Certain diseases are more prevalent in communities due to multifactorial risks, some inherited and some acquired, during an individuals life-time.Each persons overall risk is individualized and unique. They are usually asymptomatic. Certain cancers like colon, stomach, oesophageal and breast cancers etc., are screened according to established guidelines.
Screening can be done using a clinical assessment, endoscopic procedures, radiological investigations, tumour markers (blood test) and genetic markers. One needs to be assessed by a trained clinician to ensure that you are investigated appropriately and that the findings are interpreted correctly.
If you are symptomatic, this requires appropriate investigations. This is NOT screening.