Germline genetic testing is used by many labs to evaluate a patient’s predisposition to hereditary cancer, and produces excellent results in its analysis of many genetic conditions. However, when germline testing is combined with tumor testing as a single paired test, it may yield even more helpful results in certain situations. Specifically, for diagnosing or ruling out Lynch syndrome, or finding patients with homologous recombination deficiency (HRD) in their ovarian cancer, pairing both germline and tumor tests produces comprehensive results that allow for more informed diagnoses and treatments.
For women with epithelial ovarian cancer, paired tumor/germline testing can be utilized to determine if they are eligible for treatment with a PARP inhibitor. This treatment can offer hope, as it is a targeted treatment option for specific ovarian cancer patients. The germline testing can identify hereditary cancer, which can determine a personal risk for other cancers, as well as possible increased cancer risks for family members. Germline genetic testing, particularly of BRCA1/2, is recommended for all women with epithelial ovarian cancer, as up to 25% of ovarian cancers are caused by an inherited mutation.1,2 The tumor testing can provide further insight into effective treatment options, such as the eligibility for PARP inhibitor treatment. Women with epithelial ovarian cancer need timely, targeted treatment, as the 5-year relative survival rate is 45%.3 Paired tumor/germline testing gives clinicians the complete picture needed to provide patients with the best care possible.
Paired tumor/germline testing can also benefit those with colorectal or endometrial cancer who are suspicious for a diagnosis of Lynch syndrome, such as those with abnormal microsatellite instability/immunohistochemistry (MSI/IHC). Lynch syndrome is the most common cause of hereditary colorectal cancer, and paired testing can greatly impact a patient’s management. For this condition, germline testing can confirm a diagnosis of Lynch syndrome; however, these results are sometime discordant with MSI/IHC results. For example, some patients may have abnormal MSI/IHC, suggesting Lynch syndrome, but normal germline genetic testing results, causing confusion for the patient and their healthcare provider regarding their cancer risks and management needs. Up to 70% of cases of discordant results can be explained by 2 somatic (tumor) mutations in a Lynch syndrome gene.4 Using paired tumor/germline testing can bring clarity to a Lynch syndrome diagnosis, as it can confirm through germline or possibly rule out through tumor, allowing for more informed management recommendations.
While both tests serve different patient populations, the paired tumor/germline testing options can provide all parties involved with the most informative results possible. Combining germline and tumor testing can create a more complete genetic picture, bringing clarity to diagnosis, treatment and management. Additionally, these paired tests increase efficiency, as clients do not have to order separate germline and tumor testing to receive relevant information.
Ambry is the first commercial laboratory to offer paired tumor/germline testing for both of these conditions through TumorNext-HRD and TumorNext-Lynch. You can read more about our initial announcement of these two tests here.
To learn more about TumorNext-HRD, click here. For more information on TumorNext-Lynch, click here.
References
1. NCCN Clinical Practice Guidelines in Oncology®. Genetic/Familial High-Risk Assessment: Breast and Ovarian. V1.2017.
2. SGO Clinical Practice Statement: Genetic Testing for Ovarian Cancer. October 2014
3. 2017 American Cancer Society©. Ovarian Cancer: Survival Rates for Ovarian Cancer, by Stage. Accessed July 24, 2017. Available from https://www.cancer.org
4. Haraldsdottir S, et al., Gastroenterology. 2014 December;147(6):1308-16
