Prostate Cancer & Heredity

Prostate cancer is the most common type of cancer diagnosed among American men, affecting one in six men during their lifetime. In 2008, an estimated 186,000 men will have been diagnosed with prostate cancer, according to the American Cancer Society. Currently, it is the second leading cause of death due to cancer in men. Fortunately, recent improvements in detection and treatment have significantly improved the outlook for men diagnosed with prostate cancer.

• Age

  Prostate cancer occurs more frequently in older men. Only 2 percent of prostate cancers are found in men younger than 56 years of age. Around 28 percent are detected in men 56 to 65 years of age and the other 70 percent are discovered in men older than 65 years.

• Family History

  Family history is the strongest risk factor for prostate cancer. A man with one close relative (such as a father or brother) with prostate cancer has twice the risk of developing prostate cancer as a man with no family history. If two close male relatives (such as a brother and a father) are affected, a man's lifetime risk of developing prostate cancer is increased five-fold.

• Ethnicity

  Prostate cancer risk is about 60 percent higher in African-American men than in Caucasian men.

• Diet

  A diet high in fat and low in vegetables is associated with an increased risk for prostate cancer. The extent to which dietary factors contribute to and/or prevent prostate cancer is currently being researched.

The current recommendation is that all men at average risk should be screened once a year for prostate cancer beginning at age 50. Men who are at an increased risk for prostate cancer should begin screening earlier. African-American men and men with a family history of prostate cancer should begin screening at age 40.

Screening consists of a rectal exam (DRE, or digital rectal exam) and a blood test (PSA, or prostate specific antigen). To perform a DRE, the doctor places his/her gloved finger into the patient's rectum to feel the prostate gland and examine its size, consistency, and shape. Most men say the exam is not painful. The PSA test is done to determine the level of a certain protein made by the prostate. That level increases significantly when a tumor is present, but can also be increased by infection and benign (noncancerous) prostate enlargement. In a PSA test, blood is drawn from a vein in the patient's arm. Usually, these tests are done at the time of a regular checkup. If results of either test are not normal, the doctor will suggest more tests.

Recent studies have concluded that a susceptibility to prostate cancer can be inherited. It estimated that 5 to 10 percent of all prostate cancer cases are considered hereditary. This means that in some families, a genetic predisposition to develop prostate cancer can be passed down from parent to child.

Our bodies are made up of thousands of cells, and each of those cells contains a copy of the inherited information called DNA that is passed down to us from our mothers and fathers. Our DNA is packaged onto structures called chromosomes. Each human cell has a total of 46 chromosomes, which come in pairs -- 23 from the mother and 23 from the father. Each chromosome is made up of thousands of genes, which also come in pairs. Genes are a cell's instructions; genes tell the cell what to do, when to divide, and when to die. An alteration or mutation in one or many genes can interfere with the normal functions of a cell. If a mutation happens in a gene that controls cell growth and division, it can cause specific cells to grow uncontrollably. All cancer occurs when cell growth and division escapes hormonal control.

Cancer usually is caused by mutations in genes that occur randomly in one cell of the body. As we age, all of our cells acquire more mutations, which is why most cancer happens when we are older.

Sometimes, however, a genetic mutation is passed down from parent to child. Individuals with these inherited genetic alterations have an increased risk of developing cancer compared with individuals without them. In addition, the age at which an individual with a genetic mutation develops cancer is usually younger than what would be expected in the general population. Typically, when a genetic mutation that predisposes a person to cancer is being passed down, a family will have multiple generations with multiple individuals diagnosed with the same type of cancer.

Currently there is no clinical testing for genes involved with prostate cancer. Only recently have studies begun to identify such genes. At present, many separate genes are thought to be involved: three on chromosome 1, one on chromosome 17, one on chromosome 20, one on chromosome X, and one on chromosome 8, as well as several others. Additional research is needed to determine to what extent these genes are responsible for hereditary prostate cancer. Understanding how these genes are involved is critical for identifying men at increased risk, implementing proper screening procedures, and developing better treatments.

However, men who are concerned about their hereditary risk because multiple family members have developed prostate cancer -- or there is an early age of diagnosis -- should discuss their concerns with their doctors and consider making an appointment with a trained genetic specialist.