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Inherited Cancers — what’s the risk? Part 2 in a 2-part series

  • 08.08.2017
hereditary cancer

 

In Part 1 of this series, we looked at five of the more common inherited cancers. These included: colorectal, breast, kidney, melanoma, and ovarian cancers. In this blog, we look at the 6th through 10th most common inherited cancers.

 

When trying to determine if cancer might run in a family, these factors must be assessed:

  • Who has the cancer? How are you related? Which side of the family are they on?
  • What type of cancer is it? Is it rare?
  • How old was this relative when they were diagnosed?
  • Did this person get more than one type of cancer?
  • Did they have any known risk factors for their type of cancer (such as smoking for lung cancer)?

 

When many cases of cancer occur in a family, it is often due to chance or because family members have been exposed to a common risk factor, such as smoking. However, in some cases cancer is caused by an abnormal gene that is passed along from generation to generation. With five to 10 percent of all cancers caused by inherited genes, it’s important to understand your risk if a close relative (parent or sibling) has cancer.

 

 

6. Prostate cancer

Prostate cancer is the most common cancer in men in the U.S. with 161,360 new cases estimated to be diagnosed in 2017. Family history is the strongest risk factor for prostate cancer. A man with one close relative with prostate cancer – for example, a father or a brother – is twice as likely to develop prostate cancer as a man with no family history of the disease.

If two close male relatives are affected, a man’s lifetime risk of developing prostate cancer is increased five-fold.

 

The genetic fault

Several inherited gene changes seem to raise prostate cancer risk, but they probably account for only a small percentage of cases overall.

Inherited mutations of the BRCA1 or BRCA2 genes raise the risk of breast and ovarian cancers in some families. Mutations in these genes (especially in BRCA2) may also increase prostate cancer risk in some men.

Men with Lynch syndrome (also known as hereditary non-polyposis colorectal cancer, or HNPCC), a condition caused by inherited gene changes, have an increased risk for several cancers, including prostate cancer.

 

Managing risk

There are tests available to detect defects in the BRCA2 gene, as well as the genes associated with Lynch syndrome.

 

About 5 to 10 percent of all prostate cancers diagnosed are hereditary, meaning that an increased risk for the disease runs in the family.

 

7. Pancreatic cancer

There will be approximately 53,670 cases of cancer of the pancreas diagnosed in 2017.

In some of these families, the high risk is due to an inherited syndrome (explained below). In other families, the gene causing the increased risk is not known. 

 

The genetic fault

The following gene abnormalities can cause pancreatic cancer:

  • Hereditary breast and ovarian cancer syndrome, caused by mutations in the BRCA1 or BRCA2 genes.
  • Familial atypical multiple mole melanoma syndrome, caused by mutations in the p16/CDKN2A gene.
  • Familial pancreatitis, usually caused by mutations in the PRSS1 gene.
  • Lynch syndrome, also known as hereditary non-polyposis colorectal cancer, most often caused by a defect in the MLH1 or MSH2 genes.
  • Peutz-Jeghers syndrome, caused by defects in the STK11 gene. This syndrome is also linked with polyps in the digestive tract and several other cancers.
  • Von Hippel-Lindau syndrome, caused by mutations in the VHL gene. It can lead to an increased risk of pancreatic cancer and carcinoma of the ampulla of Vater.
  • Wermer syndrome is caused by a defect in the MEN1 and can cause pancreatic cancer.

 

Managing risk

Genetic testing is available for Hereditary breast and ovarian cancer syndrome, Von Hippel-Lindau syndrome, Wermer and Lynch syndromes. For people in families at high risk of pancreatic cancer, newer tests for detecting early pancreatic cancer may help. One of these is called endoscopic ultrasound. This test is not used to screen the general public, but it might be used for someone with a strong family history of pancreatic cancer or with a known genetic syndrome that increases their risk.

 

Inherited gene changes (mutations) can be passed from parent to child. These gene changes may cause as many as 10 percent of pancreatic cancers.

 

8. Stomach cancer

28,000 new cases of stomach cancer will be diagnosed in 2017.

An estimated one percent to three percent of cases of gastric cancers are hereditary diffuse gastric cancer (HDGC), an inherited cancer syndrome that leads to an increased risk for both diffuse gastric cancer and lobular breast cancer.

