How Does Family History Affect Cancer?

The rising incidences of cancer have made it important for us to be vigilant about our health. It has been proven medically that if cancer is detected at an early stage -stage I & II , then the chances of cure and treatment along with full recovery are very high. For early cancer detection & for people at greater risk of cancer, PHC-Preventive Health Care plays a major role. Preventive Health Check is particularly important for the people who have a family history of cancer.

Hereditary Cancers:

Almost all cancers are caused by damage or mutation in their genes, which, may be acquired from environmental exposure, dietary factors, hormones or through normal aging. In 90% of cases, these genes are not passed from parents to children. These are known as sporadic mutations and the cancers that they cause are called as sporadic cancers. But 5-10% of cancers are caused by gene mutations which are inherited from one or both parents & passed on to the children .These are hereditary or germline mutations & these cancers are known as hereditary or familial cancers.

People /children, who carry gene mutations have a higher risk of developing cancer at an earlier age or at some point in their life time.

Some of the common such cancers, which run in families, are:

• Breast cancer
• Ovarian cancer
• Colo-rectal cancer (cancer of large intestine )
• Prostate cancer
• Lymphoma
• Melanoma
• Retinoblastoma

Breast, ovary & colo-rectal carcinoma have well established gene mutation studies.Mutation of BRCA 1 & BRCA2 Genes is responsible for 85% of hereditary breast cancers.

Estimated life time risk for developing breast cancer in woman with BRCA1 & BRCA2 mutation is 56-87% & risk for developing-bilateral /contralatral breast cancer is about 20-40%. These statistics make a preventive health check for women with breast cancer history in their family a necessity. Mutation in these genes confers about 20-40% increased life time risk for developing ovarian cancer. Hence the presence of gene mutation for breast cancer can trigger ovarian cancer.

However as stated above, other environmental and lifestyle factors can also cause breast cancer other than genetic BRCA1 & BRCA 2 gene mutations.

• Increasing age
• Early menarche
• Late menopause
• Nulliparity
• First birth after the age of 30
• Atypical lobular hyperplasia or Atypical ductal hyperplasia
• Prior breast biopsies
• Long term postmenopausal estiogen replacement
• Early exposure to ionizing radiation

Other Familial Cancers:

Familial cancer syndromes associated with colo-rectal cancers are familial adenomatous polyposis (FAP).It is an autosomal dominant inherited syndrome with more than 90% penetrance, manifested by hundreds of polyps developed by late adolescence .The risk of developing invasive cancer is almost 100% .So such patients should start getting colonoscopy at an earlier age- say by 20yr of age & should undergo Total Collectomy on development of significant polyps .

Other familial cancer syndromes are hereditary non -Polyposis Colo Rectal Cancer (HNPCC), Gardner's Syndrome, Turcot's Syndrome, Peutz-Jeghers Syndrome, Juvenile Polyposis.

Cancer Assessment & Conclusion:

For breast cancer risk assessment, we have the GAIL model & IBIS model, which take into consideration ,all the risk factors, apart from BRCA1 & BRCA 2 gene mutation. These models calculate the over all life time risk of development of breast cancer for any lady. For this, you have to consult a specialist experienced in area of hereditary cancers, cancer risk assessment, genetic counseling & testing.

To conclude, all people with cancers in their family should undergo genetic testing & counseling, to detect high risk individuals should take adequate measures & treatment.