Genetic testing for cancer susceptibility

‘Genetic testing that provides greater diagnostic certainty with important prognostic and therapeutic implications for many diseases.

Also known as DNA testing, allows the determination of bloodlines and the genetic diagnosis of vulnerabilities to inherited diseases.

Approximately 10% of patients diagnosed with cancer, have a germ line gene variant that increases susceptibility to cancer.

Recommendations for cancer risk, surveillance, prophylactic surgery, and in some cases radiotherapy can be influenced by genetic testing.

More than 100 genes are associated with increase susceptibility to cancer. 

The prevalence of germline genetic variants varies by cancer type range from 4-6% of patients with lung cancer, esophageal cancer and head and neck cancer,  to 30% for male patients with breast cancer.

The most common germline pathologic variant mutations occur in BRCA1, BRCA2 with increased ovarian, breast, Pancreatic, and prostate cancers.

.Germline, pathogenic variants of MLH1, MSH2, MSH6, and PM52 (Lynch syndrome) are associated with increased risk of colorectal, endometrial, and other cancers.

Testing patients with cancer for gene variations, may provide an optimal treatment and may help identify relatives who may have inherited genes that increase their cancer susceptibility.

Presently practice guidelines recommend testing for inherited cancer susceptibility genes for all patients with ovarian, male breast, and pancreatic cancer. 

For other cancer types, including female breast, prostate and colorectal cancers practice guidelines advocate testing for all 4patients or increasing subsets of patients.

Identifying a high risk variant, such as BRCA1/BRCA2 may encourage some women to select risk reducing bilateral mastectomy or risk reducing salpingo-oophorectomy. 

Patients with the variant predisposing genes are candidates for more frequent or intensive cancer screening such as increased colonoscopy frequency in Lynch syndrome, breast magnetic resonance imaging in females with BRCA1 and BRCA2 genetic variants, and whole body MRI imaging in patients with Li-Fraumeni syndrome. 

Leave a Reply

Your email address will not be published. Required fields are marked *