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.