Journals watch: Salt intake, obesity and prostate cancer

Too busy to read all of the journals? Dr Raj Thakkar selects the latest papers of interest to GPs including salt intake and cardiovascular mortality rates, obesity and cancer risk, prostate cancer, thrombolysis in acute stroke and alcohol and cardiovascular risk

Salt intake and cardiovascular mortality rates

N Engl J Med 2014; 371: 624-34

High sodium intake increases BP, a risk factor for cardiovascular disease (CVD), but the effects of sodium intake on cardiovascular mortality across the world are uncertain.

This meta-analysis, covering 66 countries, assessed the impact of dietary intake and urinary excretion of sodium on BP and CVD. Average salt intake varied from 2.18g to 5.51g per day, depending on the country, with a mean of 3.95g per day.

The researchers concluded that 1.65m cardiovascular deaths per year are attributable to excess sodium consumption (>2g per day) across the world. Almost two-thirds of these were in men and lower socioeconomic classes were over-represented. GPs should educate patients on the dangers of excessive salt intake.

Obesity and cancer risk

Lancet 2014; doi:10.1016/S0140-6736(14)60892-8

Obesity is a huge public health threat. Breast cancer risk, for example, is almost 10-fold in patients with a BMI of >30.

This population-based appraisal reviewed more than 5m UK adults for correlates between BMI and 22 site-specific tumours.

Nearly 170,000 cancers were investigated and common confounders were accounted for.

High BMI was found to be related to 17 of the 22 cancer types, but to varying degrees.

There was a linear relationship between each 5kg/m2 increase in BMI and uterine, cervical, gall bladder, renal and thyroid cancers, and leukaemia.

There was also a correlation with tumours of the liver, colon, ovary and breast (postmenopausal), although other factors made the relationship with BMI more complicated.

The researchers concluded that a population increase in BMI of just 1kg/m2 would increase the number of people diagnosed with cancer by 3,790 in one year alone.

Screening for prostate cancer

Lancet 2014; doi:10.1016/S0140-6736(14)60525-0

A significant number of patients have asymptomatic prostate cancer. This, combined with its high incidence, can make it difficult to refuse to refer a man for a PSA test.

The European Randomized Study of Screening for Prostate Cancer (ERSPC) has so far demonstrated a reduction in cancer mortality, but concerns have been expressed about overdiagnosis.

This paper, an update from the ERSPC data, aimed to eliminate selection bias to take into account those who chose not to participate in the study.

At 13 years of follow-up, 7,408 cases of prostate cancer were diagnosed in the screening arm, compared with 6,107 in the control cohort.

An argument may be made that those in the intervention arm had more aggressive disease, but screening showed a significant mortality reduction of 0.73 at 13 years if adjusting for non-participation.

With screening, one cancer death could be prevented for every 781 men invited for screening. Further work is needed, but this study is a step closer towards a national screening programme.

Thrombolysis in acute stroke

Lancet 2014; doi:10.1016/S0140-6736(14)60584-5

This meta-analysis looking at the risks of alteplase as a treatment for acute ischaemic stroke included 6,756 patients. Several outcome measures were considered.

It was clear that early treatment (within three hours) produced the best outcomes compared with placebo across all ages, irrespective of stroke severity.

The risk of fatal intracranial haemorrhage with alteplase was unaffected by age or stroke to needle time, but stroke severity was a factor.

At three to six months post-event, there was an excess of disability-free patients in the treatment arm. The authors advocate use of alteplase up to 4.5 hours post-event.

Alcohol and cardiovascular risk

Mayo Clin Proc 2014; pii: S0025-6196(14)00515-1. doi: 10.1016/j.mayocp.2014.05.014

This meta-analysis reviewed 11 studies to understand risk from alcohol in hypertensive patients.

All-cause mortality and cardiovascular risk compared with zero/occasional drinkers was 0.72 for those who drank 10g per day, 0.81 for those who drank 20g per day and 0.6 for those who drank 30g per day.

While these factors show some protective elements to alcohol consumption, it is important to consider the risk in its entirety on a case-by-case basis and to include personal commitments, social factors and other risk factors.

Reflect on this article and add notes to your CPD Organiser on MIMS Learning

  • Dr Thakkar is a GP in Wooburn Green, Buckinghamshire, and a member of our team who regularly review the journals

These further action points may allow you to earn more credits by increasing the time spent and the impact achieved.

  • Launch a disease prevention initiative in your practice to promote awareness of the risks of high salt diets and obesity.
  • Invite a local urologist to talk about the nuances of prostate cancer diagnosis.
  • Visit the hyperacute stroke unit and learn about how it works.

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