Hereditary nonpolyposis colorectal cancer

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at June 28, 2016
StartDiseasesHereditary nonpolyposis colorectal cancer

Lynch syndrome is a genetic disorder which is characterized by an increased risk of developing certain types of cancer, often at earlier ages than normal in patients with the condition. Also called hereditary nonpolyposis colorectal cancer (HNPCC), this condition affects both men and women in equal measure and does not affect any particular race or ethnicity more so than another.

Contents

Definition & Facts

Lynch syndrome is believed to affect around one million Americans. According to Lynch syndrome International, the condition is not rare but is, however, extraordinarily under-diagnosed as only about 5 percent of that number is estimated to have been identified through genetic testing. Of the approximately 140,000 new cases of colon cancer/colorectal cancer which are diagnosed in the United States each year, anywhere from 3 to 5 percent are caused by Lynch syndrome.

Patients with the genetic mutation can have up to an 85 percent chance of developing cancers associated with Lynch syndrome. Additionally, a child born to one Lynch syndrome parent has a 50 percent risk of inheriting that same genetic mutation.

Symptoms & Complaints

There are no outward signs or symptoms of Lynch syndrome itself because the genes which are mutated do not impact a patient’s appearance, behavior, or health unless that person actually develops a cancer associated with Lynch syndrome. Therefore, the only signs or symptoms which someone with the condition may experience are those which result from one of the several types of cancer for which they are at risk.

Those who are diagnosed with Lynch syndrome should make themselves highly knowledgeable about the early warning signs for colorectal cancer, for which the risk is greatest, but also for stomach cancer, small intestine cancer, liver cancer, endometrial cancer, ovarian cancer, gallbladder duct cancer, bladder cancer, brain cancer, skin cancer, and breast cancer.

Causes

As previously mentioned, there is no particular gender, race, or ethnicity that has a higher incidence of Lynch syndrome than any other and the only cause of the disease is a genetic mutation inherited from one’s family. The mutation impacts repair genes which are vital to the process of cell division within the human body.

Prior to a cell dividing, all of its DNA is replicated for the newly formed cell. As that genetic material is copied, it is normal for errors to occur and our body has a set of genes which are responsible for DNA repair or correcting those errors. Lynch syndrome prevents those repair genes from doing their job. This allows incorrect genetic material to be replicated over and over within the body resulting in an ever-increasing number of abnormal cells. It is these abnormal cells which can become cancerous.

For someone with Lynch syndrome, the lifetime risk of developing cancer in mid adulthood (ages 40-60) increases 52 to 85 percent for colorectal cancer, 25 to 60 percent for endometrial cancer, 6 to 13 percent for gastrointestinal cancer, and 4 to 12 percent for ovarian cancer. For female Lynch syndrome patients who develop ovarian cancer, about 30 percent of them will develop it before the age of 40.

Diagnosis & Tests

The diagnosis and treatment of resulting cancers are no different for those with Lynch syndrome than for any other cancer patient. However, diagnosis, treatment, and prevention for Lynch syndrome itself is an interconnected, three-fold approach which can neither be separated into categories nor be replicated from patient to patient.

The first step is an exhaustive examination of an individual’s family medical history and medical history. If a person can identify two people in their family who have been diagnosed and treated for a cancer associated with Lynch syndrome, genetic testing may be in order. There are a variety of tests which can identify whether the genetic mutation is present and a geneticist or genetic counselor can help guide this process.

It is important to remember, though, that a diagnosis of Lynch syndrome does not guarantee that a person will develop cancer nor does it mean that any particular cancer will be inherited. What is passed down between generations is an increased risk.

Treatment & Therapy

Once a person is diagnosed with a Lynch syndrome mutation, treatment and prevention are essentially one in the same. Because medical science has not yet identified a way to correct the gene mutation which causes Lynch syndrome, the best course of action is a combination of healthy lifestyle choices, which can deter the onset of some cancers, and highly targeted, routine medical cancer screening which is designed to catch likely cancers in the earliest stages of their development.

Lifestyle changes which may be implemented include eating a diet low in fat and high in fiber with a minimal amount of red meat. Regular physical exercise has been shown to decrease overall cancer risk and may be suggested as part of a multi-pronged prevention strategy for Lynch syndrome patients.

Women who are diagnosed with the condition may wish to consider having children as early as possible since 2 to 3 percent develop ovarian cancer before the age of 35. Other strategies may include chemoprevention or chemoprophylaxis which is the use of medicine or natural agents to inhibit the development of certain cancers. These may include the use of oral contraceptives to prevent endometrial or ovarian cancers and/or COX-2 inhibitors to prevent colon cancer.

Prevention & Prophylaxis

There is no way to prevent inheriting the Lynch syndrome’s gene mutation from one's parent. However, one who has been diagnosed with the genetic condition can rely upon comprehensive surveillance through routine medical screening to improve their prognosis and increase their longevity. Among these strategies are:

  • Colonoscopy every two years beginning between ages 20 and 25 or 10 years before the earliest age at which a person in one’s family had been diagnosed with cancer (whichever is earliest).
  • Routine esophagogastroduodenoscopy (EGD), which is a scope of the stomach and small intestine, starting at age 30.
  • Urine cytology, which checks for abnormal or potentially cancerous cell growth in the urinary tract, starting between ages 30 and 35.

Additional preventative measures for women may include