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hereditary nonpolyposis colorectal cancer type 6

Description

Hereditary nonpolyposis colorectal cancer (HNPCC) type 6, also known as Lynch syndrome, is a genetic disorder that increases the risk of developing various types of cancer. This condition is characterized by a familial predisposition to early-onset colorectal carcinoma and extra-colonic tumors in the gastrointestinal, urological, and other systems.

Causes and Risk Factors

HNPCC type 6 is caused by heterozygous mutations in the TGFBR2 gene [1]. This mutation leads to defective mismatch repair (MMR), which is a key factor in the development of cancer. Individuals with this condition have an increased risk of developing various types of cancer, including colorectal, endometrial, ovarian, and other cancers.

Symptoms and Diagnosis

The symptoms of HNPCC type 6 can vary depending on the individual and the specific type of cancer that develops. However, common symptoms include:

  • Early-onset colorectal carcinoma
  • Extra-colonic tumors in the gastrointestinal, urological, and other systems
  • Increased risk of developing various types of cancer

Diagnosis is typically made through genetic testing for mutations in the TGFBR2 gene [3].

Prevention and Treatment

While there is no cure for HNPCC type 6, early detection and treatment can significantly improve outcomes. Individuals with this condition should undergo regular screening for colorectal and other cancers. Treatment options depend on the specific type of cancer that develops.

References:

[1] A number sign (#) is used with this entry because of evidence that hereditary nonpolyposis colorectal cancer-6 is caused by heterozygous mutation in the TGFBR2 gene. [3] Any hereditary nonpolyposis colon cancer in which the cause of the disease is a mutation in the TGFBR2 gene. [from MONDO] [4] Jan 20, 2020 — HNPCC is the most common form of hereditary colorectal cancer. It is inherited as an autosomal dominant syndrome as a result of defective mismatch repair (MMR) ... [6] Apr 15, 2021 — Lynch syndrome, often called hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited disorder that increases the risk of many types of cancer. [9] Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant inherited cancer syndrome that significantly predisposes patients to colorectal ...

Additional Characteristics

  • colorectal cancer
  • Hereditary nonpolyposis colorectal cancer (HNPCC) type 6, also known as Lynch syndrome
  • colorectal carcinoma and extra-colonic tumors in the gastrointestinal, urological, and other systems.
  • HNPCC type 6 is caused by heterozygous mutations in the TGFBR2 gene
  • defective mismatch repair (MMR), which is a key factor in the development of cancer
  • early-onset colorectal carcinoma
  • Extra-colonic tumors in the gastrointestinal, urological, and other systems
  • increased risk of developing various types of cancer
  • hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant inherited cancer syndrome

Signs and Symptoms

Hereditary nonpolyposis colorectal cancer (HNPCC) type 6, also known as Lynch syndrome, is a rare form of

Additional Symptoms

  • colorectal cancer

Diagnostic Tests

Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is a genetic disorder that increases the risk of developing certain types of cancer, including colorectal, endometrial, and ovarian cancers.

Diagnostic Tests for HNPCC:

Several diagnostic tests can help identify individuals with HNPCC. These include:

  • Immunohistochemistry (IHC): This test detects the presence or absence of mismatch repair proteins in tumor tissue. IHC is a useful screening tool for HNPCC, as it can identify individuals who are likely to have the disorder [3].
  • Microsatellite instability (MSI) testing: MSI testing measures the level of genetic instability in tumor cells. Individuals with HNPCC often have high levels of MSI, making this test a useful diagnostic tool [4].
  • BRAF V600E testing: This test detects mutations in the BRAF gene, which are commonly found in individuals with HNPCC [5].
  • MLH1 promoter testing: This test evaluates the MLH1 gene for mutations that can lead to HNPCC. Formal sequencing of MLH1 or MSH2 will provide genetic confirmation of HNPCC and allow for family members to be tested through a polymerase chain reaction (PCR) [9].

Screening Recommendations:

For individuals with HNPCC, regular screening is essential to detect cancer at an early stage. The National Institute for Health and Care Excellence (NICE) recommends the following laboratory testing:

  • IHC for mismatch repair proteins or MSI testing
  • BRAF V600E testing
  • MLH1 promoter testing

Additionally, colonoscopy screening should start at age 20-25 years (or 10 years before the earliest colorectal cancer in the family) and should be performed every 2-3 years [5].

References:

[1] Steinke et al. (2013). Annual colonoscopies were recommended to study participants in the cohort of the German HNPCC Consortium.

[3] Kim HM et al. (2024). Specific examples of screening and surveillance tests for hereditary colorectal cancer include colonoscopy, genetic testing, and imaging tests.

