Cancer of unknown primary statistics


New cases of cancer of unknown primary, 2013, UK


Deaths from cancer of unknown primary, 2014, UK

  • There were around 9,300 new cases of cancer of unknown primary in the UK in 2013, that’s 25 cases diagnosed every day.
  • Cancer of unknown primary accounts for 3% of all new cases in the UK (2013).
  • In males, there were around 4,400 cases of cancer of unknown primary diagnosed in the UK in 2013.
  • In females, there were around 4,900 cases of cancer of unknown primary diagnosed in the UK in 2013.
  • Almost 6 in 10 (56%) cancer of unknown primary cases in the UK each year are diagnosed in people aged 75 and over (2011-2013).
  • Over the last decade, cancer of unknown primary incidence rates have decreased by more than a third (35%) in the UK. The decrease is slightly larger in males (38%, almost two-fifths) than in females (34%, around a third).
  • Most cancers of unknown primary occur in the respiratory and digestive organs.
  • 1 in 64 people will be diagnosed with cancer of unknown primary during their lifetime.
  • Cancer of unknown primary in England is more common in people living in the most deprived areas.

See more in-depth cancer of unknown primary incidence statistics

  • There were around 10,100 cancer of unknown primary (CUP) deaths in the UK in 2014, that’s 28 deaths every day.
  • CUP accounts for 6% of all cancer deaths in the UK (2014).
  • In males in the UK, there were around 4,900 CUP deaths in 2014.
  • In females in the UK, there were around 5,300 CUP deaths in 2014.
  • More than 4 in 10 (44%) cancer of unknown primary deaths in the UK each year are in people aged 80 and over (2012-2014).
  • Mortality rates for cancer of unknown primary in the UK are highest in people aged 90+ (2012-2014).
  • Since the mid 1990s, cancer of unknown primary (CUP) mortality rates have decreased by more than two-fifths (42% decrease) in the UK. The decrease is larger in males (48%), than in females (37%).
  • In the last decade, CUP mortality rates have decreased by almost a third (31%) in the UK. The decrease is similar in males (33%) and females (30%).
  • Cancer of unknown primary deaths in England are more common in females living in the most deprived areas.

See more in-depth cancer of unknown primary mortality statistics

  • Almost 9 in 10 patients had a ‘very good’ or ‘excellent’ patient experience.
  • Around 8 in 10 patients are given the name of their Clinical Nurse Specialist.

See more in-depth cancer of unknown primary diagnosis and treatment statistics

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The latest statistics available for cancer of unknown primary in the UK are; incidence 2013 and mortality 2014. Reliable survival data for the UK is currently not available.

The ICD codes Open a glossary item for cancer of unknown primary are ICD-10 C77-C80 (which include secondary and unspecified malignant neoplasm of lymph nodes, secondary malignant neoplasm of respiratory and digestive organs, secondary malignant neoplasm of other sites, and malignant neoplasm without specification of site).

European Age-Standardised Rates were calculated using the 1976 European Standard Population (ESP) unless otherwise stated as calculated with ESP2013. ASRs calculated with ESP2013 are not comparable with ASRs calculated with ESP1976.

Lifetime risk estimates were calculated using incidence, mortality, population and all-cause mortality data for 2012.

Cancer of unknown primary (CUP) is an inexact term, making it hard to represent accurately. Patients are recorded as having CUP if the primary site of the malignancy cannot be established or the tumour has been registered without specification of site. Capturing and reporting the incidence of CUP cases can be difficult. In some patients the primary site or the tumour type cannot be determined, even after extensive investigations. In others, patients presenting with wide-spread metastases without an obvious primary site may be too ill to undergo invasive tests or have cancer at such an advanced stage that further investigations would no longer aid their diagnosis or treatment. Both scenarios will lead to patients being registered as CUP. However, some patients, initially diagnosed with CUP, may subsequently have their primary site determined (either during the diagnostic/treatment process or at post-mortem) and will thus no longer be registered and counted as CUP. Finally, a few cases may be misclassified and end up registered as CUP when the clinical or pathological information transmitted to the Cancer Registry is insufficient; for example if the primary site of the malignancy is not indicated on the notes or reports. Due to this unspecific classification the National Institute for Health and Clinical Excellence (NICE) issued a guideline which stated that the majority of CUP can be covered by the ICD codes ICD-10 C77-C801, so the statistics presented on these pages are our best current understanding of the incidence of CUP.

Mortality statistics for CUP are further complicated by the fact that they are compiled separately from cancer registration, at the Office for National Statistics (ONS), and are based solely on the clinical statement of causes of death on the death certificate. Depending on circumstances the clinician completing the death certificate may not be aware of, or have access to, the deceased patient's primary cancer diagnosis or might only state the metastatic spread of the cancer as the cause of death. As ONS have to rely on the death certificate this can lead to higher mortality statistics for more vague ICD-10 codes, which includes the metastatic and unknown primary codes defined as CUP. Thus, CUP mortality figures are, in part, thought to be higher than CUP incidence figures because a cause of death statement of, for example, 'cancer' or 'metastatic liver disease' would result in a CUP mortality code even if the patient was not originally diagnosed with CUP.

Patient Experience data is for adult patients in England with a primary diagnosis of cancer, who were in active treatment between September and November 2013 and who completed a survey in 2014.

Deprivation gradient statistics were calculated using incidence data for three time periods: 1996-2000, 2001-2005 and 2006-2010 and for mortality for two time periods: 2002-2006 and 2007-2011. The 1997-2001 mortality data were only used for the all cancers combined group as this time period includes the change in coding from ICD-9 to ICD-10. The deprivation quintiles were calculated using the Income domain scores from the Index of Multiple Deprivation (IMD) from the following years: 2004, 2007 and 2010. Full details on the data and methodology can be found in the Cancer by Deprivation in England NCIN report.


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We would like to acknowledge the essential work of the cancer registries in the United Kingdom and Ireland Association of Cancer Registries, without which there would be no data.

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