It is well understood that cancer symptoms vary depending on the tumor's location and spread. However, there has been less focus on whether the prevalence of different cancer symptoms has changed over time. A 17-year study published in the British Journal of General Practice sought to fill this knowledge gap. Researchers aimed to identify the first reported symptoms of potential lung cancer and examine whether the percentages of patients experiencing each current symptom changed during the period from 2000 to 2017.
They extracted data from the Clinical Practice Research Datalink (CPRD) with linked data from the National Cancer Registration and Analysis Service (NCRAS). The CPRD is defined as a large database of encrypted and anonymized electronic medical records generated during daily consultations from over 600 general practices in the UK. Symptoms of patients diagnosed with lung cancer were identified in annual cohorts between January 1, 2000, and December 31, 2017.
The researchers noted that the percentage of patients presenting with breathlessness, also known as difficulty in breathing, "increased" over time. A similar upward trend was observed for coughing. Meanwhile, the percentages of patients exhibiting other symptoms, particularly hemoptysis, also known as coughing up blood, and loss of appetite, decreased. The researchers concluded that "between 2000 and 2017, the proportion of lung cancer patients with symptoms of coughing or breathlessness increased, while the proportion with symptoms of hemoptysis decreased." They added, "This trend has implications for medical education and awareness campaigns regarding the quality of symptoms."
This study is limited by its use of coding to determine whether a patient experienced symptoms. "Read codes" do not provide information about the duration or severity of symptoms, nor whether the symptoms were self-reported or inferred by the physician. Some patients may be misclassified if symptoms were not recorded in a retrievable part of the medical records. Symptoms described in free text are inaccessible. There is evidence that this may lead to biased estimates favoring fixed symptoms, such as hemoptysis, which are more likely to be recorded than "low-risk" symptoms that are not absent.
Moreover, a small number of patients presented with an unspecified primary care symptom with "suspected cancer" or abnormal chest X-ray codes, which could not be further classified. Changes in coding practices and the characteristics of general practices contributing data to the CPRD over time may alter estimates of recorded symptom prevalence. Encouragingly, the proportion of patients with any recorded symptoms remained relatively stable over time, indicating that none of these changes were significant.
