Clinicopathologic characteristics of primary vaginal clear cell carcinoma in China and an endometriosis malignant transformation case: a case series
Primary vaginal carcinoma is one of the rarest cancers affecting the female reproductive system, accounting for just 1 to 2 percent of all genital malignancies. Even more uncommon? Primary vaginal clear cell carcinoma (PVCCC), a subtype linked to prenatal diethylstilbestrol (DES) exposure in Western countries but poorly understood in China. A new study from Peking Union Medical College Hospital (PUMCH) offers the first detailed look at PVCCC in Chinese patients—including a rare case where vaginal endometriosis turned cancerous.
What the Study Did
Researchers from PUMCH’s Department of Obstetrics and Gynecology—led by Sikai Chen, Zhiyue Gu, and a team of pathologists and clinicians—reviewed 228 cases of vaginal malignancy treated at the hospital between 2010 and 2019. They identified 10 patients with PVCCC (confirmed by gynecologic pathologists) and analyzed their clinical features, treatments, survival rates, and exposure histories.
To ensure accuracy, the team:
- Extracted data from medical records (age at diagnosis, symptoms, pathology reports, treatments).
- Followed up with patients via phone or outpatient visits to track recurrence and survival.
- Surveyed 6 patients about DES or toxic substance exposure (a key risk factor for PVCCC in the U.S.).
The study was approved by PUMCH’s Ethics Committee, and all patients provided consent.
Key Findings
- Rarity of PVCCC: Of 228 vaginal malignancies, 11 were clear cell carcinoma (CCC)—and 10 were primary (not spread from other organs). PVCCC made up ~4.4% of primary vaginal cancers at PUMCH.
- Short-Term Survival: For the 5 patients with at least 3 years of follow-up, 100% survived without recurrence. Only one patient had a recurrence, which occurred 7 years after surgery.
- No DES Link: All 6 patients who completed exposure surveys denied DES or toxic substance contact. DES was never widely used in Chinese pregnancies (it was reserved for cancer treatment or estrogen replacement, with pregnancy as a strict contraindication), so this aligns with real-world use.
- Rare Endometriosis Transformation: One patient’s PVCCC developed from vaginal endometriosis—a benign condition where uterine-like tissue grows in the vagina. Pathologists confirmed the link by finding both endometriosis and cancerous clear cells in the same tissue sample. Endometriosis malignant transformation is rare, especially in the vagina (it’s more common in the ovaries).
What This Means for Patients and Doctors
- Treatment Aligns with Global Guidelines: PVCCC is treated like other vaginal cancers—surgery first (to remove the tumor), followed by chemotherapy or radiation. The team noted that concurrent chemoradiation (combining radiation with chemotherapy) improves survival, which matches international recommendations.
- Good Short-Term Prognosis: The 100% 3-year survival rate is encouraging, but late recurrences (like the 7-year case) mean long-term follow-up is critical.
- DES Isn’t a Risk Factor in China: Unlike in the U.S., where prenatal DES exposure drives most PVCCC cases, Chinese patients don’t face this risk. Doctors should focus on other potential causes (like endometriosis) when evaluating PVCCC.
Limitations to Consider
As with most rare disease studies, this one had constraints:
- Small Sample Size: Only 10 PVCCC cases were included.
- Follow-Up Gaps: Four patients were lost to follow-up, so exposure and survival data are incomplete.
- No Genetic Testing: The retrospective design meant the team couldn’t do molecular testing on all samples—so they couldn’t explore genetic causes of PVCCC in these patients.
Why This Study Matters
This is the first study to document PVCCC characteristics in the Chinese population. It fills a critical gap in global research by showing:
- PVCCC in China has a different risk profile (no DES link) than in Western countries.
- Short-term survival is excellent with standard treatment.
- Vaginal endometriosis can transform into PVCCC—something doctors should watch for in patients with long-standing endometriosis.
The researchers hope larger, prospective studies will build on these findings—especially to explore molecular drivers of PVCCC and long-term survival.
Original Study Details
This case series was published in the Chinese Medical Journal in 2022 by Sikai Chen, Zhiyue Gu, Jian Sun, Boju Pan, Qingbo Fan, Ping Zheng, Shu Wang, Jinhua Leng, Yang Xiang, and Jinghe Lang (from Peking Union Medical College Hospital and affiliated institutions).
You can access the full study at: doi.org/10.1097/CM9.0000000000001734
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