CHAPTER 20: Genetic and Familial Assessment for Hereditary Cancer Syndromes

Around 5%–10% of cancers are hereditary. Genetic testing is helpful to identify high-risk patients and families who may benefit from increased screening, chemoprevention, and risk-reducing surgeries. HBOC is an autosomal dominant condition caused by a mutation in BRCA1 or BRCA2. Families with HBOC have combinations of breast, ovarian, prostate, and pancreatic cancers and possibly melanoma, sometimes at younger ages. These families are commonly Ashkenazi Jewish (carrier frequency of 1/40), but this is a differential diagnosis regardless of ancestry (1/400–1/800 in Europeans).

A 60-year-old woman with stage IV pancreatic cancer and a prior history of stage I invasive ductal carcinoma of the right breast at age 39, post-mastectomy, with a family history of ovarian cancer in paternal aunt at age 79 and a paternal male cousin with prostate cancer at age 65 through unaffected uncle. She has two daughters and wants to know whether her children need to get genetic testing.

• Educated genetic counseling process: discussion between genetic counselor, patient, and physician about possible cancer risks and management prior to pursuing genetic testing for educated testing decision, including post-test counseling to discuss the management plan

• Genetic testing to be offered to adults only (age 25 years, as screening begins at this age, although if family planning is earlier, may start as young as age 18 years)

• Offer comprehensive testing to the patient first (prior to family): individuals affected with cancer are more informative testing candidates

  • This will likely include a panel to address breast, ovarian, and pancreatic gene overlap

• Risk assessment: if the patient meets criteria for genetic testing, per NCCN guidelines, offer testing¹

• Management if results are positive^1-7

Patients with suspected hereditary conditions should meet with a genetic counselor and/or physician to pursue genetic counseling and testing (a blood test) to clarify their cancer risk management recommendations. There are several tests to choose from, and test selection should take into consideration the cancer primaries ...