17097 Hereditary Non Polyposis Colorectal Cancer Hnpcc

Overview

Hereditary non-polyposis colorectal cancer (HNPCC), also called Lynch syndrome, is an inherited condition that greatly increases a person's chance of developing colorectal cancer and certain other cancers. It is caused by changes in specific genes that normally help repair mistakes made when cells divide. When these genes don't work properly, small errors in the DNA can build up and sometimes lead to cancer.

HNPCC is rare compared to other health conditions, but it is the most common type of inherited colorectal cancer. It is estimated to affect about 1 in 300 to 1 in 600 people, though many may not know they have it.

HNPCC affects both men and women equally. It runs in families, and a person can inherit the gene change from either parent. People with a family history of colorectal cancer or other HNPCC-related cancers, especially at a young age, are more likely to carry the gene change.

Symptoms

Common symptoms

• In the early stages, HNPCC often causes no symptoms at all.
• Changes in bowel habits, such as diarrhea or constipation lasting more than a few weeks
• Blood in the stool or black, tarry stools
• A feeling that the bowel does not empty completely
• Unexplained weight loss
• Fatigue or weakness
• Persistent abdominal pain or cramping

Causes

Main causes

• Changes (mutations) in genes that normally repair DNA, most commonly in genes called MLH1, MSH2, MSH6, and PMS2.
• These gene changes are usually inherited from a parent who carries the same change.
• Having HNPCC means the body's ability to fix cell mistakes is reduced, allowing errors to build up and sometimes trigger cancer.

Risk factors

• Having a parent, sibling, or child with a known HNPCC gene change
• A personal history of colorectal cancer or non-cancerous polyps at a young age (under 50)
• A family history of colorectal cancer or uterine cancer in multiple generations, especially at young ages
• A family history of other HNPCC-related cancers, such as ovarian, stomach, urinary tract, or small bowel cancer
• Being of certain ethnic backgrounds where a specific gene change is more common

When to see a doctor

See a doctor urgently if:

• If you notice blood in your stool or black, tarry stools
• If you have a sudden change in bowel habits lasting more than two weeks
• If you experience unexplained weight loss or severe fatigue
• If you have unusual abdominal pain or cramping that persists

Book a routine appointment if:

• If you have a family history of colorectal cancer or other HNPCC-related cancers, even without symptoms
• If you have had colorectal cancer or polyps at a young age
• If you are concerned about your genetic risk and would like a referral to a genetic counselor

Diagnosis

HNPCC is diagnosed through a combination of personal and family medical history, physical examination, and genetic testing. A doctor will ask about your family history of cancer, and may order tests to look for signs of cancer. If HNPCC is suspected, a genetic test on a blood or saliva sample can confirm the diagnosis.

Tests that may be done

• Colonoscopy to inspect the entire colon and rectum for polyps or cancer
• Genetic testing (blood or saliva) to look for changes in the known HNPCC genes
• Tissue testing of a previously removed polyp or tumor (if you have had one) to look for signs of DNA repair problems
• Possible imaging tests such as CT or MRI scans if cancer is suspected
• In women, evaluation of the uterus and ovaries may be offered due to increased risk

What to expect at your appointment

If you are having a colonoscopy, you will be asked to take a laxative preparation the day before to empty your bowels. You will likely receive a sedative to help you relax, and the test itself is usually not painful. Genetic testing involves a simple blood or saliva sample, and you will likely meet with a genetic counselor before and after the test to understand the results and what they mean for you and your family.

Treatment

Treatment for HNPCC focuses on preventing cancer and treating it early if it appears. Even if cancer is present, regular surveillance and timely treatment greatly improve the chances of a good outcome. The exact treatment plan depends on the type and stage of any cancer found, as well as your overall health.

Self-care at home

• Keep all recommended screening appointments, especially colonoscopy every 1 to 2 years starting at a young age.
• Report new symptoms to your healthcare provider without delay, even if they seem minor.
• Maintain a healthy weight and stay physically active to support overall health.
• Avoid tobacco and limit alcohol, as these can increase cancer risk.
• Talk openly with close family members about genetic testing so they can make informed choices.

Medical treatments

If a polyp or early cancer is found during a colonoscopy, it may be removed during that same procedure. For more advanced colorectal cancer, treatment may involve surgery to remove the affected part of the bowel, followed by chemotherapy if the cancer has spread. Other cancers associated with HNPCC are treated similarly to non-inherited cases, often with a combination of surgery, radiation, and medication. Your medical team will tailor treatment to your specific situation.

When is surgery considered?

In some cases, especially for people who have already had colorectal cancer or who have a very strong family history, a surgeon may recommend removing the colon (colectomy) to greatly reduce the risk of future colon cancer. For women with HNPCC, removing the uterus and ovaries may also be considered after childbearing years, as these organs have a higher risk of cancer. These decisions are personal and should be made with a specialist team after discussing all risks and benefits.

Living with this condition

Living with HNPCC means staying close to your healthcare team and following a personal screening plan. Many people find it helpful to keep a family health record and to attend appointments regularly. It is normal to have worries about cancer, but staying active and sticking to your schedule of tests can give you confidence and control.

Lifestyle tips

• Get regular physical activity — even walking can be helpful.
• Aim for a diet rich in fruits, vegetables, whole grains, and lean protein.
• Stay connected with friends, family, or a support group.
• Limit alcohol and avoid smoking.
• Try to get enough sleep and manage stress with relaxation or hobbies you enjoy.

Diet and exercise

No specific diet can guarantee protection against cancer, but a balanced diet with plenty of fiber, fresh vegetables, and whole grains may support digestive health. Regular exercise, such as 30 minutes of moderate activity most days, can help maintain a healthy weight and reduce overall cancer risk. Always drink plenty of water and check with your doctor if you have dietary restrictions.

Mental health and emotional wellbeing

Learning that you carry a high-risk gene can be stressful and may bring feelings of anxiety, fear, or worry. These feelings are natural and shared by many in the same situation. It is important to talk with your healthcare provider about mental health. If you are feeling overwhelmed, reach out to a counselor or psychologist who can help you develop coping strategies.

Prevention

HNPCC itself cannot be prevented because it is inherited, but you can take strong steps to prevent cancers from developing or progressing. The most important step is regular screening, especially colonoscopy, which can detect polyps early and remove them before they turn into cancer. Some people also choose preventive surgery after discussing risks with their medical team.

Screening programmes

If you have HNPCC, screening usually begins in your early twenties or at a doctor's recommendation. A typical plan includes a colonoscopy every 1 to 2 years, and women may have additional screening for endometrial and ovarian cancer, such as pelvic exams or ultrasound. Screening for other HNPCC-related cancers may also be suggested. Your doctor will help you create a plan based on your age and family history.

Complications

If left untreated

• Untreated HNPCC greatly increases the risk of developing colorectal cancer, often at a young age.
• Cancers in HNPCC may develop faster than in the general population, so a delay in screening can allow early growths to become invasive cancer.
• Other cancers, such as endometrial, ovarian, stomach, urinary tract, and small bowel cancer, can also occur without regular surveillance.
• Advanced cancers can spread to other organs, making treatment harder and reducing the chance of recovery.

Long-term outlook

With early detection and regular monitoring, the outlook for people with HNPCC is very hopeful. Colonoscopy and other screening tests catch polyps before they become cancer, and when cancer is found early, survival rates are high. Even if cancer develops, modern treatments are effective. Many people with HNPCC live long, healthy lives by staying on top of their screening and treatment plan.

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