What is Familial Adenomatous Polyposis?
Familial adenomatous polyposis (FAP) is a type of syndrome where a family member passes down a trait that causes the growth of numerous polyps, or noncancerous growths, in the colon and rectum. This is caused by an inherited mutation, or a change in the genetic make-up, in a specific gene known as the adenomatous polyposis coli (APC). FAP can appear in a variety of ways, including conditions known as Gardner and Turcot syndromes.
If FAP is not treated, the affected person could develop hundreds or even thousands of these polyps in their colon and rectum. This usually begins in their early teen years. Unfortunately, this condition virtually guarantees a person will get colorectal cancer, a type of cancer that starts in the colon or rectum, usually before the age of 40. The removal of the colon, a procedure known as a colectomy, is advised to significantly lower the risk of developing this type of cancer. People with FAP also have a higher chance of developing other types of cancers, such as those affecting the stomach and the first part of the small intestine, the liver’s precursor cells, and tumors that form in the body’s connective tissue. This is why it is very important to regularly screen for cancers in the upper digestive system and other parts of the body in people affected by this disorder.
What Causes Familial Adenomatous Polyposis?
FAP, or Familial Adenomatous Polyposis, is a health condition that occurs due to changes or mutations in a specific gene, the APC gene. This gene, which plays an essential role in preventing tumors or growths, is found on chromosome 5 and passes down through families, which means that if one of your parents has this mutated gene, there’s a chance you could inherit it. Shadowed variations of the APC gene can lead to different types of FAP, and where exactly this mutation occurs on the gene can influence how the disease shows itself, including various extra symptoms related to areas outside the colon.
Sometimes, the APC gene mutation can lead to a less severe form of FAP, known as Attenuated FAP. This variation usually creates fewer polyps, appears later in life, and slowly progresses towards cancer. There are other variations of FAP, like Gardner syndrome, which is characterized by growths or polyps in the colon, bone tumors, and cancers in the soft tissues. Then there’s Turcot syndrome, which involves polyps in the colon and tumors in the central nervous system (the brain and spinal cord).
These variations often include additional symptoms outside the colon.
If you have more than 20 adenomatous polyps (abnormal tissue growth) found during a colonoscopy or cancers consistent with FAP, it’s recommended that you undergo genetic testing. It’s important to note that while around 10% to 30% of people diagnosed with FAP don’t show any detectable gene mutation, family members are still recommended to monitor as though there is a detectable mutation. This is because of the hereditary nature of the disease and the chance that the gene mutation may not be immediately noticeable.
Risk Factors and Frequency for Familial Adenomatous Polyposis
FAP, or Familial Adenomatous Polyposis is the second most common genetically inherited disorder, leading to multiple polyps. The rate of occurrence varies, and it’s estimated to happen in about 1 in every 5000 to 18,000 people. It’s important to note that it affects both males and females equally and is responsible for about 1% of colorectal cancer cases.
- The rate of occurrence for FAP is about 1 in every 5000 to 18,000 people.
- FAP affects both men and women equally.
- It’s responsible for about 1% of colorectal cancer cases.
- About 20% to 30% of people diagnosed with FAP show new APC mutations and don’t have a documented family history of the disease.
- The rates of incidence for attenuated FAP and other FAP variants are currently unknown.
Signs and Symptoms of Familial Adenomatous Polyposis
Familial Adenomatous Polyposis (FAP), a condition characterized by the growth of numerous polyps in the colon, can manifest differently based on one’s family history. Symptoms can be seen in the colon and areas outside the colon. Patients may not be aware they have the condition until they are diagnosed with young-onset colorectal cancer or during a screening colonoscopy.
Colon Symptoms
Most patients have vague symptoms, such as diarrhea, abdominal pain, and rectal bleeding. Diagnosis often occurs during a screening colonoscopy where many polyps, sometimes over 100, are discovered throughout the colon. A milder form of FAP, called “Attenuated FAP,” involves fewer polyps, usually around 30, and presents later in life, typically after 50 years of age. The severity of symptoms and signs can depend on the extent of polyposis and the stage of any colon cancer.
Non-Colon Symptoms
FAP may also affect other parts of the body. Specific to FAP, the retinas can thicken and result in localized, pigmented retinal lesions usually without symptoms. An eye exam may reveal these changes. FAP may also cause dental abnormalities, such as supernumerary or impacted teeth, odontomas, and cysts. Lastly, bone growths known as osteomas can occur in areas like the jaw or skull.
