What is Placental Site Trophoblastic Tumor (PSTT)?
Placental Site Trophoblastic Tumor (PSTT) is a rare form of
gestational trophoblastic disease (GTD), which arises from the trophoblastic cells that normally form the placenta during pregnancy. These tumors are characterized by the proliferation of intermediate trophoblastic cells at the placental implantation site. Unlike other forms of GTD, PSTT grows slowly and may not produce high levels of human chorionic gonadotropin (
hCG), making it more challenging to diagnose.
What are the Causes and Risk Factors?
The exact cause of PSTT is not well understood. However, it is known to develop from
abnormal placental tissue that remains in the uterus after a normal pregnancy, miscarriage, abortion, or molar pregnancy. Risk factors may include a history of GTD, previous molar pregnancy, or a history of abnormal placental implantation.
What are the Symptoms?
Symptoms of PSTT can vary but often include
irregular vaginal bleeding, which may occur months or even years after a pregnancy. Other symptoms may include an enlarged uterus, pelvic pain, and sometimes symptoms related to metastasis if the cancer has spread. Due to its slow-growing nature, PSTT can often go unnoticed until it has progressed.
How is PSTT Diagnosed?
Diagnosis typically involves a combination of methods. Blood tests may be conducted to measure levels of hCG, although these levels are often lower in PSTT compared to other types of GTD. Imaging studies like
ultrasound,
CT scans, or
MRI are used to visualize the tumor. Definitive diagnosis is usually made through a biopsy, where tissue samples are examined for the presence of intermediate trophoblastic cells.
What are the Treatment Options?
Treatment for PSTT often involves
surgery, specifically a hysterectomy (removal of the uterus), as these tumors are generally resistant to chemotherapy. In cases where the tumor has metastasized, additional treatments like chemotherapy or radiation therapy may be considered. The choice of treatment depends on the stage of the disease, the extent of metastasis, and the patient's desire for future fertility.
What is the Prognosis?
The prognosis for PSTT varies depending on several factors including the stage at diagnosis and the extent of spread. Early-stage PSTT that has not spread beyond the uterus has a relatively good prognosis with appropriate surgical intervention. However, in advanced stages where the cancer has metastasized, the prognosis may be poorer. Regular follow-up is essential to monitor for recurrence.
What are the Follow-Up and Monitoring Guidelines?
After treatment, patients are typically monitored closely with regular follow-up visits. Monitoring may include periodic blood tests to measure hCG levels and imaging studies to check for any signs of recurrence. Long-term follow-up is crucial due to the risk of late recurrence, which can occur years after the initial treatment.
Conclusion
Placental Site Trophoblastic Tumor is a rare but significant form of cancer that arises from placental cells. Early diagnosis and appropriate treatment are key to improving outcomes. Due to its rarity, specialized care and attention are often required to manage this condition effectively. Awareness and understanding of PSTT can lead to better patient outcomes and improved quality of life for those affected by this unique form of cancer.
