Abstract

incidence and epidemiologyGestational trophoblastic disease (GTD) comprises a spectrum of disorders from the pre-malignant conditions of complete (CHM) and partial (PHM) hydatidiform moles through to the malignant invasive mole, choriocarcinoma (CC) and very rare placental site trophoblastic tumour/epithelioid trophoblastic tumour (PSTT/ETT). The malignant forms of the disease are also collectively known as gestational trophoblastic tumours or neoplasia (GTN). In the UK, all GTD cases are nationally registered, with central pathology review. The incidence is estimated at 1-3: 1000 pregnancies for CHM and 3: 1000 pregnancies for PHM, respectively, with other western countries reporting similar data [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. GTD appears to be more frequent in Asia than in North America or Europe. This may be because of discrepancies between hospital- and population-based data, availability of central pathological review or may reflect dietary and genetic influences. An increased risk of molar pregnancy is seen in the very young (45 years) [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. Following a molar pregnancy, the risk of a further CHM or PHM increases to ∼1%. After two molar gestations, the risk of a third mole is 15%–20% and is not decreased by changing partners.The frequency of CC and PSTT is less clear, since these can arise after any type of pregnancy. CC develops after around 1:50 000 deliveries, while recent data suggest that PSTT represents 0.2% of UK GTD cases [2.Schmid P. Nagai Y. Agarwal R. et al.Prognostic markers and long-term outcome of placental-site trophoblastic tumours: a retrospective observational study.Lancet. 2009; 374: 48-55Abstract Full Text Full Text PDF PubMed Scopus (164) Google Scholar]. GTN risk may also relate to hormonal factors since women with menarche after 12 years of age, light menstrual flow and prior use of oral contraceptives are at increased risk. Additionally, the subsequent risk of malignancy following a hydatidiform mole (HM) has been linked in some but not all series to oral contraceptives, if started while the human chorionic gonadotrophin (hCG) is still elevated [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. This hormone is essential for the diagnosis, management and subsequent surveillance of GTD and details regarding hCG and its measurement are provided in Box 1.Box 1.hCG measurementHCG comprises an alpha subunit common to all glycoprotein hormones including lutenising hormone (LH) and thyroid-stimulating hormone (TSH) and a specific beta subunit. Consequently, assays to detect hCG use antibodies directed against the beta subunit. In pregnancy, this subunit is usually intact and becomes hyperglycosylated particularly during the first trimester. In contrast, cancer-related beta hCG can exist in several different forms/fragments including nicked free beta, c-terminal peptide, hyperglycosylated and so it is essential that the hCG assay used to detect hCG in cancer patients can measure all forms of beta hCG equally well. There are currently many commercial hCG assays available that are very good for assessing hCG in pregnancy, but their ability to work well in cancer is less clear. Several reports indicate that some assays either fail to detect all the hCG isoforms/fragments or significantly under or over-read certain isoforms. This can lead to false-negative results and there are also several assays that appear to have particular problems with false-positive results. Clinicians need to be aware of these potential problems and when hCG results do not fit the clinical picture, they should measure the hCG on a different assay. When a false positive is suspected, assessment of the urine hCG can also be helpful as cross-reactive molecules in the blood that cause false positives rarely get into the urine. Consequently, a positive urine hCG excludes a false-positive serum result. Further details on hCG assays and monitoring in GTN are available in ref. [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar].diagnosis, genetics/molecular biology and pathologydiagnosisCHMs and PHMs most commonly present with vaginal bleeding in the first trimester of pregnancy. Previously reported features such as anaemia, uterine enlargement, pre-eclampsia, hyperemesis, hyperthyroidism and respiratory distress are now rare [3.Hou J.L. Wan X.R. Xiang Y. et al.Changes of clinical features in hydatidiform mole: analysis of 113 cases.J Reprod Med. 2008; 53: 629-633PubMed Google Scholar], reflecting the introduction of routine ultrasonography in early pregnancy. Characteristic sonographic findings for CHM in the second trimester, of a heterogeneous mass (‘snowstorm’), without foetal development and with theca-lutein ovarian cysts, are not seen in the first trimester, and ultrasonography is not diagnostically reliable [4.Fowler D.J. Lindsay I. Seckl M.J. Sebire N.J. Histomorphometric features of hydatidiform moles in early pregnancy: relationship to detectability by ultrasound examination.Ultrasound Obstet Gynecol. 2007; 29: 76-80Crossref PubMed Scopus (39) Google Scholar]. Indeed, false positive and negative rates are high with ultrasound, especially for PHM, and histological examination is essential to achieve a correct diagnosis [4.Fowler D.J. Lindsay I. Seckl M.J. Sebire N.J. Histomorphometric features of hydatidiform moles in early pregnancy: relationship to detectability by ultrasound examination.Ultrasound Obstet Gynecol. 