- Colon-associated symptoms: Diarrhea, abdominal pain, rectal bleeding
- Colon polyps found during colonoscopy
- Retinal changes noted during an eye exam
- Dental abnormalities
- Osteomas in jaw or skull
Another manifestation of FAP is the development of desmoid tumors. These benign growths are often large and do not spread to other areas but can grow aggressively and invade local structures. They occur in about 10-15% of FAP patients, most commonly in the abdomen. If there is a family history of these tumors, the risk shoots up to 25%. The likelihood of developing these tumors is about twice as high in women than men and can be related to surgical trauma. Therefore, surgery for FAP is often delayed in young patients. Monitoring these tumors typically involves annual abdominal exams or imaging studies. If necessary, these tumors can be treated with medication or removed surgically.
The majority of FAP patients, 90%, show gastric polyps, which usually do not become cancerous. Non-fundic gland polyps, however, are more frequently cancerous and require endoscopic management. High-grade dysplasia in any gastric polyp necessitates endoscopic or surgical resection based on guidelines.
Periampullary and duodenal cancers are the leading causes of death in FAP patients after colon cancer. The lifetime risk of duodenal cancer is about 5% by age 60. Guidelines recommend starting surveillance at age 20 to 25 and repeating it every 2 to 3 years. Management depends on the polyp’s pathology and location.
Other cancers seen in FAP include hepatoblastoma, which affects male children under 5 years of age. Screening protocols are not well-established but typically include a liver ultrasound and checks of alpha-fetoprotein levels every 3 to 6 months for high-risk children.
Lastly, about 2% of FAP patients develop thyroid cancer, primarily the papillary type. Women with FAP are much more likely to have thyroid cancer than their male counterparts. Therefore, starting in the teenage years, regular thyroid checks are recommended.
Testing for Familial Adenomatous Polyposis
According to the guidelines from the National Cancer Comprehensive Network, if you test positive for a mutation in a gene known as APC, you should go for a specific type of examination called a sigmoidoscopy or colonoscopy every year. This testing usually begins when you’re between 10 to 15 years old.
This gene mutation is connected to a condition called Familial Adenomatous Polyposis (FAP), which can lead to other health issues besides colon problems. Therefore, it’s important that other parts of your body are checked regularly too.
For example, when you’re around 20 to 25 years old, it’s recommended that you get an ‘upper endoscopy’. This is a procedure where a thin tube with a camera is used to check your stomach and the first part of your small intestine. If you have to have an operation to remove your colon before this age, this endoscopy will also be needed earlier. The aim of this test is to thoroughly examine a small area called the ampulla of Vater, which is where your bile and pancreatic ducts open into your small intestine.
Additionally, every year you should have your abdomen manually checked for hard lumps or tumors. If you’ve previously had your colon removed and desmoid tumors (benign growths) run in your family, you may also need regular imaging tests such as a CT scan or an MRI. These scans use powerful technology to create detailed images of the inside of your body.
Starting in your late teens, it’s also advised that you have regular checks for thyroid cancer. This involves physical examinations and ultrasound scans of your thyroid, a small gland in your neck that regulates your body’s energy and metabolism.
Currently, there’s not enough evidence to recommend routine checks for brain tumors, a rare form of liver cancer known as hepatoblastoma, and cancer of the pancreas but ongoing research may change this in the future.
Treatment Options for Familial Adenomatous Polyposis
Patients who have Familial Adenomatous Polyposis (FAP), a condition where numerous polyps form mainly in the epithelium of the large intestine, might require different treatments based on how severe their disease is, how it’s showing up in their body, and other personal factors like their age, overall health, and personal circumstances.
For the disease as it affects the large intestine (colonic disease), the most definite treatment is to remove parts of the colon and rectum that are at risk of forming polyps. Various surgical operations can do this. The first type of surgery removes the entire colon and rectum, a procedure called total proctocolectomy with ileal pouch-anal anastomosis or end ileostomy. This surgery is especially useful for getting rid of tissues that could develop more polyps. But, after this surgery, patients will need to live with an ileostomy, a procedure that allows waste to exit the body from an opening in the abdominal wall, which could be challenging for younger patients. Alternatively, there’s a procedure called restorative proctocolectomy where surgeons construct a sort of internal pouch to store and pass waste. However, this might affect a person’s quality of life, leading to changes in bowel control and sexual and reproductive function.
The second type of surgery, total abdominal colectomy with an ileorectal anastomosis, is less extensive and leaves the rectum intact. Though it can improve control over bowel movements and sexual function, this procedure may increase the chance of cancer forming in the rectal tissue left behind, and therefore, the patient requires regular check-ups. About one-third of these patients will eventually develop rectal cancer and need further surgery.
