The tumor marker for Endodermal sinus tumor is
**Core Concept**
Endodermal sinus tumors, also known as yolk sac tumors, are a type of germ cell tumor that primarily affect the ovaries in females and the testes in males. These tumors are known for their aggressive behavior and are often associated with elevated levels of specific tumor markers.
**Why the Correct Answer is Right**
α-fetoprotein (AFP) is a well-established tumor marker for endodermal sinus tumors. Elevated levels of AFP are commonly observed in patients with this type of tumor, making it a valuable tool for diagnosis and monitoring. The production of AFP is thought to be related to the abnormal differentiation of embryonic cells within the tumor.
**Why Each Wrong Option is Incorrect**
**Option A:** β-hCG is a tumor marker associated with choriocarcinoma, another type of germ cell tumor, but not endodermal sinus tumors.
**Option B:** LDH is a nonspecific enzyme that can be elevated in various types of cancer, but it is not a specific marker for endodermal sinus tumors.
**Option C:** CEA is a tumor marker associated with various types of cancer, including colorectal, breast, and lung cancer, but it is not specific for endodermal sinus tumors.
**Clinical Pearl / High-Yield Fact**
AFP levels can be used to monitor the response to treatment in patients with endodermal sinus tumors, with a decrease in AFP levels indicating a positive response to therapy.
**Correct Answer: C. AFP (Alpha-fetoprotein)**