Which of the following is a characteristic of tumor markers?

Tumor markers are substances, often proteins, that can be found in the blood, urine, or tissues and are associated with the presence of cancer. The correct answer highlights that tumor markers can indeed be elevated in both malignant (cancerous) and non-malignant (non-cancerous) conditions. This elevation in non-cancerous settings can occur due to various factors such as inflammation, infection, or other benign diseases. For instance, markers like CA-125 can be high in conditions like endometriosis or pelvic inflammatory disease, while PSA can be elevated in benign prostatic hyperplasia.

In contrast, stating that tumor markers are specific only to malignant diseases (the first option) does not hold true since many markers can appear in benign conditions as well. Claiming they are utilized only for diagnosis (the third option) also misrepresents their role; tumor markers can be valuable for monitoring treatment response and disease recurrence, not just for initial diagnosis. Lastly, the assertion that they are always present in healthy individuals (the fourth option) is also incorrect, as some tumor markers may not be detectable or may be present at lower levels in healthy individuals, highlighting the complexity of their interpretation. Thus, the ability of tumor markers to be elevated