Choosing the right surgery depends on how severely the disease has affected the patient, their family history of the disease, and what the patient prefers. Total proctocolectomy is recommended for patients with a lot of rectal polyps, while those with fewer polyps might choose total abdominal colectomy. Lifestyle considerations like bowel control and sexual function can significantly influence the decision, especially for younger patients.
Patients with a milder version of FAP might need less invasive surgical procedures. For these patients, it’s crucial to keep a close eye on the areas where the surgery happened. For example, people who had total proctocolectomy should have an annual endoscopy, a procedure that allows physicians to inspect the digestive tract, while people with a rectum left in place should have an endoscopy every 3 to 6 months.
There’s ongoing research into treatments outside of surgery that might help delay when the patient needs to have part of their colon removed. For example, Sulindac, an anti-inflammatory drug, has shown promise by reducing the amount and size of polyps in some studies.
FAP affects areas outside the large intestine (extracolonic disease), too. Polyps developing in the digestive tract can cause significant harm and could be fatal — this is particularly the case for patients who have already had part of their colon removed. People with FAP should, therefore, regularly have an endoscopy to spot polyps in the stomach or small intestine early. Doctors keep an eye on most stomach polyps without intervening, as they are usually safe, but larger ones might need to be removed. Small intestinal polyps need close monitoring, and larger ones must be removed. They might resort to further treatments if there’s extensive disease or cancer.
Patients with FAP, especially those with a family history of desmoid tumors (benign growths that can develop anywhere in the body), are significantly more likely to develop this condition. For these patients, regular examinations are critical. Since surgery can increase the risk of desmoid tumors, it’s recommended to postpone surgical treatment as long as possible. Desmoid tumors in the mesentery (the tissues that attach the intestines to the abdominal wall) might need removal if they start to press against essential blood vessels. Before and after the surgery, a type of medication could assist in reducing the size of the tumor.
What else can Familial Adenomatous Polyposis be?
When a doctor is trying to diagnose Familial Adenomatous Polyposis (FAP), they also need to consider other conditions that have similar symptoms. These might include:
- Hereditary nonpolyposis colon syndrome
- MUTYH-associated polyposis
- Hyperplastic polyposis
- Inflammatory polyposis
- Juvenile polyposis syndrome
- Lymphomatous polyposis
- Neurofibromatosis type 1
What to expect with Familial Adenomatous Polyposis
If Familial Adenomatous Polyposis (FAP) is not treated, it can almost always progress to colorectal cancer, which is a serious type of cancer affecting the large intestine. This can result in shorter lifespans, with the majority of patients not living past their 40s. However, with proper screening and preventive measures, the survival rates can be significantly improved. One of these preventive measures might be a colectomy, a surgery to remove part or all of your colon.
It’s important to continue checking for other types of cancer, too. For example, duodenal cancer, a cancer of the small intestine, can become a highly serious issue for individuals who’ve had their colon inspected through colonoscopy. Because a disease such as FAP can be diagnosed early, the news can take a heavy emotional toll on patients. As such, providing emotional and psychological support is crucial.
Managing this condition isn’t something that should be done alone. It’s very important to have a team of different types of healthcare providers to give the best possible care and guidance.
Possible Complications When Diagnosed with Familial Adenomatous Polyposis
Some complications linked with known FAP conditions are:
- All patients (100%) develop colon and rectum cancer
- About 10% of patients develop cancers involving the beginning of the small intestine or the ampulla of Vater (a small opening that drains pancreatic and bile ducts into the small intestine)
- Up to 20% of patients develop benign but potentially life-threatening tumours called desmoid tumours
- Some patients might also develop additional cancer types like liver, brain, and thyroid cancers
Preventing Familial Adenomatous Polyposis
FAP, or Familial Adenomatous Polyposis, is a condition passed down through families that causes growths, known as polyps, to form in the colon. These polyps raise the risk of developing colon cancer and can also show up in other parts of the body. It’s especially important for people with a family history of early colon cancer or colon polyps to get diagnosed early with regular check-ups.
Medications can help manage the condition, but the main treatment often involves removing part of or the entire colon, sometimes including the rectum (the end part of the colon). People with FAP may also develop problems outside the colon, so thorough screenings and frequent doctor’s visits are required.
With these regular check-ups and potential surgery, people who have FAP can greatly lower their chances of getting colorectal cancer and other related cancers. It’s also highly recommended that all family members get tested to see if they have this genetic condition.
Living with FAP often requires life-long monitoring and a strong support network that includes emotional and social support, to ensure the best possible health outcomes.