 

The genetic fault

Some inherited conditions may raise a person’s risk of stomach cancer.

  • Hereditary diffuse gastric cancer greatly increases the risk of developing stomach cancer. While rare, this condition raises the cancer risk among affected people to 70 to 80 percent.
  • Lynch syndrome is an inherited genetic disorder that increases the risk of getting stomach cancer. This disorder is caused by a defect in either the MLH1 or MSH2 gene.
  • People with familial adenomatous polyposis (FAP) have a slightly increased risk of getting stomach cancer.
  • People who carry mutations of the inherited breast cancer genes BRCA1 or BRCA2 may also have a higher rate of stomach cancer.
  • People with Li-Fraumeni syndrome have an increased risk of several types of cancer, including developing stomach cancer at a relatively young age. Li-Fraumeni syndrome is caused by a mutation in the TP53 gene.
  • People with this Peutz-Jeghers syndrome (PJSS) have an increased risk of cancer of the stomach and several other organs. This syndrome is caused by mutations in the gene STK1.

 

Managing risk

Testing is available for hereditary breast and ovarian cancer syndrome, Li-Fraumeni syndrome, Lynch syndrome, and familial adenomatous polyposis.

 

Approximately 10 percent of gastric cancer cases are hereditary.

 

9. Thyroid cancer

While 56,870 people are estimated to be diagnosed with thyroid cancer in 2017, just 2,010 will die as the disease is quite treatable with early detection

 

The genetic fault

Familial medullary thyroid carcinoma results from inheriting a mutation in the gene called RET.

Those with familial adenomatous polyposis, caused by defects in the gene APC, have an increased risk of papillary thyroid cancer.

People with Cowden disease have an increased risk of thyroid problems and certain benign growths (including some called hamartomas). They also have an increased risk of cancers of the thyroid, uterus, breast, as well as some others. The thyroid cancers tend to be either the papillary or follicular type. This syndrome is most often caused by defects in the gene PTEN.

Carney complex, type I syndrome may cause benign tumors and hormone problems. There is also an increased risk of papillary and follicular thyroid cancers. This syndrome is caused by defects in the gene PRKAR1A.

Familial nonmedullary thyroid carcinoma is often seen at an earlier age. The papillary type of thyroid cancer most often runs in families. Genes on chromosome 19 and chromosome 1 are suspected of causing these familial cancers.

 

Managing risk

People with a family history of medullary thyroid cancer should consider genetic testing when they are young to see if they carry the gene changes linked to MTC. For those who may be at risk but don’t get genetic testing, blood tests can help find MTC at an early stage, when it may still be curable. Thyroid ultrasounds may also be done in high-risk people. Genetic testing is available for Cowden Syndrome and familial adenomatous polyposis.

 

Two out of 10 medullary thyroid carcinomas are a result of an inherited gene abnormality.

 

Approximately five percent of people with papillary thyroid cancer inherited the disease.

 

10. Uterine (endometrial) cancer

Uterine cancer is the 10th most common cancer with 61,380 cases estimated to be diagnosed in 2017.

 

The genetic fault

Of hereditary uterine cancers, approximately 50 to 70 percent are associated with the Lynch syndrome/HNPCC which is caused by the inheritance of a predisposing mutation in a single gene. 

 

Managing risk

A test is available to detect the defect resulting in HNPCC.

Women who have Lynch syndrome have a very high risk of endometrial cancer and may choose to have a hysterectomy after finished having children to prevent endometrial cancer. One study found that none of 61 women with HNPCC who had prophylactic (preventive) hysterectomies were later found to have endometrial cancer, while 1/3 of the women who didn't have the surgery were diagnosed with endometrial cancer over the next seven years.

 

For 10 percent of women with uterine cancer, the disease is a result of an inherited gene defect.

 

If you or a loved one is facing a cancer diagnosis for an inherited or non-inherited cancer, compassionate, quality care is available from Dr. Perez and Sierra Nevada Cancer Center. With locations in Carson City, Stateline, Gardnerville and Fallon, the care you need is close by. To schedule an appointment, call (775) 883-3336.

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