Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer (EORTC 10981-22023 AMAROS): a randomised, multicentre, open-label, phase 3 non-inferiority trial.

BACKGROUND: If treatment of the axilla is indicated in patients with breast cancer who have a positive sentinel node, axillary lymph node dissection is the present standard. Although axillary lymph node dissection provides excellent regional control, it is associated with harmful side-effects. We aimed to assess whether axillary radiotherapy provides comparable regional control with fewer side-effects. METHODS: Patients with T1-2 primary breast cancer and no palpable lymphadenopathy were enrolled in the randomised, multicentre, open-label, phase 3 non-inferiority EORTC 10981-22023 AMAROS trial. Patients were randomly assigned (1:1) by a computer-generated allocation schedule to receive either axillary lymph node dissection or axillary radiotherapy in case of a positive sentinel node, stratified by institution. The primary endpoint was non-inferiority of 5-year axillary recurrence, considered to be not more than 4% for the axillary radiotherapy group compared with an expected 2% in the axillary lymph node dissection group. Analyses were by intention to treat and per protocol. The AMAROS trial is registered with ClinicalTrials.gov, number NCT00014612. FINDINGS: Between Feb 19, 2001, and April 29, 2010, 4823 patients were enrolled at 34 centres from nine European countries, of whom 4806 were eligible for randomisation. 2402 patients were randomly assigned to receive axillary lymph node dissection and 2404 to receive axillary radiotherapy. Of the 1425 patients with a positive sentinel node, 744 had been randomly assigned to axillary lymph node dissection and 681 to axillary radiotherapy; these patients constituted the intention-to-treat population. Median follow-up was 6·1 years (IQR 4·1-8·0) for the patients with positive sentinel lymph nodes. In the axillary lymph node dissection group, 220 (33%) of 672 patients who underwent axillary lymph node dissection had additional positive nodes. Axillary recurrence occurred in four of 744 patients in the axillary lymph node dissection group and seven of 681 in the axillary radiotherapy group. 5-year axillary recurrence was 0·43% (95% CI 0·00-0·92) after axillary lymph node dissection versus 1·19% (0·31-2·08) after axillary radiotherapy. The planned non-inferiority test was underpowered because of the low number of events. The one-sided 95% CI for the underpowered non-inferiority test on the hazard ratio was 0·00-5·27, with a non-inferiority margin of 2. Lymphoedema in the ipsilateral arm was noted significantly more often after axillary lymph node dissection than after axillary radiotherapy at 1 year, 3 years, and 5 years. INTERPRETATION: Axillary lymph node dissection and axillary radiotherapy after a positive sentinel node provide excellent and comparable axillary control for patients with T1-2 primary breast cancer and no palpable lymphadenopathy. Axillary radiotherapy results in significantly less morbidity. FUNDING: EORTC Charitable Trust.

Catalase negative Staphylococcus aureus retain virulence in mouse model of chronic granulomatous disease.

Myeloperoxidase-mediated chlorination is thought to be a necessary microbicidal mechanism. The H2O2 required for this process is generated by the NADPH oxidase. Staphylococcus aureus can also produce H2O2, which is not broken down by catalase negative organisms. It has been thought that this bacterial H2O2 can substitute for cellular H2O2 in the halogenation reaction in chronic granulomatous disease (CGD) where neutrophils are lacking the NADPH oxidase. We have readdressed this issue in a mouse model of CGD using clinical isolates of catalase positive and negative strains of S. aureus. The results showed these organisms to be equally virulent and that the H2O2 they produced is insufficient to cause significant iodination, a marker for chlorination, thereby contradicting the accepted views on this subject.

CD95 death-inducing signaling complex formation and internalization occur in lipid rafts of type I and type II cells.

We investigated the membrane localization of CD95 in type I and type II cells, which differ in their ability to recruit and activate caspase-8. We found that CD95 was preferentially located in lipid rafts of type I cells, while it was present both in raft and non-raft plasma membrane sub-domains of type II cells. After stimulation, CD95 located in phospholipid-rich plasma membrane was recruited to lipid rafts in both types of cells. Similarly, CD95 cross-linking resulted in caspase-independent translocation of FADD/MORT1 and caspase-8 to the lipid rafts, which was prevented by a death domain-defective receptor. CD95 internalization was then rapid in type I and delayed in type II cells and showed a substantial correlation with the kinetics of Fas-associated death domain (FADD)and caspase-8 recruitment to lipid rafts. Finally, electron microscopy analysis showed that after CD95 stimulation lipid rafts aggregated in large clusters that were internalized in endosomal vesicles, where caspase-8 underwent massive processing. Taken together, our data demonstrate that CD95 death-inducing signaling complex formation and internalization in type I and type II cells occur in lipid rafts, which are a major site of caspase-8 activation.

Killing activity of neutrophils is mediated through activation of proteases by K+ flux.

According to the hitherto accepted view, neutrophils kill ingested microorganisms by subjecting them to high concentrations of highly toxic reactive oxygen species (ROS) and bringing about myeloperoxidase-catalysed halogenation. We show here that this simple scheme, which for many years has served as a satisfactory working hypothesis, is inadequate. We find that mice made deficient in neutrophil-granule proteases but normal in respect of superoxide production and iodinating capacity, are unable to resist staphylococcal and candidal infections. We also show that activation provokes the influx of an enormous concentration of ROS into the endocytic vacuole. The resulting accumulation of anionic charge is compensated for by a surge of K+ ions that cross the membrane in a pH-dependent manner. The consequent rise in ionic strength engenders the release of cationic granule proteins, including elastase and cathepsin G, from the anionic sulphated proteoglycan matrix. We show that it is the proteases, thus activated, that are primarily responsible for the destruction of the bacteria.