Final answer:
CEA is considered for asymptomatic patients primarily for monitoring potential recurrence of bowel cancer post-treatment. Rising CEA levels could indicate cancer's return and necessitate further diagnostic tests. A pattern of low CEA levels can provide reassurance to patients about their remission status.
Step-by-step explanation:
Carcinoembryonic antigen (CEA) is often used as a tumor marker in the management of certain cancers. It is predominantly associated with gastrointestinal cancers but can also be elevated in lung and breast cancers. The indication for considering CEA in asymptomatic patients primarily falls within the context of monitoring for cancer recurrence, especially in individuals with a history of treated bowel cancer. An increasing trend in CEA levels could suggest a return of cancer and warrant further diagnostic workup, such as PET scans, even before any abnormality is detected through imaging or physical examination.
Conversely, a consistent pattern of low CEA levels post-treatment offers reassurance to patients about the absence of cancer recurrence. Nonetheless, it's crucial to remember that CEA is not a definitive test for cancer presence or recurrence; hence, its usage should be carefully considered in conjunction with other clinical assessments and diagnostic tools.