A recent study led by researchers at the University of Texas MD Anderson Cancer Center suggests that, in addition to genetically profiling tumors to assist in clinical treatment decision making, the profiling of normal DNA can also offer insight into inherited mutations that might be critical for patients and their families. Findings from this study will be presented on June 1 by Dr. Funda Meric-Bernstam during the 2015 American Society for Clinical Oncology (ASCO) Annual Meeting, to be held in Chicago.

The research team has genetically profiled 202 genes in tumor and normal DNA samples from 1,000 patients with advanced cancer. Among the selected genes, harmful mutations in 19 of them had been previously linked to cancer development, namely in TP53, BRCA1 and BRCA2 genes. Although sequencing normal tissue is not a common practice in research, by comparing the results with tumor tissues, it is possible to discriminate between inherited (germline) mutations and those present only in the tumor.

“This is an opportunity to identify germline mutations that could have contributed to a patient’s cancer development and may be a heritable cancer syndrome that would put the patient’s family members at risk,” explained Dr. Meric-Bernstam in the news release. “Therefore, it would be important to inform the patient and their family members so they can get further testing, genetic counseling and risk-reducing efforts as needed.”

The team found that of the 1,000 patients analyzed, 99.9% had at least one germline variant in one of the 19 cancer-related genes, and 43 patients had mutations considered likely to be harmful. In more than half of these patients (23 individuals), it was not known that they carried such mutations, emphasizing the importance of this approach.

In total, 99% of the patients enrolled in this study reported the desire to know about any possible harmful mutation that they could have. Patients who were found to have pathogenic germline mutations are now following a formal genetic counseling, which is a critical component of the study. The team believes that such genetic information is valuable in terms of future patient care and should be handled accordingly.

[adrotate group=”15″]“Patients have been very interested and, overall, grateful to be part of this protocol, recognizing the importance of this finding, especially for their families,” noted Dr. Meric-Bernstam. Once family members become aware of the possibility of carrying harmful inherited mutations, they can get tested for those specific gene mutations.

The research team proposes that cancer patients who already have their tumors sequenced might benefit from additional sequencing to normal tissue samples. Dr. Meric-Bernstam concluded “it is important to consider analyzing the normal data as well in order to capitalize on the opportunity to inform the patients and their families of the findings.”

The team will complete the analysis for all the patients included in this study and, after identifying the ones with potentially harmful mutations, determine the best way to take the most advantage out of all genetic data obtained, and to inform and clarify patients and their families about the results.