Germline and Somatic Testing:
The decline in cost and the expansion in the availability of NGS has
enabled the application of germline and somatic testing in routine
clinical practices51 5253. While Polygenic Risk Scores and Decipher help
determine the risk of recurrence and prognosis from primary prostate
cancer, germline, and somatic testing determine heritable risk and guide
treatment decisions in advanced disease settings54.
The assessment of germline genetics helps assess an individual“s
specific cancer risk, aids family cancer screening, and also informs
treatment possibilities54. Somatic mutations are
acquired over the course of an individual lifespan. Identification of
somatic mutation requires the sequencing of DNA from tumor tissue,
circulating tumor cells or circulating tumor DNA (ctDNA) in the blood.
Since somatic mutations are often subjected to change over time due to
genetic instability, repeated somatic testing might be appropriate as
the cancer progresses through
treatment54.Identification of germline and somatic
mutations can help guide treatment options in the advanced disease
setting. Tumor genetic testing can identify both somatic and germline
mutations. However, tumor testing should not be performed as a
substitution for germline testing given challenges in distinguishing
between somatic and germline mutations. In the event that there is an
identification of somatic mutation which has implication of cancer
predisposition (BRCA1), then a confirmatory germline test is highly
recommended55 54.