Surgical removal of the tumor, adjuvant chemotherapy prior to tumor removal, and liver transplantation have been used to treat these cancers. Primary liver transplantation provides high, long term, disease-free survival rate in the range of 80%, in cases of complete tumor removal and adjuvant chemotherapy survival rates approach 100%. The presence of metastases is the strongest predictor of a poor prognosis.

Treatment is variable, both due to its rarity and to its frequently slow-growing nature. Treatment ranges from watchful waiting to debulking and hyperthermic intraperitoneal chemotherapy (HIPEC, also called intraperitoneal hyperthermic chemotherapy, IPHC) with cytoreductive surgery.

The standard of care for mucinous adenocarcinoma with clinical condition PMP involves cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC), by surgical oncologists who specialize in treating PMP. Some surgeons also apply early post-operative intraperitonial chemotherapy (EPIC), adjunct to surgical cytoreduction and HIPEC. In situations where surgery is not required immediately, patients can be monitored via CT scans, tumor marker laboratory tests, and physical symptoms, to determine when, and if, surgery is warranted. Although some surgical procedures may be rather extensive, patients can and do recover from surgery, and the majority of these patients can and do live productive lives.

In debulking, the surgeon attempts to remove as much tumor as possible. CRS or cytoreductive surgery involves surgical removal of the peritoneum and any adjacent organs which appear to have tumor seeding. Since the mucus tends to pool at the bottom of the abdominal cavity, it is common to remove the ovaries, fallopian tubes, uterus, and parts of the large intestine. Depending upon the spread of the tumor, other organs might be removed, including but not limited to the gallbladder, spleen, and portions of the small intestine and/or stomach. For organs that cannot be removed safely (like the liver), the surgeon strips off the tumor from the surface.

The first line of treatment for nasal polyps is topical steroids. Steroids decrease the inflammation of the sinus mucosa to decrease the size of the polyps and improve symptoms. Topical preparations are preferred in the form of a nasal spray, but are often ineffective for people with many polyps. Steroids by mouth often provide drastic symptom relief, but should not be taken for long periods of time due to their side effects. Because steroids only shrink the size and swelling of the polyp, people often have recurrence of symptoms once the steroids are stopped. Decongestants do not shrink the polyps, but can decrease swelling and provide some relief. Antibiotics are only recommended if the person has a co-occurring bacterial infection.

In people with nasal polyps caused by aspirin or NSAIDs, avoidance of these medications will help with symptoms. Aspirin desensitization has also been shown to be beneficial.

Polyps on the vocal folds can take on many different forms, and can sometimes result from vocal abuse, although this is not always the cause. They can occur on one or both vocal folds, and appear as swelling, a bump (similar to a nodule), a stalk-like growth, or a blister-like lesion. Most polyps are larger than nodules, which are more similar to callouses on the vocal folds.

Polyps and nodules can exhibit similar symptoms including hoarseness or breathiness, “rough” or “scratchy” voice, harshness in vocal quality, shooting pain from ear to ear, sensation of having “a lump in the back of the throat”, neck pain, decreased pitch range in the voice, and vocal and bodily fatigue.

If an individual experiences symptoms for more than 2 to 3 weeks, they should see a physician. For a diagnosis, a thorough evaluation of the voice should include a physical examination, preferably by an otolaryngologist (ear, nose, and throat doctor) who specializes in voice, a voice evaluation with a speech-language pathologist (SLP), a neurological examination (in certain cases)

The qualities of the voice that will be evaluated include quality, pitch, loudness, and ability to sustain voicing. In some cases, an instrumental examination may be performed with an endoscope into the mouth or nose; this gives a clear look at the vocal folds and larynx in general. In addition to this, a stroboscope (flashing light) may be used to observe the movement of the vocal folds during speech.

Polyps may be treated with medical, surgical, or behavioral intervention. Surgical intervention involves removing the polyp from the vocal fold. This approach is only used when the growth(s) are very large, or have existed for an extended amount of time. In children, surgical intervention is rare. Existing medical problems may be treated in an effort to reduce the strain and negative impact on the vocal cords. This could include treatment for gastrointestinal reflux disease, allergies, and thyroid problems. Intervention to stop smoking and reduce stress may also be needed. Most people receive behavioral intervention, or vocal therapy, from an SLP. This might involve teaching good vocal hygiene, and reducing or stopping vocal abuse behaviors. Direct voice treatments may be used to alter pitch, loudness, or breathe support to promote good voicing.

Treatment may include the following:

- Surgery with or without radiation

- Radiotherapy

Fast neutron therapy has been used successfully to treat salivary gland tumors, and has shown to be significantly more effective than photons in studies treating unresectable salivary gland tumors.

- Chemotherapy

Polyps can be surgically removed using curettage with or without hysteroscopy. When curettage is performed without hysteroscopy, polyps may be missed. To reduce this risk, the uterus can be first explored using grasping forceps at the beginning of the curettage procedure. Hysteroscopy involves visualising the endometrium (inner lining of the uterus) and polyp with a camera inserted through the cervix. If it is a large polyp, it can be cut into sections before each section is removed. If cancerous cells are discovered, a hysterectomy (surgical removal of the uterus) may be performed. A hysterectomy would usually not be considered if cancer has been ruled out. Whichever method is used, polyps are usually treated under general anesthetic.

It is unclear if removing polyps affects fertility as it has not been studied.

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.

Wide excision is the treatment of choice, although attempting to preserve hearing. Based on the anatomic site, it is difficult to completely remove, and so while there is a good prognosis, recurrences or persistence may be seen. There is no metastatic potential. Patients who succumb to the disease, usually do so because of other tumors within the von Hippel-Lindau complex rather than from this tumor.

Chemotherapy has relatively poor curative efficacy in SRCC patients and overall survival rates are lower compared to patients with more typical cancer pathology. SRCC cancers are usually diagnosed during the late stages of the disease, so the tumors generally spread more aggressively than non-signet cancers, making treatment challenging. In the future, case studies indicate that bone marrow metastases will likely play a larger role in the diagnosis and management of signet ring cell gastric cancer.

In SRCC of the stomach, removal of the stomach cancer is the treatment of choice. There is no combination of chemotherapy which is clearly superior to others, but most active regimens include 5-Fluorouracil (5-FU), Cisplatin, and/or Etoposide. Some newer agents, including Taxol and Gemcitabine (Gemzar) are under investigation.

In a single case study of a patient with SRCC of the bladder with recurrent metastases, the patient exhibited a treatment response to palliative FOLFOX-6 chemotherapy.