2007; 29: 76-80Crossref PubMed Scopus (39) Google Scholar]. All products of conception from non-viable pregnancies must undergo histological examination regardless of ultrasound findings [5.Hinshaw K. Fayyad A. Munjuluri P. The management of early pregnancy loss.Green-top Guideline. Royal College of Obstetricians and Gynaecologists, London2006Google Scholar].The safest method of evacuation is suction dilation and curettage (D&C) under ultrasound control to ensure adequate emptying of uterine contents and to avoid uterine perforation [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. A proportion of women who miscarry or who undergo medical terminations will have unsuspected molar pregnancies. As histological examination is not routinely requested, the diagnosis of GTN can be delayed resulting in significantly greater morbidity [6.Seckl M.J. Gillmore R. Foskett M. et al.Routine terminations of pregnancy-should we screen for gestational trophoblastic neoplasia.Lancet. 2004; 364: 705-707Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar]. Histological examination of every termination is impractical, and perhaps a simple measurement of the urine or serum hCG level 3–4 weeks post-treatment to ensure return to normal is indicated [6.Seckl M.J. Gillmore R. Foskett M. et al.Routine terminations of pregnancy-should we screen for gestational trophoblastic neoplasia.Lancet. 2004; 364: 705-707Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar]. All women with a diagnosis of molar pregnancy require careful hCG monitoring to look for the recurrence of disease, suggesting malignant change indicated by a plateaued or rising hCG on three and two consecutive samples, respectively (see Box 1 for details about hCG testing) [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. Re-biopsy to confirm malignant change is not advised because of the risk of triggering life-threatening haemorrhage.The other malignant forms of GTD, CC and PSTT/ETT can be much more tricky to diagnose as the disease can develop months or many years after a prior pregnancy with protean presentations possible. Although change in menstruation is frequent, it does not always occur. It is therefore essential to measure the hCG in any woman of childbearing age who has unexplained metastatic disease. Biopsy of lesions without the ability to control bleeding is highly risky in this very vascular disease and is not essential before commencing chemotherapy. However, where complete excision is possible this can provide useful histological confirmation of the diagnosis and material for genetic analysis (see below).genetics/molecular biologyCHMs are usually diploid and androgenetic in origin, ∼80% resulting from duplication of the haploid genome of a single sperm while 20% arise by dispermic fertilisation of an ovum (Figure 1A and B). In either case maternal chromosomes are lost before, or shortly after, fertilisation. However, while nuclear DNA is entirely paternal in CHM, mitochondrial DNA remains maternal in origin [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar].Recent evidence indicates that some patients with recurrent CHM have diploid biparental CHM (BiCHM) rather than the typical androgenetic CHM (AnCHM) (Figure 1C). In these cases, the molar phenotype is due to an autosomal recessive condition, familial recurrent HM (FRHM) that predisposes women to recurrent pregnancy loss, most usually CHM. Mutations in two genes have now been associated with this condition: NLRP7 and, more rarely, KHDC3L. While women with recurrent AnCHM are likely to have normal live births in subsequent pregnancies and benefit from conventional in vitro fertilisation, women with FRHM are unlikely to achieve a normal pregnancy except through ovum donation from an unaffected individual [7.Fisher R.A. Lavery S.A. Carby A. et al.What a difference an egg makes.Lancet. 2011; 378: 1974Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar].PHMs are almost always triploid, usually as a result of fertilisation of an apparently normal ovum by two sperm or occasionally a diploid sperm (Figure 1D). The existence of diploid PHM is unlikely, most reported cases representing misdiagnosed complete moles, hydropic abortions or twin pregnancies.While most molar pregnancies are diploid CHM or triploid PHM, numerical and structural abnormalities have been reported in both CHM and PHM. In addition, CHM, and occasionally PHM, can be associated with a twin pregnancy with a coexistent normal twin [8.Sebire N.J. Foskett M. Paradinas F.J. et al.Outcome of twin pregnancies with complete hydatidiform mole and healthy co-twin.Lancet. 2002; 359: 2165-2166Abstract Full Text Full Text PDF PubMed Scopus (212) Google Scholar]. The continuance of such twin pregnancies results in healthy babies in ∼40% of cases, without an obvious increase in the risk of malignant change [8.Sebire N.J. Foskett M. Paradinas F.J. et al.Outcome of twin pregnancies with complete hydatidiform mole and healthy co-twin.Lancet. 2002; 359: 2165-2166Abstract Full Text Full Text PDF PubMed Scopus (212) Google Scholar].Since post-molar GTN is treated on a clinical, rather than pathological, diagnosis tumour tissue is rarely available for genetic analysis. However, where tissue is available from GTN, the genotype will reflect that of the causative pregnancy, having both maternal and paternal chromosomes if the tumour originated in a term pregnancy, hydropic abortion or PHM but only paternal genes if the causative pregnancy was a CHM. Since the interval from the causative pregnancy to the time of GTN diagnosis carries prognostic information, genotyping can be helpful particularly in patients with multiple pregnancies [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. Genetics can also be important in the differential diagnosis between gestational and non-gestational tumours, such as lung and gastric cancers, that can occasionally present as CC, but will have a genotype reflecting that of the patient [9.Fisher R.A. Savage P.M. MacDermott C. et al.The impact of molecular genetic diagnosis on the management of women with hCG-producing malignancies.Gynecol Oncol. 