By Sara Ragi, Cornell University
A cancer diagnosis is fraught with fear and confusion often centered on the plethora or, in unfortunate cases, lack of treatment options. However, more recently, individuals with cancer diagnoses are becoming informed by their physicians that there are more personalized treatment options that can offer targeted clinical therapy, or in some cases preventative interventions based on a field of medicine known as genomic medicine.
Genomic information through DNA sequencing has provided databases documenting key genomic changes in a variety of cancers, and it is through this information that diagnosis and treatment are currently being shaped, developed and refined.
Cancer is a disease of the genome, and each tumor bears a unique marker for its genetic changes. Human DNA contains an estimated 20,000-25,000 genes, each containing the blueprint for specific functioning. Cancer genomics aims to advance personalized medicine through the DNA sequencing and analysis of patient tumors. The goal is to find new genetic mutations and alterations associated with specific cancers, and tailoring treatment based on the unique genetic profile of each patient. Scientists can now sequence an individual’s genome, and they can additionally sequence the genome of tumor cells living within that same individual.
By analyzing the differences between healthy cells and cancerous ones, researchers can identify genetic abnormalities that may be driving the spread of a particular cancer.A genomic tumor assessment begins at diagnosis. The biopsy is sequenced and the genetic sequence is scanned for abnormalities. Researchers and physicians alike are looking for a match between relevant abnormalities with potential treatment. In some instances, those abnormalities may reveal a more aggressive cancer, and this would form the basis for a refined treatment approach.
Cancer Treatment Centers of America (CTCA), Medical Director of Genetic Studies Michael Kayer addressed how the discovery of a mutation may offer clues for intervention. He states, “If we know a tumor is particularly aggressive, we may treat it longer or with a higher disease, or we may watch it more closely.” In the domains of prostate and breast cancers, treatment options are beginning to reflect the advance in cancer genomics.
For those with a prostate cancer diagnosis (approximately 222,000 men in America) one-third to one-half will live with the disease. The Prostate Specific Antigen (P.S.A.) blood test is currently administered as a screening device, which often leads to treatment of all patients who test positive. The P.S.A. has a high false-positive rate that can be misleading often suggesting cancer where there may be none, or where there may be low-risk prostate cancer. Additionally, biopsy pathology reports that confirm prostate cancer often do not address the issue of “how” the cancer detected is likely to behave. Surgery, and radiation, typically prescribed treatment options, often results in serious side effects including incontinence and loss of sexual functioning.
In contrast, researchers in the field of prostate cancer are seeking prostate cancer biomarker tests that can detect the prostate cancers that according to Dr. Otis Brawley, a Chief Medical Officer for the American Cancer Society, “…kill and must be treated, versus those that don’t kill”. Recently, Swedish researchers developed a liquid blood biopsy that analyzes more than 200 genetic markers called “Single Nucleotide Polymorphisms” (S.N.Ps) that are associated with prostate cancer, and six prostate protein markers. Part of their analysis also added in family history, and basic medical information of the patient including age, etc. The new test STHLM3) and the P.S.A. test were administered to 58,000 + men in their 50’s and 60’s with the specific purpose to increase specificity compared with PSA without decreasing the sensitivity to diagnose high-risk prostate cancer. The STHLMC model performed significantly better than PSA alone in detecting high-risk cancer, thus reducing unnecessary biopsies without compromising the ability to diagnose prostate cancer with a Gleason score of age least 7. The study concludes that the use of the STHLMC may be a “…a step towards personalized risk-based prostate cancer diagnostic programs”.
Similarly in the field of breast cancer prevention/diagnosis, cancer genomics is front and center terms of diagnostic tools for millions of women at a cost that may currently challenge insurance companies. BRCA Share was launched in April 2015. This novel gene data sharing initiative provides scientist and commercial laboratories globally with access to BRCA 1 and 2 genetic data. Participants will have to contribute data to the database, and companies pay a fee for access to the data, all of which has enormous potential for diagnostic tools and treatment options to be developed within a shorter time frame. Overall the field of cancer genomics holds the immense potential to revolutionize cancer treatment and pool significant data applicable to more effective cancer therapies.