Molar pregnancy is an abnormal form of pregnancy in which tissue that normally develops into a fetus instead becomes an abnormal growth in the uterus. Even though there is no embryo, the growth triggers symptoms of pregnancy. Women with high, although decreasing human chorionic gonadotropin (hCG) concentrations can be treated with chemotherapy six months following molar pregnancies.

A new study published Online First in The Lancet shows that unnecessary exposure to chemotherapy together with its side-effects can be avoided in these women given that hCG levels will decrease spontaneously in most cases and it is therefore appropriate to place these women under a surveillance-only policy.

About one to three of 1,000 pregnancies are either complete or partial molar pregnancies. The relative risk of being affected by hydatidiform moles is higher in women younger than 16 years and above the age of 45 years, although it can affect women of any reproductive age.

Approximately 10% of affected females develop gestational trophoblastic disease after molar pregnancies. These are indicated by raised hCG concentrations 6 months after the hydatidiform mole has been removed from the uterus, even if those hCG values are decreasing.

Professor Michael J Seckl of Charing Cross Hospital at the Imperial College Healthcare NHS Trust in London, UK, and his team decided to investigate whether chemotherapy is always required in these patients.

They retrospectively identified women with persistently high hCG concentrations 6 months after evacuation of their hydatidiform mole who were registered at the Charing Cross Hospital in London, UK between January 1993 and May 2008. They examined rates of hCG normalization, relapse, and death in patients who received chemotherapy after 6 months, and those who were kept under surveillance only. The researchers proposed that if hCG values returned to normal in 75% of patients or more, a surveillance policy would be clinically acceptable.

Six months after evacuation, less than 1%, i.e. only 76 from 13,960 patients with hydatidiform moles showed persistently high hCG concentrations of more than 5 IU/L. They discovered that from 66 (87%) of patients without chemotherapy, who continued to be under surveillance, hCG levels spontaneously returned to normal in 65 (98%) with one patient not achieving normal levels due to chronic renal failure, although she remains healthy. They also found that of ten patients receiving chemotherapy, hCG levels returned to normal in 8 (80%) women and remained marginally higher in two women without being linked to clinical problems off treatment. The researchers did not record any deaths.

In a concluding statement the researchers say:

"Our findings suggest that the practice of close surveillance could be adopted in the knowledge that these women are not being exposed to a significantly increased risk of life-threatening gestational trophoblastic neoplasia including placental site trophoblastic tumor.

As far as we are aware, our study is the first to investigate whether continued hCG surveillance is a clinically acceptable approach as opposed to chemotherapy. Our findings directly challenge the present clinical dogma, and provide data showing that continued surveillance for women with high but falling hCG concentrations 6 months after uterine evacuation of a molar pregnancy is clinically acceptable because nearly all patients will spontaneously remit.

The results are important because they will change international practice and spare women unnecessary exposure to chemotherapy and its toxic effects."

Professor Annie N Y Cheung and Dr Karen K L Chan of the University of Hong Kong and Queen Mary Hospital in Hong Kong, China, write in a linked comment:

"The present recommendation from the International Federation of Gynecology and Obstetrics (FIGO) for chemotherapy when hCG is high for more than 6 months after evacuation is a compromise between too much and too little treatment. We believe that patients with gestational trophoblastic neoplasia should be managed in centers with dedicated specialists.

Centers using various criteria for initiation of chemotherapy, including those adopting FIGO guidelines, should be encouraged to report treatment outcomes so that the recommendations can be updated for improved management of this small but intriguing group of patients."

Lead author, Professor Seckl, also discussed a woman who previously had several molar pregnancies and who, with the help of her cousin acting as an egg donor, successfully gave birth to a healthy boy. The Case Report was published Online First.

According to Professor Seckl this is the first report which demonstrates that egg donation can allow successful pregnancy in women with a particular form of genetic mutation that has caused their molar pregnancy.

Written by Petra Rattue