A small population of distinctive breast-cancer cells can recapitulate an entire breast cancer when injected into immunodeficient mice. These cells express a unique group of genes, which when expressed in patients with breast cancer portend a poor outcome. Surprisingly, this group of genes is also expressed in prostate and lung cancer and medulloblastoma. This gene group is associated with invasiveness in a range of neoplasms.

The light appearance of epithelium and stroma in a mammogram (mammographic density) can hide the presence of a cancer. A careful study of this problem found that extensive mammographic density is an important risk factor for breast cancer.

Of 300 persons selected for early-onset obesity, hyperphagia, and consanguineous parentage, 8 had mutations in the leptin-receptor gene (LEPR). Biochemical and clinical analyses of the affected subjects suggest that the assay of serum leptin levels is not an appropriate screening tool for LEPR mutations and that the LEPR protein product may not be the only leptin receptor in humans.

The authors report long-term follow-up of otherwise healthy young children with persistent middle-ear effusion who received either prompt insertion of tympanostomy tubes or delayed insertion if effusion persisted, as part of a randomized clinical trial or a separate observational cohort study. Prompt insertion of tympanostomy tubes did not improve developmental outcomes at 9 to 11 years of age — findings that were consistent with the results up to the age of 6 years. These findings provide additional support for a strategy of watchful waiting for children who have persistent middle-ear effusion.