When unexpected weight loss warrants cancer investigation, finds BMJ study

The risk of undiagnosed cancer in adults attending primary care with unexpected weight loss( WL) alone is below the UK's current 3% threshold warranting investigation, a study suggests. According to the researchers, in male ever smokers aged 50 years or older and in all patients with other clinical features that could indicate cancer, the risk of undiagnosed cancer across multiple sites rises above the 3% threshold.

The researchers suggested that following symptoms or findings were associated with a cancer probability above 3% when they occurred along with weight loss:

In men and women: abdominal mass or pain, chest signs, iron-deficiency anemia, jaundice, loss of appetite, lymphadenopathy, low albumin levels, and elevated white cell counts, calcium, platelets, and inflammatory markers

In men: dysphagia, hemoptysis, and noncardiac chest pain

In women: back pain, bowel habit changes, dyspepsia, and venous thromboembolism

The study reports have recently been published in the British Medical Journal.

Brian D Nicholson et. al., at the Nuffield Department of Primary Care Health Sciences, University of Oxford, carried out the study with the purpose to quantify the predictive value of unexpected weight loss (WL) for cancer according to patient's age, sex, smoking status, and concurrent clinical features (symptoms, signs, and abnormal blood test results).

The study population consisted of 63, 973 adults (≥18 years) with a code for unexpected WL from 1 January 2000 to 31 December 2012. Using U.K. primary care records, researchers identified the adults with unexpected weight loss (mean loss of 5% or more in 6 months) for 12 years.

The results revealed the following facts.

• Of 63 973 adults with unexpected WL, 37 215 (58.2%) were women, 33 167 (51.8%) were aged 60 years or older, and 16 793 (26.3%) were ever smokers. 908 (1.4%) had a diagnosis of cancer within six months of the index date, of whom 882 (97.1%) were aged 50 years or older. Lung cancer was most common (24% of diagnoses), followed by colorectal, gastroesophageal, and pancreatic cancers.
• The positive predictive value for cancer was above the 3% threshold recommended by the National Institute for Health and Care Excellence for urgent investigation in male ever smokers aged 50 years or older, but not in women at any age.
• 10 additional clinical features were associated with cancer in men with unexpected WL, and 11 in women. Positive likelihood ratios in men ranged from 1.86 for non-cardiac chest pain to 6.10 for abdominal mass, and in women from 1.62 for back pain to 20.9 for jaundice.
• Abnormal blood test results associated with cancer included low albumin levels (4.67, 4.14 to 5.27) and raised values for platelets (4.57, 3.88 to 5.38), calcium (4.28, 3.05 to 6.02), total white cell count (3.76, 3.30 to 4.28), and C reactive protein (3.59, 3.31 to 3.89). However, no normal blood test results in isolation ruled out cancer.
• Clinical features co-occurring with unexpected WL were associated with multiple cancer sites.

The authors concluded that the risk of cancer in adults with unexpected WL presenting to primary care is 2% or less and does not merit investigation under current UK guidelines. However, in male ever smokers aged 50 years or older and in patients with concurrent clinical features, the risk of cancer warrants referral for invasive investigation.

For the full article click on the link: https://doi.org/10.1136/bmj.m2651

Primary source: British Medical Journal