weight loss and cancer risk

Last edited 11/2021 and last reviewed 11/2021

Weight loss is a non-specific symptom posing a diagnostic challenge to clinicians in non-specialist settings such as primary care

• can be associated with several cancer and non-cancer conditions (1)
  • two main diagnostic groupings exist:
  • patients with additional clinical features, such as haemoptysis, which can focus diagnostic efforts; and
  • patients without such a pointer in whom, if cancer is suspected, the clinician must consider several possible sites (2)

Re: weight loss and cancer

• people who have lost more weight are more likely to have cancer than those who have lost less (1)
• weight loss has been previously considered as a feature of advanced cancer only - however evidence relating to weight loss and cancer state diagnosis is conflicting:
  • studies of colorectal, pancreatic, and lung cancer have reported that even people with early-stage cancer may present with weight loss (3,4,5)
  • however, there is data that shows no relationship between weight loss and stage or mortality from colorectal cancer (6)
• weight loss might occur in the period immediately before a diagnosis is established, or be a symptom that occurs well before cancer is manifest

A systematic review was undertaken relating to weight loss and cancer risk (7):

• total of 25 studies were included, with 23 (92%) using primary care records
• of these, 20 (80%) defined weight loss as a physician’s coding of the symptom; the remainder collected data directly
• one defined unexplained weight loss using objective measurements
• positive associations between weight loss and cancer were found for 10 cancer sites:
• prostate, colorectal, lung, gastro-oesophageal, pancreatic, non-Hodgkin’s lymphoma, ovarian, myeloma, renal tract, and biliary tree
• sensitivity ranged from 2% to 47%, and specificity from 92% to 99%, across cancer sites
• positive predictive value for cancer in male and female patients with weight loss for all age groups >= 60 years exceeded the 3% risk threshold that current UK guidance proposes for further investigation
• risk with weight loss increases when it presents alongside another clinical feature suggesting an individual cancer site, and with increasing age

The study authors concluded that a primary care clinician's decision to code for weight loss is highly predictive of cancer. For such patients, urgent referral pathways are justified to investigate for cancer across multiple sites.

Reference:

• Wong CJ. Involuntary weight loss. Med Clin North Am 2014; 98(3): 625–643.
• Hamilton W. Five misconceptions in cancer diagnosis. BJGP 2009 DOI: https://doi.org/10.3399/bjgp09X420860.
• Olson SH, Xu Y, Herzog K, et al. Weight loss, diabetes, fatigue, and depression preceding pancreatic cancer. Pancreas 2016; 45(7): 986–991.
  Ewing M, Naredi P, Zhang C, Månsson J. Identification of patients with non-metastatic colorectal cancer in primary care: a case-control study. Br J Gen Pract 2016; DOI: https://doi.org/10.3399/bjgp16X687985
• Ades AE, Biswas M, Welton NJ, Hamilton W. Symptom lead time distribution in lung cancer: natural history and prospects for early diagnosis. Int J Epidemiol 2014; 43(6): 1865–1873.
• Stapley S, Peters TJ, Sharp D, Hamilton W. The mortality of colorectal cancer in relation to the initial symptom at presentation to primary care and to the duration of symptoms: a cohort study using medical records. Br J Cancer 2006; 95(10): 1321–1325.
• Nicholson BD et al. Weight loss as a predictor of cancer in primary care: a systematic review and meta-analysis. BJGP 2018; 68 (670): e311-e322. DOI: https://doi.org/10.3399/bjgp18X695801