Malignant pleural effusion can occur in up to half of the patients with metastatic disease. It can cause shortness of breath to patients and so far there is no protocol on its management.

The study is looking at patients with malignant pleural effusion and aims to identify its prognostic factors.

Pleural fluid and blood analysis will be performed as in the standard of care and results will be collected at the start of diagnosis. This will not affect subsequent management plan. Patients' disease course will be followed up and progress data will be collected. Data will then be analysed to identify relevant prognostic factors.

Malignant pleural effusion (MPE) is common, and is estimated to affect up to a half of patients with malignancy, either at the time or during subsequent clinical course after the diagnosis of malignancy. Lung cancer is the most common cause of MPE, followed by breast cancer, lymphoma, unknown primary genitourinary and gastrointestinal carcinoma. Pleural involvement indicates dissemination of malignancy and suggests a poorer prognosis and the median survival rate ranges from 3 to 12 months, with lung cancer showing the shortest survival among Caucasian cohorts. Patients with MPE frequently suffer from effusion related symptoms requiring therapeutic drainage. Conventionally, the options of therapeutic drainage of MPE include needle aspiration, and intercostal drain insertion with or without chemical pleurodesis. Needle aspiration allows quick relief of effusion and symptoms, though the volume of pleural effusion being aspirated with each attempt of needle puncture is limited to 1-1.5 litres, and repeated puncture involves risks of complications. Intercostal drain insertion will allow gradual drainage of large pleural effusion over days, but the shortcomings being the long hospitalization of at least a week, and the presence of trapped lung would preclude chemical pleurodesis for definitive fluid control. Up to 40% of MPE patients still require repeated pleural drainage procedure, even after Talc chemical pleurodesis. The much longer hospitalization period is considered unfavourable for patients with limited lifespan in terms of weeks or a few months, who would spend more time with their family. In recent few years, indwelling pleural catheter (IPC) has provided a relatively novel option of palliative MPE drainage, on an ambulatory out-patient setting. IPC has been reported to be cost-effective, in particular for patients with survival of less than 14 weeks. With the limited time span, it is important to balance between the aim of symptomatic relief and maintaining patient's quality of life. Invasive procedures and prolonged hospitalisation can cause great distress to patients. Predicted survival of patients with MPE would be important in informing the most suitable method for relieving MPE. Previous studies have identified relevant factors on prediction of survival in patients with malignant pleural effusion but so far, there is no data for Chinese patients. The LENT scoring system (pleural fluid lactate dehydrogenase, Eastern Cooperative Oncology Group performance score, neutrophil -to-lymphocyte ratio and tumour type) is a new validated prognostic score in malignant pleural effusion.

Inclusion Criteria:

• malignant pleural effusion (MPE) due to lung cancer

Exclusion Criteria:

• workup of MPE (pleural fluid results, blood test results, or treatment history) not available
• Patients unwilling to join study (for prospective recruitment)

Retrospective retrieval of list of subjects diagnosed to have malignant pleural effusion (MPE). Subjects diagnosed to have MPE who are under the care of Department of Medicine in Queen Mary Hospital, Hong Kong, will be invited to participate in the study