Does the false-negative rate for 1 or 2 negative sentinel nodes after neo-adjuvant chemotherapy translate into a high local recurrence rate?

Prospective trials demonstrate that sentinel node (SN) biopsy after neo-adjuvant chemotherapy (NACT) has a significant false-negative rate (FNR) when only 1 or 2 SNs are removed. It is unknown whether this increased FNR correlates with an elevated risk of recurrence. Tumor Registry data at an NCI-Designated Comprehensive Cancer Center were reviewed from 2004 to 2018 for patients having a negative SN biopsy after NACT. Among 190 patients with histologically negative nodes after NACT having 1 (n = 42), 2 (n = 46), and ≥3 (n = 102) SNs, axillary recurrences occurred in 7.14%, 0%, and 1.96% (p = 0.09), breast recurrences occurred in 2.38%, 6.52%, and 0.98% (p = 0.12), and distance recurrences occurred in 16.67%, 8.70%, and 7.84% (p = 0.27), respectively. Time to first recurrence did not differ by SN count (p = 0.41). After adjustment for age, race, clinical stage, and receptor status, there were no differences in the rates of axillary (p = 0.26), breast (p = 0.44), or distance recurrence (p = 0.24) by numbers of SNs harvested. Median follow-up was 46.8 months. Despite higher post-NACT FNRs reported in randomized trials for patients having <3 sentinel nodes, recurrence rates were not significantly different for 1 versus 2 versus ≥3 SNs. This suggests that patients having 1 or 2 post-NACT SNs identified may not necessitate axillary dissection.     

Firing properties of hippocampal neurons in a visually symmetrical environment: contributions of multiple sensory cues and mnemonic processes

The location-specific firing of hippocampal place cells can easily be brought under the control of experimenter-defined cues. Nevertheless, there is evidence that these firing fields are not determined just by immediate sensory input, but also by earlier states of the nervous system (O'Keefe and Speakman, 1987). Here, we report further on the roles of multiple visual cues and mnemonic processes in determining the firing of place cells. Rats were trained to chase food pellets in a cylinder with homogeneous gray walls and 1 white cue card. After a cell's field was recorded in this "standard" condition, probe sessions were conducted in which a second card was placed 180 degrees away from the first. This configuration created a diametrically symmetrical environment in which pairs of locations 180 degrees apart were identical with respect to views of the wall and cards. If place cells are strongly controlled by these immediately available views, firing in the 2-card configuration should be diametrically symmetrical. Alternatively, because the rat moves freely in the cylinder, information is available that pairs of visually identical places are not truly the same. If some mnemonic process stores and updates information about the rat's paths during the session, it is possible that the firing pattern will be different in 2 such places, especially because the original training was conducted in the 1-card, asymmetrical environment. Thirteen of 18 cells had a single, asymmetric firing pattern after the second card was introduced; the field was the same size and shape as in the 1-card configuration and in the same spatial relation to 1 of the 2 cards. The field position during 2-card sessions could be rotated 180 degrees by starting the rat by one card or the other. In further probe sessions in which the cue cards, entry location, and background cues were, in various combinations, rotated in relation to each other, these cells always showed a single field, similar in size and shape to that in the standard, and in the same relationship as in the standard to as many cues as possible. The remaining 5 cells showed complex changes over repeated 2-card sessions, and 3 of these showed paired fields, 180 degrees apart for at least some of the sessions. In one case, the second field disappeared with repeated exposures to 2 cards; in another, the second field persisted when only 1 card was used. We conclude that place cells are influenced both by the immediate sensory configuration and by internal neural states related to earlier experience in the environment.     

Commentary on health care reform and opportunities for dietitians

Health care in Canada is driven by global economic pressures. Financing solutions will be found through a national strategy for effective quality management of the health care delivery system. Achieving quality effectiveness will demand a new level of accountability and participation in planning from both users and providers. Restructuring and reform will support a shift from disease treatment and from traditional institutions to health promotion and primary care prevention in community based settings. Along with the shift in focus and delivery systems will be new opportunities for dietitians in new roles and in new settings. The specialized knowledge of dietitians, nourishing people under all life's circumstances, is highly valued by society. Now is not a time when dietitians can afford to be passive about our preferred role in the health system. This is a time to learn new skills and to move beyond the role boundaries of the past. This is a time to invest in research that leads to cost-effective, accountable practices.     

