USPSTF mammography guidelines spark debate

The US Preventive Services Task Force (USPSTF)’s updated recommendations on mammography are open for public comment, prompting renewed debate about the value of screening in women younger than age 50. The draft document reaffirms the panel’s controversial finding in 2009 that decisions about baseline mammography at ages 40 to 49 should be individualized and, for the first time, reviews evidence for tomosynthesis or 3-D mammography.

Grading the evidence a B, the USPSTF came out in favor of biennial screening mammography for women aged 50 to 74. The panel rated a C evidence supporting screening mammography in women aged 40 to 49, commenting that, “The decision to start screening mammography in women prior to age 50 years should be an individual one. Women who place a higher value on the potential benefit than the potential harms may choose to begin biennial screening between the ages of 40 and 49 years.” Evidence was insufficient, the USPSTF recommendations indicate, to support screening mammography in women aged 75 years and older.

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In assessing new technology for screening, the panel found insufficient evidence to recommend use of 3-D mammography for primary screening. A similar comment was made about use of ultrasound, magnetic resonance imaging, 3-D mammography or other modalities for screening specifically in women with dense breasts. The USPSTF did not update its recommendation against clinicians teaching breast self-examination to patients (D recommendation) but said it is important for women to report lumps or other significant changes in their breasts to their healthcare provider.

In response to release of the draft recommendation statement by the USPSTF, The American College of Obstetricians and Gynecologists (ACOG) issued a Practice Advisory to Fellows, noting that the update is in keeping with its practice bulletin on breast cancer screening, particularly regarding women aged 40 to 49, and indicating that ACOG plans to submit formal comments to the Task Force.  

Autism linked with pregnancy complication

A study of more than 300,000 children points to a potential new risk factor for autism spectrum disorder (ASD): in utero exposure to gestational diabetes mellitus (GDM).The findings, by researchers from Kaiser Permanente, were published in the Journal of the American Medical Association.

In the retrospective longitudinal cohort study, 322,323 singleton children of various ethnicities were tracked from birth until date of clinical diagnosis of ASD, last date of continuous KPSC plan membership, death due to any cause, or December 31, 2012 (whichever came first). The births were from 1995 to 2009 and the pregnancy exposures were as follows: preexisting maternal type 2 diabetes (n = 6496), GDM at 26 weeks’ gestation or earlier (n = 7456), GDM after 26 weeks’ gestation ( n = 17,579), or no diabetes (n = 290,792).

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ASD was diagnosed in 3388 of the children, 115 of whom had been exposed to preexisting type 2 diabetes, 130 to GDM at ≤26 weeks, 180 to GDM at >26 weeks, and 2963 of whom were unexposed. The unadjusted annual incidences of ASD were 3.26, 3.02, 1.77, and 1.77 per 1000, respectively. The birth year adjusted hazard ratios (HRs) were 1.59 (95% confidence interval [CI], 1.29-1.95) for preexisting type 2 diabetes, 1.63 (95% CI, 1.35-1.97) for GDM diagnosed at 26 weeks or earlier, and 0.98 (95% CI, 0.84-1.15) for GDM diagnosed after 26 weeks, in comparison to no exposure.

After adjusting for maternal age, parity, race/ethnicity, sex of the child, history of comorbidity, education, and household income, maternal preexisting type 2 diabetes was not significantly associated with ASD in a child (HR, 1.21; 95% CI, 0.97-1.52). However, GDM diagnosed at 26 weeks or earlier remained significantly associated (HR, 1.42; 95% CI, 1.15-1.74). Exposure to antidiabetic medication was not independently associated with ASD risk. The results also were not affected if a mother or sibling had ASD, a mother smoked, or by pre-pregnancy body mass index or pregnancy weight gain.

Editing of genome in embryos sparks debate

Rumors that Chinese researchers had successfully edited the human genome in embryos were proven true when authors from Sun Yat-sen University published results of the work in Protein & Cell, an online journal.

The researchers used embryos from fertility clinics which were nonviable because they had been fertilized by 2 sperm. For the modification, the team targeted a gene responsible for β-thalassemia. They used CRISPR/Cas9, an enzyme complex that binds and splices DNA in specific locations. The enzyme complex has been studied in adult cells and animal embryos but this is the first study in which it has been used on human embryos. 

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CRISPR/Cas9 was injected into 86 embryos, 71 of which survived the procedure and 54 of which were subjected to genetic testing. Of them, only 28 were cleaved by Cas9, for an efficiency of approximately 52%. Seven embryos contained four identical point mutations in tandem.

The ethics of the work have been questioned by the scientific community. An editorial in Nature sounded a note of warning about a need for discussion about where the science is going. The lead researcher for the study, Junjiu Huang, said that his team did not continue their research because they considered the technology too immature.