Southern ocean carbon and heat impact on climate

The Southern Ocean greatly contributes to the regulation of the global climate by controlling important heat and carbon exchanges between the atmosphere and the ocean. Rates of climate change on decadal timescales are therefore impacted by oceanic processes taking place in the Southern Ocean, yet too little is known about these processes. Limitations come both from the lack of observations in this extreme environment and its inherent sensitivity to intermittent processes at scales that are not well captured in current Earth system models. The Southern Ocean Carbon and Heat Impact on Climate programme was launched to address this knowledge gap, with the overall objective to understand and quantify variability of heat and carbon budgets in the Southern Ocean through an investigation of the key physical processes controlling exchanges between the atmosphere, ocean and sea ice using a combination of observational and modelling approaches. Here, we provide a brief overview of the programme, as well as a summary of some of the scientific progress achieved during its first half. Advances range from new evidence of the importance of specific processes in Southern Ocean ventilation rate (e.g. storm-induced turbulence, sea-ice meltwater fronts, wind-induced gyre circulation, dense shelf water formation and abyssal mixing) to refined descriptions of the physical changes currently ongoing in the Southern Ocean and of their link with global climate. This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.

Applying the QUARTZ Trial Results in Clinical Practice: Development of a Prognostic Model Predicting Poor Outcomes for Non-small Cell Lung Cancers with Brain Metastases

AIMS

The role of whole brain radiotherapy (WBRT) in patients with brain metastases from non-small cell lung cancers (NSCLC) has been questioned. However, no reliable criteria exist to identify patients who do not benefit from WBRT. The objective of the current study was to develop a prognostic model to identify such patients whose survival matches that of the Quality of Life after Treatment for Brain Metastases (QUARTZ) study.

MATERIALS AND METHODS

Outcome data of patients with NSCLC with brain metastases undergoing WBRT enrolled in a prospective observational study in a tertiary cancer centre were used to develop a prognostic model. Baseline clinico-radiological factors were used for development of the model. The model was internally validated and calibration accuracy was checked for prediction of 70 day mortality. The generated prognostic model was presented as a nomogram.

RESULTS

The median overall survival of 140 patients enrolled in the study was 166 days (95% confidence interval 108-242 days). The prognostic model identified gender, Karnofsky performance status and epidermal growth factor receptor activating mutation status as significant factors influencing overall survival. The model showed a modest discriminative ability with an optimism-corrected C-index of 0.64. However, model calibration error did reveal a moderate degree of calibration error. The high-risk subgroup identified by the model had a median overall survival of 67 days (95% confidence interval 56-101 days), which was similar to that observed in the QUARTZ trial.

CONCLUSION

This prognostic model derived from traditional clinico-radiological features had a modest ability to identify patients with poor prognosis who may not benefit from WBRT. However, the high-risk subgroup identified using this prognostic model had a survival similar to that observed for patients in the QUARTZ trial.