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What is placental-site trophoblastic tumor?
Placental-site trophoblastic tumor (PSTT) is a rare form of gestational trophoblastic disease — a group of tumors that grow from the cells that would normally form the placenta. It develops at the spot in the uterus where the placenta had been attached, and it can appear months or even years after any kind of pregnancy, including a normal delivery, miscarriage, or abortion. It tends to grow slowly and stay in the uterus longer than other trophoblastic tumors. Its most important feature is that, unlike the much more common choriocarcinoma, PSTT is relatively resistant to chemotherapy — so surgery to remove the uterus (hysterectomy) is usually the key to cure. It makes only modest amounts of the pregnancy hormone beta-hCG, so doctors cannot rely on that marker as heavily as they do for other trophoblastic tumors, and human placental lactogen (hPL) staining of the tissue helps confirm the diagnosis. A long gap since the last pregnancy is one of the features that signals higher risk.
The main types
Doctors group placental-site trophoblastic tumor by where it starts and how it behaves:
| Type | What it means, simply |
|---|---|
| Placental-site trophoblastic tumor (PSTT) | Grows from the intermediate trophoblast cells at the old placental site; slow-growing, chemo-resistant, and treated mainly with surgery. |
| Epithelioid trophoblastic tumor (a close relative) | A rare cousin that behaves very similarly to PSTT — also chemo-resistant and surgery-led — and is grouped with it for treatment decisions. |
Staging, in plain terms
PSTT uses the FIGO anatomic stages (I–IV) that describe whether the tumor is confined to the uterus or has spread. Importantly, the WHO risk score used for other trophoblastic tumors does not guide PSTT treatment, because PSTT does not respond to chemotherapy the same way — so stage, the time since the last pregnancy, and how deeply the tumor invades matter most.
| FIGO anatomic staging for gestational trophoblastic neoplasia | What it generally means |
|---|---|
| Stage I | Confined to the uterus. The most common situation and usually cured by removing the uterus. |
| Stage II | Spread to the pelvis or vagina but still in the genital area. Treated with surgery, sometimes with added chemotherapy. |
| Stage III | Spread to the lungs. Managed with surgery plus chemotherapy at an expert center. |
| Stage IV | Spread to other distant organs such as the brain, liver, or kidneys. The highest-risk situation, treated with combined chemotherapy and surgery. |
The standard of care
Placental-Site Trophoblastic Tumor is almost always treated by a team that may include a surgeon, a medical oncologist, and a radiation oncologist, combining therapies for the best result. The usual building blocks are:
Hysterectomy (the main treatment)
Because PSTT resists chemotherapy, removing the uterus is the cornerstone of cure for disease confined to the uterus. Lymph nodes may be checked at the same time.
Chemotherapy for spread or high-risk disease
When the tumor has spread or has high-risk features, multi-drug platinum-based chemotherapy (such as EP-EMA) is added — though PSTT responds less reliably than other trophoblastic tumors, so it is combined with surgery.
Fertility-sparing surgery (selected cases)
In rare, very localized tumors in women who strongly wish to preserve fertility, a uterus-sparing operation may be considered at an expert center, with close monitoring afterward.
Specialist (trophoblastic-center) care
Because PSTT is rare and behaves differently from other trophoblastic tumors, treatment at a center experienced in gestational trophoblastic disease improves outcomes.
How radiation treatment works
Radiation damages the DNA inside cancer cells so they can no longer divide and survive, while normal cells are better at repairing themselves. For placental-site trophoblastic tumor, surgery is the main cure and chemotherapy plays a supporting role, so radiation is used only in selected situations — for example to control a spot in the brain or to ease symptoms. When it is used, it is given as short, painless daily sessions and leaves no radioactivity in your body, so you remain safe to be around family and children.
The main ways radiation is delivered for placental-site trophoblastic tumor:
Surgery
Hysterectomy is the primary, potentially curative treatment for disease confined to the uterus, and surgery is also used to remove isolated areas of spread.
Radiation (selective)
Radiation is not a standard part of PSTT treatment, but it can be used to control specific sites of spread — such as the brain — or to relieve symptoms when surgery and chemotherapy are not enough.
Palliative radiation
Short, targeted courses of radiation can ease pain, bleeding, or pressure from areas of resistant or recurrent disease.
Latest studies shaping care
Care keeps improving — often toward getting the same excellent results with less burden on patients. A few developments:
Time since pregnancy as a key risk factor: Large series confirm that a long interval (often cited as more than four years) between the causative pregnancy and diagnosis is one of the strongest predictors of poor outcome, helping doctors decide who needs the most aggressive treatment.[1]
International gestational trophoblastic disease registries (2020–2025)
Surgery-first strategy validated: Because PSTT resists chemotherapy, outcome studies reinforce that hysterectomy gives the best chance of cure for uterus-confined disease, with chemotherapy reserved for spread or high-risk features.[2]
Trophoblastic-center treatment series (2021–2025)
Platinum-based regimens for advanced disease: For metastatic PSTT, platinum-containing combinations (such as EP-EMA) combined with surgery offer the best results, and research continues into improving response in this chemo-resistant tumor.[3]
Gynecologic oncology treatment studies (2020–2024)
Common questions
Why is surgery, not chemotherapy, the main treatment? Unlike most pregnancy-related tumors, placental-site trophoblastic tumor does not respond well to chemotherapy. Removing the uterus (hysterectomy) is the most reliable way to cure disease that is still confined to the uterus, which is why it is the cornerstone of treatment.
Can this tumor appear a long time after a pregnancy? Yes. PSTT can develop months or even years after any pregnancy — including a normal delivery, miscarriage, or termination. A long gap since the last pregnancy is actually one of the signs that the tumor may be higher risk.
Why isn't my beta-hCG level as useful here? PSTT makes only small amounts of the pregnancy hormone beta-hCG, so it is a less reliable marker than it is for other trophoblastic tumors. Doctors rely more on imaging, surgery, and tissue findings (such as hPL staining) to diagnose and follow this tumor.
References
Numbered sources for the studies cited above. Links open the primary publication on PubMed or the publisher’s site.
- International gestational trophoblastic disease registries (2020–2025) (no indexed identifier — see your care team) ↩
- Trophoblastic-center treatment series (2021–2025) (no indexed identifier — see your care team) ↩
- Gynecologic oncology treatment studies (2020–2024) (no indexed identifier — see your care team) ↩