Handbook of Genetic Counseling/Cancer

Cancer

Cancer Epidemiology Data

• Cancer is the uncontrolled growth of cells. All cancers are genetic, but not all are inherited. It is a multifactorial disorder, caused by both genetic and non-genetic factors.
• Cancer is a very common disease. 1 in 2 men and 1 in 3 women will develop some form of cancer in their lifetimes. The most common cancer sites are lung, breast, prostate, and colon.
• In the U.S., approximately 175,000 new cases of breast cancer are diagnosed each year (50,000 of these are in women under 40).
• In the U.S., 1 in 8 women will develop breast cancer over their lifetimes. Average age of developing cancer is 62. 2/3 of the women will be over 55 years old.
• Genes are on chromosomes and they come in pairs (1 mom, 1 dad). Autosomal dominant, so 50/50 chance of inheriting the gene. Explain tumor suppressor genes, oncogenes, mutations.
• About 5-10% of all breast cancer is hereditary. About 20% of it is familial (combination of different genes and environment). Most cancer is sporadic.
• Familial clustering is more common than hereditary breast cancer. A combination of genes from both sides of the family plus environmental factors.
• Our job is to figure out where your cancer lies. Of the hereditary type, 2/3 is caused by BRCA1 (45%) and BRCA2 (35%) mutations (increases the risk up to 85%).
• Management: mammograms at age 40, physician exam twice a year, self-exams monthly.

Cancer Pedigree Questions

• A pedigree is our "physical exam". Gives us clues as to whether the cancer is hereditary. It's important to know who has AND who doesn't have cancer.
• "Tell me about your experience" or "Tell me what happened"
• Very specific questions about the cancer in different family members
• Age at diagnosis
• Current age & screening practices
• Age at death & specific cause of death
• Primary site of cancer (type, location, stage, laterality)
• Metastasis or any new primary cancers
• Methods of treatment/surgery
• Any types of precancerous lesions
• Ethnic background
• Environmental exposures
• Lifestyle issues (diet, exercise, stress)
• Screening habits of "unaffected" relatives
• Any other medical conditions that may be associated with cancer
• any family hx of early heart attacks, blindness, deafness, birth defects, or multiple miscarriages
• Things that make us suspicious. . .cancer across one or more generations, multiple people affected in the same generation, early age of onset (before 50)
• Need a medical release for pathology reports, clinic notes, autopsy reports, death certificates, etc. for verification.

Notes

The information in this outline was last updated in 2002.