Prognostic factors and hazard ratios in colorectal cancer patients over 80 years of age: a retrospective, 20-year, single institution review.

BACKGROUND: An aging population and a high incidence of colorectal cancer (CRC) in patients over the age of 80 make it important to understand survival times, hazard ratios and prognostic factors in this group. A better understanding of these factors will help clinicians determine appropriate therapeutic strategies for such patients, including when more aggressive treatment strategies may be preferred to palliative treatment. METHODS: A retrospective analysis of 619 CRC patients of ≥80 years of age from 1991-2010 at Baylor Scott & White Hospital in Temple, Texas. Twelve variables were analyzed through statistical analysis as potential prognostic factors for survival. Univariate and multivariate Cox proportional hazard models were used to determine hazard ratios. The elderly population was further stratified by age subgroup (80-84, 85-89, ≥90). RESULTS: Median survival time was 53.6, 30.0, and 11.3 months for age groups of 80-84, 85-89, and ≥90, respectively. Median survival time for stage 0/I, II, III, and IV patients was 72.4, 53.5, 28.0, and 5.9 months, respectively. Patients not receiving surgery had significantly higher mortality (hazard ratio 2.605; 95% CI, 1.826-3.694). For stage III CRC patients, those not receiving chemotherapy had significantly higher mortality (hazard ratio 1.808; 95% CI, 1.018-1.827). CONCLUSIONS: Our study provides evidence to support the benefits of surgery and chemotherapy (for stage III) patients over 80, potentially contributing to improved clinical decisions in treating elderly CRC patients. Such patients are sometimes undertreated due to their underrepresentation in clinical trials. Additional prospective studies with a higher proportion of patients over 80 are needed.

Controlled release of biologically active silver from nanosilver surfaces.

Major pathways in the antibacterial activity and eukaryotic toxicity of nanosilver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nanosilver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nanosilver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nanosilver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nanosilver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over 4 orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by preoxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and releasing inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through a bacterial inhibition zone assay carried out on selected formulations of controlled release nanosilver.