Study Shows DNA Sequencing Brings Greater Precision to Childhood Cancer

Dr. Plon with a patient and her family

Caption: Baylor’s Sharon Plon consults with a family at the Texas Children’s Cancer Center in Houston.
Credit: Paul V. Kuntz/Texas Children’s Hospital

An impressive number of fundamental advances in our understanding of cancer have occurred over the past several decades. One of the most profound is the realization that cancer is a disease of the genome, driven by a wide array of changes in DNA—some in the germline and affecting all cells of the body, but most occurring in individual cells during life (so-called “somatic mutations”). As the technology for sequencing cancer genomes has advanced, we are learning that virtually all cancers carry a unique set of mutations. Most are DNA copying errors of no significance (we call those “passengers”), but a few of them occur in genes that regulate cell growth and contribute causatively to the cancer (we call those “drivers”). We are now learning that it may be far more important for treating cancer to figure out what driver mutations are present in a patient’s tumor than to identify in which organ it arose. And, as a new study shows, this approach even appears to have potential to help cancer’s littlest victims.

Using genomic technology to analyze both tumor and blood samples from a large number of children who’d been newly diagnosed with cancer, an NIH-funded research team uncovered genetic clues with the potential to refine diagnosis, identify inherited cancer susceptibility, or guide treatment for nearly 40 percent of the children [1]. The potential driver mutations spanned a broad spectrum of genes previously implicated not only in pediatric cancers, but also in adult cancers. While much more work remains to determine how genomic analyses can be used to devise precise, new strategies for treating kids with cancer, the study provides an excellent example of the kind of research that NIH hopes to accelerate under the nation’s new cancer “moonshot,”  a research initiative recently announced by the President and being led by the Vice President.

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Hereditary Breast and Ovarian Cancers: Moving Toward More Precise Prevention

Homologous Hope sculpture

Caption: “Homologous Hope” sculpture at University of Pennsylvania depicting the part of the BRCA2 gene involved in DNA repair.
Credit: Dan Burke Photography/Penn Medicine

Inherited mutations in the BRCA1 gene and closely related BRCA2 gene account for about 5 to 10 percent of all breast cancers and 15 percent of ovarian cancers [1]. For any given individual, the likelihood that one of these mutations is responsible goes up significantly in the presence of  a strong family history of developing such cancers at a relatively early age. Recently, actress Angelina Jolie revealed that she’d had her ovaries removed to reduce her risk of ovarian cancer—news that follows her courageous disclosure a couple of years ago that she’d undergone a prophylactic double mastectomy after learning she’d inherited a mutated version of BRCA1.

As life-saving as genetic testing and preventive surgery may be for certain individuals, it remains unclear exactly which women with BRCA1/2 mutations stand to benefit from these drastic measures. For example, it’s been estimated that about 65 percent of women born with a BRCA1 mutation will develop invasive breast cancer over the course of their lives—which means approximately 35 percent will not. How can women in this situation be provided with more precise, individualized guidance on cancer prevention? An international team, led by NIH-funded researchers at the University of Pennsylvania, recently took an important first step towards answering that complex question.

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