What can and should be done to reduce publication bias? The perspective of an editor

"Publication bias" has three facets: (1) bias perceived by disappointed authors, (2) bias that journal policy may introduce, and (3) bias intrinsic in design and interpretation of the work itself. The third type, though a target of peer review, is not considered here, and the first type is more often imagined than real. However, general journals have to adopt policies on priorities that an outsider may see as bias, in the broadest sense. Opportunities for bias exist (18 varieties are listed here), but more objective evaluation is required before journals need to alter their peer review practices. In terms of work load and financial considerations, the price of some proposed correctives is high. Journals should monitor refereeing systems and allow appeals, but the case for policing systems--"blinding" referees (and, logically, editors), introducing tight codes of practice, and seeking solemn declarations of integrity, for example--needs more hard evidence.     

Tutorial: chaos theory--a primer for health care

Chaos theory, also called nonlinear systems theory, provides new insights into processes previously thought to be unpredictable and random. It also provides a new set of tools that can be used to analyze common administrative and clinical data. This tutorial provides an introduction to chaos theory. Subsequent articles will address applications of those principles to the administrative activities of health care organizations, implications of those principles for clinical data, and application of chaos theory concepts to our understanding of organizational dynamics.     

The effect of encapsulated soluble fiber on carohydrate metabolism during exercise

Previous investigations have reported that soluble fiber reduces the plasma glucose and insulin changes after an oral glucose load. To improve the palatability of a soluble-fiber feeding, this study addressed how a combined, soluble fiber (delivered in capsule form) and a preexercise CHO feeding would affect metabolic responses during exercise. On 3 different days, participants ingested a placebo (CON), 75 g liquid CHO (GLU), or 75 g liquid CHO with 14.5 g encapsulated guar gum (FIB) 45 min before cycling for 60 min at 70% VO2 peak. Peak concentrations of plasma glucose and insulin were similar and significantly greater than CON preexercise (p < 05). Similarities in carbohydrate reliance were observed in GLU and FIB. Muscle glycogen use did not differ significantly among trials. These results demonstrate that encapsulated soluble fiber delivered with liquid CHO feeding does not affect plasma glucose, insulin, or muscle glycogen utilization during exercise.     

Initiation of cigarette smoking and subsequent smoking behavior among U.S. high school students

BACKGROUND: Most adult smokers report trying their first cigarette before age 18 years. Understanding the impact of smoking initiation at young ages may help public health policy makers and practitioners improve strategies to prevent or delay adolescent cigarette smoking. METHODS: This paper examined age of initiation of cigarette smoking and subsequent patterns of smoking among U.S. high school students 16 years of age and older (N = 13,858). We used data from the 1991-1997 national Youth Risk Behavior Surveys, conducted by the Centers for Disease Control and Prevention. RESULTS: The majority of students 16 years of age and older (60.4%) reported ever having smoked a whole cigarette, and 11.1% initiated smoking at age 10 years or younger. Age of smoking initiation was significantly related to current frequent smoking, daily smoking, and whether students had ever smoked daily. A younger age of smoking initiation was associated with smoking more cigarettes per day than was initiating at an older age. CONCLUSIONS: Delaying the onset of smoking may affect the likelihood of becoming addicted to nicotine and smoking heavily. For students who are already addicted to nicotine, smoking cessation programs are needed.     

Incidence of childhood brain and other non-haematopoietic neoplasms near nuclear sites in Scotland, 1975-94

OBJECTIVES: To examine the risk of cancers other than leukaemia and non- Hodgkin's lymphoma in children resident in the vicinity of nuclear sites in Scotland. METHODS: The study dataset comprised registrations of cancer other than leukaemia and non-Hodgkin's lymphoma diagnosed in children aged under 15 in the period 1975-94. These were validated for completeness and accuracy and analysed in two groups: (a) tumours of the central nervous system and (b) other malignant tumours (excluding leukaemia and non-Hodgkin's lymphoma). Around each nuclear site observed cases (O) were enumerated and expected numbers (E) calculated with adjustment for age, sex, deprivation, and an urban-rural category. Stone's maximum likelihood ratio test (MLR) was used to determine whether there was any evidence of increased risk of these neoplasms among children living within 25 km of one of the nuclear sites investigated. The significance level of each MLR statistic was estimated by simulation. RESULTS: More tumours of the central nervous system were observed than expected within 25 km of Dounreay (O/E = 1.14), Hunterston (1.14), and Rosyth (1.22). These results were based on 2, 26, and 136 observed cases, respectively. The unconditional MLR was significant only for Rosyth (p = 0.006). The conditional application of the MLR test for Rosyth was not significant (p = 0.771). For the group of other malignant neoplasms, the unconditional MLR test was not significant for any of the seven sites. CONCLUSIONS: There was no evidence for generally increased risk of either tumours of the central nervous system or other malignant tumours in children living near nuclear sites. The significant excess of tumours of the central nervous system around Rosyth is likely to be due to the high incidence of these tumours in east central Scotland. Further investigations in this area are warranted.