Level 2 Observational Studies: A Practical Alternative to Randomized Trials in Plastic Surgery

A novel risk factor for malignancy: Albuminuria

Cancer is the second leading cause of death among the adult population following cardiovascular diseases. Prevention and earlier diagnosis are among the cornerstones in the management of malignancies. Albuminuria is a diagnostic criterion for chronic kidney disease and has been associated with multiple conditions including cardiovascular diseases and systemic inflammation while the association between albuminuria and malignancy has been inadequately addressed. Large-scale observational studies with long follow-up periods demonstrate a statistically significant association between albuminuria and overall malignancy incidence, especially urothelial malignancy incidence. However, the underlying pathophysiology linking these two entities is not a straightforward causal relationship but most likely a multidirectional relationship including a causal link. In this narrative review, we evaluate the clinical studies investigating the association between albuminuria and malignancy along with potential underlying mechanisms linking them. We also summarize data on the impact of treatment modalities prescribed for albuminuria and/or proteinuria on the prevention or prognosis of malignancies.

Renin-angiotensin system blockade for the risk of cancer and death

INTRODUCTION

The effects of renin-angiotensin system blockade with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor blockers (ARBs) on cancer remain inconsistent.

METHODS

We searched existing databases from 1960 to August 2015, for randomised controlled trials and observational studies (case-control studies and cohort studies) of ARB/ACEI therapy with a minimal one year of follow-up. Outcomes were incidence and mortality of cancer.

RESULTS

We included 14 randomised controlled trials and 17 observational studies of 3,957,725 participants (350,329 ARB/ACEI users). The users had a lower incidence of cancer in the observational studies (RR 0.82, 95% CI 0.73-0.93) but not in the randomised controlled trials (RR 1.00, 95% CI 0.92-1.08). The protection persisted for lung cancer (RR 0.85, 95% CI 0.75-0.97) but not for other sites of cancer. The relative risk of cancer associated with renin-angiotensin system blockade was reduced along with time of follow-up. Mortality reduction with ARB/ACEI was marginally significant in the observational studies (RR 0.71, 95% CI 0.55-0.93) but not in the randomised controlled trials (RR 0.99, 95% CI 0.89-1.09).

CONCLUSIONS

The significant benefits of renin-angiotensin system blockade observed in case-control studies and cohort studies might diminish in randomised controlled trials. Clinical design, site of cancer and duration of follow-up may affect the clinical outcomes.