- Hereditary Nonpolyposis Colorectal Cancer
- The Mechanism of HNPCC Being Passed From a Parent to a Child
- The Process of Diagnosing HNPCC
- The Procedure of Genetic Testing
- Recommendations for the Screening of HNPCC Patients
Hereditary Nonpolyposis Colorectal Cancer
Colorectal cancer is considered to be the third most often occurring cancer in the US. Every year, approximately 130,000 people face it. Besides, it’s exactly this type of cancer that (according to the US statistics on cancers) leads to lethal consequences. At the same time, in case the disease is detected in the very beginning, it turns out to be possible to get rid of in 90 % of cases.
As for the reason of colorectal cancer, it should be pointed out that there occur mutations in some genes of the colon cancer cells. These cells are responsible for keeping an eye on the growth and death of the cells in your organism. Approximately 5 % of all patients face HNPCC or hereditary non-polyposis colorectal cancer. The key point of it is defects in the genes that are, usually, passed from parents to a child.
The letter “H” in the name of the disease means “hereditary”. Consequently, you understand that the disease is, as a rule, inherited. The letters “NP” mean “non-polyposis”. This way we can differentiate the disease from the syndrome, a particular feature of which is the formation of polyps. The letters “CC” mean “colorectal cancer”. Actually, this is the cancer that very often develops in HNPCC families.
The Mechanism of HNPCC Being Passed From a Parent to a Child
The main reason for the occurrence of HNPCC is defects in the genes that normally repair our DNA. There exist at least 5 such like genes – mismatch repair genes. Abnormalities that take place in these genes may lead to HNPCC. If genetic damage is not repaired, you may face cancer. If your case of cancer is inherited, there will be defects present in all the cells of your organism. Consequently, other cancers, such as cancer of uterus, ovarian cancer, cancer that affects gastrointestinal tract, urinary tract and kidneys may easily develop.
Even though people who have HNPCC have an increased risk of developing cancer, you’re still highly recommended to get more information on the syndrome, undergo necessary screenings as well as receiving the necessary treatment. This way the cancer may be prevented and your life will be saved.
The Process of Diagnosing HNPCC
The key point that helps the experts to define whether your family is quite likely to face HNPCC is a detailed family history. There are several criteria on the basis of which your doctor may suspect that you are a subject to having HNPCC.
The most strict criteria involve:
- Having three relatives that deal with colorectal cancer.
- Having a relative that was diagnosed with the disease at or under the age of 50.
- Having a first-degree relative (parent, child, sibling) suffering from the disease.
- Keep in mind that colorectal cancer occurs in 2 successive generations.
Less strict criteria involve:
- If there are 2 cases of colorectal and 1 case of uterine cancer in your family. There may also be 2 relatives suffering from colorectal cancer and advanced precancerous polyps as well.
- Having a relative who was diagnosed either with colorectal or uterine cancer at or under the age of 50.
- Having a first-degree relative diagnosed with cancer to the other 2 who suffer from polyps.
- Pay attention to the fact that cancers occur in 2 successive generations.
- Being prone to having 2 associated with HNPCC cancers. The list of such like cancers includes: colorectal cancer, uterine or endometrial cancer, cancer of small bowl or ureter cancer and renal pelvis.
- Having one first-degree relative dealing with cancer to the other 2 with cancers as well.
- Don’t forget that cancers occur in 2 successive generations.
- There should be one relative whose cancer was detected under the age of 50.
Besides, there are other factors and conditions that are taken into account when diagnosing HNPCC in a family. They are having multiple relatives that have colorectal cancer, especially, if they were diagnosed with it at a young age, those people who have one more cancer apart from the colorectal one or clusters of colorectal cancer and other cancers that are associated with HNPCC.
The Procedure of Genetic Testing
If on the basis of the family history HNPCC has been suspected, you’re strongly recommended to receive genetic counselling before undergoing genetic testing. A genetic counselor will read through your family history through and discuss with you all the issues of the testing. Your emotional state is considered as well.
If in your case it’s quite likely that a case of an inherited colon cancer syndrome may occur, you’re to undergo blood testing. This way the gene mutations leading to HNPCC may be detected. Approximately 50 % of all HNPCC cases in families are stated to involve gene abnormalities. Besides, if any abnormalities have been detected in your family, other relatives are recommended to undergo the testing as well. The most important thing is that a gene testing being positive means only that in your case the gene mutation is inherited. In other words, the testing doesn’t say anything concerning polyps or cancer.
MSI or microsatellite instability is one more way of testing that is carried out on either cancerous tissue or polyps. If you have a positive MSI test accompanied by a strong family history, it’s quite likely that you have HNPCC. Still, genetic testing is to be followed by direct DNA.
Some patients, who have a positive DNA test, are recommended colorectal or gynecologic surveillance. This way the cancer may either be prevented or detected in the very beginning when it can be cured. If your family’s choice is not to undergo any genetic testing or it’s impossible to detect any gene abnormalities, there is still a need for surveillance on a regular basis.
The ways to prevent cancer in HNPCC family
- If you want to prevent the occurrence of colorectal cancer, you need to undergo colonoscopy on a regular basis. Most often, the reason for cancer development is adenomatous polyps that are possible to remove during the colonoscopy procedure.
- Moreover, undergoing screening on a regular basis in combination with a healthy diet and lifestyle may contribute greatly to the prevention of colorectal cancer. However, you definitely need to talk it over with your doctor before changing your lifestyle in any way.
- In case there has been detected cancer, the removal of the entire colon is recommended since it’s the only 100 % successful way to prevent the case of the disease recurrence. After the surgical operation, the majority of the patients is able to lead their usual lives and eat normal diets.
You can find information on HNPCC families in a registry. For example, David G. Jagelman Inherited Colorectal Cancer Registries at Cleveland Clinic. The main aim here is to prevent death from colon cancer. Therefore, you’re provided with the best care and you’re to know about absolutely all risks and studies.
Recommendations for the Screening of HNPCC Patients
Age: 21 or ten years younger than the youngest patient in your family that fights against colorectal cancer.
Interval: Until the age of 40, it is to be undergone every 2 years. After that, you’re to undergo it every year.
Method: Pelvic exam, transvaginal ultrasound and blood test for ovarian cancer known as CA-125.
Age: 25-35 years.
Interval: You’re to undergo it every year.
Method: Endometrial biopsy.
Age: Right after you start having such symptoms like persistent or unusual vaginal bleeding.
Method: Urine cytology.
This procedure is of paramount importance for those families who face either transitional cell carcinoma of the ureter or renal pelvis.
Age: Starting from 30 years.
Interval: You are to undergo it at least once a year or once in 2 years.
If it’s about other cancers that run in a family, there is a strong need for more specialized testing apart from the given basic recommendations.