Mammographic Density Decline, Tamoxifen Response, and Prognosis by Molecular Characteristics of Estrogen Receptor-Positive Breast Cancer

Background: Mammographic breast density (MBD) decline post-tamoxifen initiation is a favorable prognostic factor in estrogen receptor (ER)-positive breast cancer (BC) and has potential utility as a biomarker of tamoxifen response. However, the prognostic value of MBD decline may vary by molecular characteristics among ER-positive patients. Methods: We investigated associations between MBD decline (≥10% vs <10%) and breast cancer-specific mortality (BCSM) among ER-positive breast cancer patients aged 36-87 years at diagnosis treated with tamoxifen at Kaiser Permanente Northwest (1990-2008). Patients who died of BC (case patients; n = 62) were compared with those who did not (control patients; n = 215) overall and by tumor molecular characteristics (immunohistochemistry [IHC]-based subtype [luminal A-like: ER-positive/progesterone receptor [PR]-positive/HER2-negative/low Ki67; luminal B-like: ER-positive and 1 or more of PR-negative, HER2-positive, high Ki67] and modified IHC [mIHC]-based recurrence score of ER/PR/Ki67). Percent MBD was measured in the unaffected breast at baseline mammogram (mean = 6 months before tamoxifen initiation) and follow-up (mean = 12 months post-tamoxifen initiation). Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were computed from logistic regression models. All statistical tests were 2-sided. Results: MBD decline was statistically significantly associated with reduced risk of BCSM overall (OR = 0.38, 95% CI = 0.15 to 0.92). This association was, however, stronger among women with aggressive tumor characteristics including luminal B-like (OR = 0.17, 95% CI = 0.04 to 0.73) vs A-like (OR = 0.74, 95% CI = 0.19 to 2.92); large (OR = 0.26, 95% CI = 0.08 to 0.78) vs small (OR = 0.41, 95% CI = 0.04 to 3.79) tumors; PR-negative (OR = 0.02, 95% CI = 0.001 to 0.37) vs PR-positive (OR = 0.50, 95% CI = 0.18 to 1.40) disease; and high (OR = 0.25, 95% CI = 0.07 to 0.93) vs low (OR = 0.44, 95% CI = 0.10 to 2.09) mIHC3 score. Conclusion: The findings support MBD decline as a prognostic marker of tamoxifen response among patients with aggressive ER-positive BC phenotypes, for whom understanding treatment effectiveness is critical

The IMF in Starbursts

The history of the IMF in starburst regions is reviewed. The IMFs are no longer believed to be top-heavy, although some superstar clusters, whether in starburst regions or not, could be. General observations of the IMF are discussed to put the starburst results in perspective. Observed IMF variations seem to suggest that the IMF varies a little with environment in the sense that denser and more massive clusters produce more massive stars, and perhaps more brown dwarfs too, compared to intermediate mass stars.Comment: 8 pages, to be published in ``Starbursts: from 30 Doradus to Lyman Break Galaxies,'' held at Institute of Astronomy, Cambridge University, UK, September 6-10, 2004. Kluwer Academic Publishers, edited by Richard de Grijs and Rosa M. Gonzalez Delgad

Cluster Density and the IMF

Observed variations in the IMF are reviewed with an emphasis on environmental density. The remote field IMF studied in the LMC by several authors is clearly steeper than most cluster IMFs, which have slopes close to the Salpeter value. Local field regions of star formation, like Taurus, may have relatively steep IMFs too. Very dense and massive clusters, like super star clusters, could have flatter IMFs, or inner-truncated IMFs. We propose that these variations are the result of three distinct processes during star formation that affect the mass function in different ways depending on mass range. At solar to intermediate stellar masses, gas processes involving thermal pressure and supersonic turbulence determine the basic scale for stellar mass, starting with the observed pre-stellar condensations, and they define the mass function from several tenths to several solar masses. Brown dwarfs require extraordinarily high pressures for fragmentation from the gas, and presumably form inside the pre-stellar condensations during mutual collisions, secondary fragmentations, or in disks. High mass stars form in excess of the numbers expected from pure turbulent fragmentation as pre-stellar condensations coalesce and accrete with an enhanced gravitational cross section. Variations in the interaction rate, interaction strength, and accretion rate among the primary fragments formed by turbulence lead to variations in the relative proportions of brown dwarfs, solar to intermediate mass stars, and high mass stars.Comment: 14 pages, 3 figures, to be published in ``IMF@50: A Fest-Colloquium in honor of Edwin E. Salpeter,'' held at Abbazia di Spineto, Siena, Italy, May 16-20, 2004. Kluwer Academic Publishers; edited by E. Corbelli, F. Palla, and H. Zinnecke

Physical Processes in Star Formation

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio

A revision of the higher taxonomy of the Afrotropical freshwater crabs (Decapoda: Brachyura) with a discussion of their biogeography

The higher taxonomy of the 20 known genera of Afrotropical freshwater crabs is revised to reflect the evolutionary relationships revealed by the consensus of a series of recent morphological and molecular phylogenetic studies of the group. The Afrotropical freshwater crab genera fall into two monophyletic groups, one from Socotra with two genera (Potamidae) and another that includes the remaining 18 genera. The latter group, which includes the bulk of the region's freshwater crab fauna, forms a well-supported monophyletic clade. We recognize two monophyletic sister groups (subfamilies) within the Potamonautidae, one for seven genera from Africa (the Potamonautinae) and one for 11 genera from Africa, the Seychelles, and Madagascar (the Deckeniinae). The Deckeniinae includes two monophyletic groups (tribes), one with seven genera from Madagascar (the Hydrothelphusini), and one with four genera from Africa and the Seychelles (the Deckeniini). The Deckeniini is further divided here into two subtribes, the Deckeniina and the Globonautina. The Platythelphusidae is not recognized, and the Deckeniidae and Globonautinae are lowered in rank. There is no phylogenetic support for the continued inclusion of any genus from the Afrotropical region in the Gecarcinucidae which is treated here as an exclusively Oriental family. The Afrotropical freshwater crabs (excluding those from Socotra) form a monophyletic assemblage that has no representatives outside of the region. The wider biogeographical implications of the taxonomic revision are discussed. © 2008 The Linnean Society of London.Articl