Which tumor marker is primarily associated with ovarian cancer diagnosis and treatment assessment?

The tumor marker primarily associated with ovarian cancer diagnosis and treatment assessment is CA-125. This marker is a protein that is found at higher levels in the blood of many women with ovarian cancer, though it can also be elevated in other conditions. CA-125 is used primarily as a blood test to help in diagnosing ovarian cancer, monitoring treatment response, and checking for recurrence after treatment.

In the context of ovarian cancer, the presence of elevated CA-125 levels can provide critical information about the disease's status and how well the patient is responding to therapy. It is important to note that while CA-125 is a useful marker for diagnosis and monitoring, it is not exclusively used for screening; hence, it should be interpreted alongside other clinical findings.

In contrast, while other tumor markers mentioned have their specific roles, they are not primarily linked to ovarian cancer. For instance, AFP (alpha-fetoprotein) is mainly associated with liver cancer and germ cell tumors, ER/PR (estrogen and progesterone receptors) relate to breast cancer, and KRAS mutation analysis is typically used in colorectal cancer and other types for indicating a specific treatment plan. Therefore, CA-125 stands out as the most relevant tumor marker in the context of ovarian cancer.