Parental Smoking Linked to Genetic Changes Found in Childhood Cancer

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Smoking by either parent helps promote genetic deletions in children that are associated with the development and progression of the most common type of childhood cancer, according to research headed by UC San Francisco. While the strongest associations were found in children whose parents smoked during their infancy, these deletions were also noted in the offspring of parents who may have quit smoking even before conception.

The link between acute lymphoblastic leukemia (ALL) and parental smoking – especially paternal smoking – has already been established, but this is the first study that points to specific genetic changes in the tumor cells of children with the cancer, said co-first author Adam de Smith, PhD, assistant researcher in the Department of Epidemiology and Biostatistics at the UCSF Helen Diller Family Comprehensive Cancer Center.

“With more smoking among the parents, we saw more deletions within the child’s ALL cells at diagnosis,” de Smith said.

DNA Error Causes Unchecked Growth

ALL, which is one of two primary types of leukemia in children, occurs when white blood cells called lymphocytes develop errors in their DNA, causing unchecked growth that crowds out healthy cells. Genetic deletions found in ALL patients wipe out cell-cycle control proteins and critical transcription factors required for the development of cells that play a key role in the immune response.

Approximately 3,100 children and teens are diagnosed each year with ALL, according to the American Cancer Society. While the five-year survival rate is high – 90 percent for children under 15 and 75 percent for 15- to 19-year-olds, according to the National Cancer Institute – long-term effects, which include an elevated risk for secondary cancers, may be serious and life threatening.

In the study publishing April 1, 2017, in the journal Cancer Research, UCSF scientists and their colleagues at UC Berkeley, Stanford University and University of Southern California looked at pre-treatment tumor samples from 559 ALL patients collected by the California Childhood ...

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