Cancer Genetics

Cancer Genetics

All cancers develop as a result of a gene mutation. However, only 5-10% of most cancers are caused by a single mutation in a dominant gene (pattern seen in hereditary cancer). The probability of your cancer being hereditary is generally low without a positive family history of cancer. In a California Survey data, people without a personal history of cancer has 5-7% of developing a hereditary breast cancer, 2.5% of breast-ovarian cancer syndrome, and only 1.1% for hereditary colon cancer. Generally, whites had the highest prevalence, and Asians and Latinos had the lowest prevalence of developing hereditary cancer (Genetics in medicine (2010 ) 12:726).

If hereditary cancer is suspected, genetic couseling is recommended since the result might change your treatment plan and you will need to follow a different surveillance. In addition, it will affect your family members as well. The risk factors that warrant genetic counseling have been well established and they include:

*early age of cancer onset < 50 years old

*multiple family members on the same side of the pedigree (maternal or paternal) with the same cancer, or clustering of cancers in the family

*multiple primary cancers in one individual or cancer on both sides of the body

*ethnicity (Ashkenazi Jewish)

*certain pathology

To assess the possibility that your cancer is hereditary,A� three generation biologic family history is essential including: parents, children, siblings, half-siblings, aunts, uncles, grandparents, great-grandparents, cousins, nieces and nephews.

This application was designed to screen for the probability of herditary cancer risk from your personal cancer based on your age at diagnosis and your family cancer history as an initial risk assessment. The benefit of iIdentifying a genetic cause for your cancer potentially can alter your treatment plan and allow you to receive drugs that target the gene mutation sch BRCA1/2. This application is the first step to identify whether a formal risk assessment and genetic counseling should be undertaken.

There maybe a psychological and emotional consequence that you may experience as a result of undergoing genetic testing, as learning that you may have an inherited gene associated with cancer could be frightening. As such, it is important to recognize that genetic testing is an individual decision and only you can decide if genetic testing is right for you. In addition, this software is not intended to cover all possibilities of your concerns regarding cancer genetic risks, you is recommended to refer all of un-answered questions to your treating physicians. The field of cancer genetic counseling and testing has grown tremendously and covered all aspect of medical illness. This software program is limited to cancer genetics only.

Advance in molecular genetics have identified a numerous genes associated with particular cancers. However, the risk of developing specific cancers is not dependent only on whether you are a carrier of a cancer gene but also on multiple other factors. In other words, a positive test does not always mean that you will develop cancer, and a negative result does not mean that you have no risk of developing cancer. Not all forms of cancer have a hereditary component, but the ones we currently know about are:

1. Breast cancer (up to 10% of breast cancer due to mutations that are passed down in a family (NEJM 2008; 359:2143))

* BRCA1 or BRCA2 genes occurring approximately in 1/400 individuals , more common in Ashkenazi Jews in 1/40 individuals usually carries one of these three founder mutations (2 mutations in BRCA1: 185delAG and 538insC, and 6174delT mutation in BRCA2)

* PTEN gene, P53 gene in 1% of breast cancer, CDH1 gene

2. Colon and rectal cancer

* Genetic susceptibility to colon and rectal cancers include well defined inherited syndromes such as Lynch syndrome (HNPCC), FAP (Familial Adenomatous Polyposis in the APC gene), MAP (MUTYH gene associated polyposis), and other less common syndromes.

3. Osteosarcoma, soft-tissue sarcoma, leukemia, brain cancer, breast cancer, and cancer of the adrenal cortex

*Li-Fraumeni syndrome- mutation in the p53 or CHEK2 gene

OncoGambit application was designed to determine the probability of you having a hereditary cancer risk based on your current diagnosis of cancer, your age, and your family cancer history. This site doesnot calculate the hereditary cancer risk based on you physical findings or birth defects that are known to be associated with rare hereditary cancer syndromes, such as benign skin findings, autism, large head circumference, and thyroid disorders. In addition this model is not designed to calculate your risk of developing cancer based on environmental factors. If environmental factors are the concerns for you, please discuss them with your treating physician.

If you already have family members with a confirmed hereditary cancer gene then you will need to be referred to genetic testing and counseling. Please stop here and see your treating physician. Immediate family members of individuals with BRCA1/2, P53 and PTEN genes have 50% risk of carrying that mutation as well.

In order to use this tool effectively, you need to have a complete knowledge of the biologic family members in three generations (parents, children, siblings, half-siblings, aunts, uncles, grandparents, great-grandparents, cousins, nieces and nephews), their type of cancer and age at diagnosis. The younger the age at diagnosis of cancer, the more likely that a genetic component is present. After having your plan, you then bring it to your treating physician to discuss the details.