A national study involving 17,424 patients found that the risk of developing gestational trophoblastic neoplasia following a complete molar pregnancy may be low—especially when human chorionic gonadotropin levels normalize within 56 days of uterine evacuation.
Investigators analyzed patient records from two UK treatment centers spanning 40 years. All patients had histologically confirmed complete molar pregnancies and achieved normal human chorionic gonadotropin (hCG) levels following evacuation. Among the total cohort, just 31 developed gestational trophoblastic neoplasia (GTN), representing an overall risk of 0.2%.
GTN risk varied significantly depending on the time to hCG normalization. Among patients whose hCG normalized in less than 56 days, the risk was 0.06% (about 1 in 1,667 patients). Among those whose normalization took 56 days or more, the risk was 0.22% (about 1 in 455 patients).
“If a patient had normal levels of hCG in < 56 days, the risk of developing gestational trophoblastic neoplasia was small (0.04%, about 1 in 2,619 patients) 39 months after normalization of hCG levels,” said lead study author Brenna E. Swift and colleagues. The equivalent risk for a patient who achieved normalization of hCG levels ≥ 56 days was 0.16% (about 1 in 642 patients).
The investigators used statistical models to track GTN risk over time. In patients with early hCG normalization, the risk increased only slightly over the years. In contrast, those with delayed normalization showed a gradual but consistent increase in risk.
Most GTN cases (71%, or 22 of 31) were diagnosed after the standard 6-month surveillance period. All patients were treated successfully and reached remission. One patient later died from leukemia, attributed to prior chemotherapy rather than the disease itself.
Common presenting symptoms included elevated hCG levels and vaginal bleeding. About 26% of cases involved metastatic disease at diagnosis, most frequently affecting the lungs, brain, or vagina.
In some cases, genetic testing confirmed that the GTN originated from the original molar pregnancy. In a few others, GTN may have resulted from a different subsequent pregnancy, potentially inflating the risk attributed to the initial mole.
Based on their findings, the investigators suggested that patients whose hCG normalizes in under 56 days could safely discontinue surveillance after a single confirmatory normal test—similar to current recommendations for partial molar pregnancies. Among those with delayed normalization, continued monitoring may still be appropriate, but the study provided data to inform individualized care decisions.
The investigators noted that these findings could support revised surveillance protocols that reduce unnecessary follow-up, lessen patient anxiety, and allow for earlier family planning. They emphasized the need for patients to remain vigilant for symptoms even after surveillance ends.
The authors reported no conflicts of interest.
Source: BMJ Medicine
