Sometimes cancers tend to run in families, that is they tend to affect multiple members of a family. It may be due to common risk factors such as environmental, behavioral, or lifestyle. Or else it may be due to abnormal genes that get transferred fro generations to generations (inherited cancers) .
IN AN INDIVIDUAL PATIENT:
- Multiple primary tumors in same or different organ(s)
- Bilateral primary tumors in paired organs.
- Multifocality within a single organ
- Younger than usual age at diagnosis.
- Rare histology
- Tumors associated with other genetic traits, congenital defects, or inherited precursor lesion
- Tumor associated with cutaneous lesions known to be related to cancer susceptibility
IN THE PATIENT’S FAMILY:
- first-degree relative with the same or a related tumor
- 2 or more first-degree relatives with
- tumors of the same site
- tumor types belonging to a known familial cancer syndrome
- rare tumors
- 3 or more relatives in 2 generations with tumors of the same site or etiologically related sites
What is Genetic Counselling?
Process of communication between genetics professionals and patients with the goal of providing individuals and families with information on the relevant aspects of genetic health, available testing and management options, and support as they move towards understanding and incorporating this information into their daily lives.
It is a communication process between a health care professional and an individual concerning cancer occurrence and risk in his or her family. The process, which may include the entire family through a blend of genetic, medical, and psycho social assessment and intervention
What are the steps of Genetic Counselling?
1. Family History
It is one of the most important component of genetic counselling, and should include atleast 3 generations. Information to be collected is exact diagnosis, age at diagnosis, environmental exposures, and treatment strategies. Further information collected is consanguineous (inbred) relationships in the family, birth defects or mental retardation, and other genetic diseases in the family.
2. Risk Assessment
After a detailed history, next step is assessment of the risk of developing cancer in the person that runs in his/her family. Also, the chance of identification of genetic mutation that may be associated with the particular cancer is assessed.
It is important to differentiate familial from hereditary patterns of cancer in a family. Familial cases are due to environmental factors or by chance, whereas, hereditary ones are due to shared genetic mutations.
Various models are available for breast cancer that help to clinically assess the risk of development of cancer in an individual. One such Risk Interpretation Model is Gail Model that takes into account age of the individual, family history, age at first menses, age at first live birth, and number of previous breast biopsies. There are other similar models, but their accuracy is limited.
3. DNA Testing
It involves actual detection of the culprit mutation, an has a higher accuracy than Risk Interpretation Models. The person affected with a cancer is checked first for the suspected mutation based on family history and clinical risk assessment. If he/she is positive, then other family members are checked for the same.
4. Surveillance and Risk Reduction Strategies.
BREAST AND OVARIAN CANCER
- Breast self examination monthly from 18 yrs
- Clinical breast examination semi annually starting from 25 yrs
- Mammography or MRI scan of breast annualy from 25 yrs of age. Or at the earliest age of onset of cancer in family.
- For ovarian ca transvaginal USG semi annualy combined with CA125 levels. From age of 25 to 35 yrs.
Risk reduction strategies:
- Prophylactic bilateral mastectomy reduces the breast cancer risk by 90%.
- Prophylactic tamoxifen reduces the breast cancer risk
- Prophylactic bilateral salphingo-oophorectomy reduce the risk of ovarian, tubal cancer risk by 80%.
- Familial Adenomatous Polyposis (FAP) – Colonoscopy annualy beginning at the age of 10-12 yrs.
- Heriditary non-Polyposis Colon Cancer (HNPCC) – Colonoscopy every 1-2 years beginning at the age of 20-25 yr or 10 yrs younger than the earliest case in family, whichever comes first.
Risk Reduction strategies:
- FAP – The three current surgical options for patients with FAP are
- total proctocolectomy with permanent ileostomy (TPC),
- total colectomy with ileorectal anastomosis (IRA), and
- proctocolectomy with ileal pouch-anal anastomosis (IPAA).
- HNPCC – Prophylactic subtotal colectomy with ileoanal anastomosis.
What are the various Familial cancer susceptibility syndromes?
- Gorlin syndrome
- Bloom syndrome
- Fanconi anemia
- Hereditary melanoma
- Xenoderma Pigmentosum
- Cowden syndrome
- Familial Adenomatous Polyposis (FAP)
- Familial juvenile polyposis
- MYH-associated polyposis
Breast and Ovarian Cancer
- Heriditary Breast Ovarian Cancer (BRCA1 and BRCA2)
- Cowden syndrome,
- Li Fraumeni
Endocrine and Neuroendocrine Tumors
- Familial hyperparathyroidism
- Familial Medullary Thyoid Cancer (MTC)
- MEN 1, 2A, 2B (Multiple Endocrine Neoplasias)
Renal Cell Cancer
- Von Hippel-Lindau Syndrome
- Hereditary papillary renal cancer (HPRC)
- Birt-Hogg-Dube syndrome (BHD)
- Hereditary leiomyomatosis and RCC (HLRCC)
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