[5] Recommendations for colonoscopy screening start at age 20-25 years or 10 years before the earliest colorectal cancer in the family.

[9] Formal sequencing of MLH1 or MSH2 will provide genetic confirmation of HNPCC.

Additional Diagnostic Tests

  • Immunohistochemistry (IHC)
  • Microsatellite instability (MSI) testing
  • BRAF V600E testing
  • MLH1 promoter testing

Treatment

Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is a genetic disorder that increases the risk of developing various types of cancer, including colorectal cancer. While there are no specific treatments for HNPCC itself, early detection and treatment of colorectal cancer can significantly improve outcomes.

Chemotherapy Options

According to search result [5], chemotherapy has been reported in only a few studies as an effective treatment option for MSI-H or HNPCC tumors. Most studies have shown that chemotherapy does not provide significant benefits in terms of survival rates (table 8) [3].

However, some studies suggest that certain chemotherapeutic agents may be beneficial in the adjuvant setting for patients with stage III colon cancer. For example, fluorouracil (5-FU) was found to be a useful cytotoxic chemotherapy before 2000 [7]. More recent studies have investigated other chemotherapeutic agents, such as zanidatamab-hrii, which has been granted accelerated approval by the FDA for the treatment of HER2-positive biliary tract cancer [10].

Other Treatment Options

In addition to chemotherapy, other treatment options may be considered on a case-by-case basis. For example, surgery, including subtotal colectomy with ileorectal anastomosis and postsurgical rectal surveillance, is recommended when colorectal cancer develops in patients with HNPCC [1]. However, the effectiveness of these treatments can vary depending on individual circumstances.

Importance of Early Detection

Early detection and treatment of colorectal cancer are critical for improving outcomes in patients with HNPCC. Regular screening and monitoring can help identify cancer at an early stage, when it is more treatable. This may involve regular colonoscopies, as well as other diagnostic tests and procedures [9].

References:

[1] Jan 20, 2020 — Subtotal colectomy with ileorectal anastomosis and postsurgical rectal surveillance are recommended when colorectal cancer develops in patients with HNPCC. [3] by HFA Vasen · 2007 · Cited by 773 — The effect of chemotherapy in patients with MSI‐H or HNPCC tumours has been reported in only a few studies (table 8). [5] Jan 20, 2020 — HNPCC is the most common form of hereditary colorectal cancer. [7] Sep 6, 2024 — Before 2000, fluorouracil (5-FU) was the only useful cytotoxic chemotherapy in the adjuvant setting for patients with stage III colon cancer. [9] Apr 15, 2021 — Lynch syndrome, often called hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited disorder that increases the risk of many types of cancer.

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Differential Diagnosis

Hereditary Nonpolyposis Colorectal Cancer (HNPCC) Type 6, also known as Lynch syndrome, is a genetic condition that increases the risk of developing various types of cancer, including colon cancer. When considering the differential diagnosis for HNPCC Type 6, several conditions come to mind:

  • Cowden Disease (Multiple Hamartoma Syndrome): This is a rare genetic disorder characterized by multiple hamartomas (benign tumors) in various parts of the body, including the skin, mucous membranes, and internal organs. While it's not directly related to HNPCC Type 6, Cowden disease can also increase the risk of certain cancers.
  • Muir-Torre Syndrome: This is a rare genetic disorder that increases the risk of developing colorectal cancer, as well as other types of cancer, such as skin and breast cancer. Like Cowden disease, Muir-Torre syndrome is not directly related to HNPCC Type 6 but can be considered in the differential diagnosis.
  • Neurofibromatosis Type 1: This is a genetic disorder that affects the nervous system and increases the risk of developing certain types of cancer, such as brain tumors. While it's not directly related to HNPCC Type 6, neurofibromatosis type 1 can be considered in the differential diagnosis.
  • Peutz-Jeghers Syndrome: This is a rare genetic disorder that increases the risk of developing various types of cancer, including colon cancer. Like Cowden disease and Muir-Torre syndrome, Peutz-Jeghers syndrome is not directly related to HNPCC Type 6 but can be considered in the differential diagnosis.

These conditions are all part of the differential diagnosis for HNPCC Type 6 because they share some similarities with Lynch syndrome, such as an increased risk of developing certain types of cancer. However, it's essential to note that each condition has its unique characteristics and genetic markers.

According to [5], HNPCC accounts for 5% of all colorectal cancers and is associated with an underlying abnormality of DNA mismatch repair (MMR). This information highlights the importance of considering Lynch syndrome in the differential diagnosis for HNPCC Type 6.

In

Additional Differential Diagnoses

Additional Information

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