S-phase fraction as an independent prognostic factor of long-term overall survival in patients with early-stage or locally advanced invasive breast carcinoma.

BACKGROUND: Large retrospective archival studies of S-phase fraction (SPF) measured by DNA flow cytometry in patients with breast carcinoma have shown its long-term prognostic relevance. However, contradictory results have also been reported, some of them being related to the various methods of SPF calculation using different commercially available software. METHODS: DNA flow cytometric list mode data, initially computed with Cellfit software, were blindly reanalyzed using Modfit and Multicycle software. The data, acquired prospectively between 1990 and 2003 from cytologic fine-needle aspiration biopsy samples of 397 patients with breast carcinoma, were compared with patient outcome with a median follow-up of 99 months (8.2 yrs). RESULTS: Measurement of SPF was successful in 321 (81.7%), 362 (92.1%), and 335 cases (85.2%) by means of the Cellfit, Modfit, and Multicycle software programs, respectively. In 306 cases (77.9%), SPF values were obtained using all 3 methods. Comparisons between SPF measurements showed a good agreement between Modfit and Multicycle computations. In the series of 306 patients, SPF median values of 2.5%, 4.3%, and 5.45% for Cellfit, Modfit, and Multicycle, respectively, were also found to be statistically different. Regardless of the software used, high SPF defined as above the median value was an independent factor of prognosis in a multivariate analysis including all traditional clinicopathologic parameters. It is noteworthy that this was also observed in the subgroups of patients either treated by primary surgery for an early tumor (n = 133) or by neoadjuvant chemotherapy for a locally advanced breast carcinoma (n = 173). CONCLUSIONS: The data in the current study supported the prognostic relevance of SPF measurement in predicting the long-term overall survival of patients with early-stage or locally advanced invasive breast carcinoma.

Effects of intrapartum penicillin prophylaxis on intestinal bacterial colonization in infants.

Early-onset group B streptococcal (GBS) infections remain a leading cause of morbidity and mortality in infants. To prevent the vertical transmission of GBS and neonatal GBS infection, guidelines recommend intrapartum penicillin or amoxicillin prophylaxis. This intrapartum antibiotic prophylaxis (IAP) is suspected to favor colonization by antibiotic-resistant bacteria. However, the effects of this prophylaxis on the patterns of acquisition of gastrointestinal bacterial flora in infants have never been studied. We collected stool samples from 3-day-old infants born to mothers who received intrapartum amoxicillin (antibiotic-exposed group; n = 25) and to untreated mothers (non-antibiotic-exposed group; n = 25). The groups were matched for factors known to affect intestinal microbial colonization: gestational age, type of delivery, and type of feeding. Qualitative and quantitative differential analyses of the bacterial flora in stool samples were performed. Similar numbers of infants in the non-antibiotic-exposed and antibiotic-exposed groups were colonized by aerobic bacteria and amoxicillin-resistant enterobacteria (75 and 77%, respectively) (P = 0.79). In contrast, significantly fewer infants in the antibiotic-exposed group than in the non-antibiotic-exposed group were colonized by anaerobic bacteria, especially Clostridium (12 and 40%, respectively) (P < 0.05). Regarding intestinal bacterial colonization, the differences between antibiotic-exposed and non-antibiotic-exposed infants were remarkably few. The only statistically significant effect was the reduced initial bacterial colonization by Clostridium in the antibiotic-exposed group. In our study, the use of IAP did not favor colonization by beta-lactam-resistant bacteria. However, further evaluations are required to highlight the potential risks of the widespread use of antibiotics to prevent early-onset GBS infection.