2007; 107: 413-419Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar]. These non-gestational CC often initially respond to GTN-based therapies, but their outcome is invariably poor, reflecting the originating tissue [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar].pathologyAll forms of GTD are derived from components of the normal human placenta; HM plus CC, and PSTT/ETT, representing abnormal counterparts of the villous and extravillous (interstitial) trophoblast, respectively. Most CHM and PHM have distinctive morphological characteristics, but it is recommended that cases of suspected GTD be reported by specialist histopathologists. CHMs show a characteristic villous architecture, associated with abnormal trophoblast hyperplasia, stromal hypercellularity, stromal karyorrhectic debris and collapsed villous blood vessels (Figure 2A). In contrast, PHMs show patchy villous hydropic change with scattered abnormally shaped irregular villi with trophoblastic pseudoinclusions and patchy trophoblast hyperplasia (Figure 2B) [10.Sebire N.J. Seckl M.J. Immunohistochemical staining for diagnosis and prognostic assessment of hydatidiform moles: current evidence and future directions.J Reprod Med. 2010; 55: 236-246Google Scholar]. The morphological distinction between non-molar miscarriage, especially when associated with chromosomal abnormality, and PHM can sometimes be difficult, and ancillary techniques may be required including immunostaining with p57KIP2 (negative in CHM), ploidy analysis by in situ hybridisation or flow cytometry or molecular genotyping. Genotyping can also be useful in the identification of BiCHM, associated with FRHM, since most are pathologically indistinguishable from typical AnCHM [11.Sebire N.J. Savage P.M. Seckl M.J. Fisher R.A. Histopathological features of biparental complete hydatidiform moles in women with NLRP7 mutations.Placenta. 2013; 34: 50-56Crossref PubMed Scopus (31) Google Scholar]. Unfortunately, there are no histological or immunohistochemical features that reliably predict which patients will subsequently develop persistent GTD (pGTD)/GTN, and hence all HMs require hCG surveillance.Figure 2Photomicrographs demonstrating the various histopathological forms of GTD. (A) Complete hydatidiform mole, (B) partial hydatidiform mole, (C) choriocarcinoma and (D) placental site trophoblastic tumour. All are characterised by abnormal forms of trophoblast proliferation, associated with dysmorphic chorionic villi in CHM and PHM, but no villi and abnormal trophoblast invasion in CC and PSTT. (Original magnifications ×40, ×20, ×200 and ×100, respectively.)View Large Image Figure ViewerDownload (PPT)CC (Figure 2C) are malignant hCG-producing epithelial tumours with differentiation towards a villous trophoblast phenotype, usually demonstrating central necrosis and characteristic biphasic architecture recapitulating cytotrophoblast-like cells and multinucleate, pleomorphic syncytiotrophoblast-like areas. Intraplacental CC are rare but probably represent the source of metastatic CC, which occur following apparently uncomplicated term pregnancies. PSTT (Figure 2D) is the malignant equivalent of extravillous interstitial implantation site-like trophoblast and forms uterine lesions with less haemorrhage and necrosis, and lower hCG levels, than CC. The histological features show locally infiltrating nests and sheets of monomorphic, interstitial-type trophoblast, with moderate pleomorphism and mitotic activity, and expression of human placental lactogen (hPL) and other extravillous trophoblast markers. A specific variant of PSST with distinctive hyalinisation and a slightly different immunohistochemical profile has been reported, ETT which is clinically thought to behave like PSTT [12.Shih I.M. Kurman R.J. Epithelioid trophoblastic tumor: a neoplasm distinct from choriocarcinoma and placental site trophoblastic tumor simulating carcinoma.Am J Surg Pathol. 1998; 22: 1393-1403Crossref PubMed Scopus (280) Google Scholar].staging and risk assessmentindications for treatmentFollowing suction curretage of a PHM, patients should have anti-Rhesus D prophylaxis. After any HM, the onset of malignant change, referred to as pGTD or post-mole GTN, is nearly always indicated by a plateaued or rising hCG (Table 1). In the UK, this occurs after 15% and 0.5%–1% of CHM and PHM, respectively [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. In other countries, these rates may be higher, possibly reflecting differences in hCG assays, hCG criteria for the diagnosis of GTN, lack of whole population demographics or, less likely, a genuine difference in disease biology. The precise hCG surveillance protocol varies by country, but principles are similar. In the UK, serum and urine hCG is measured two weekly until normal and then monthly in urine [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. The durations of monitoring once the hCG is normal also vary between countries, reflecting uncertainty around the importance of a very low risk of disease recurrence once the hCG is normal. Women completing the UK scheme have an estimated 1:2000 chance of missed disease [13.Sebire N.J. Foskett M. Short D. et al.Shortened duration of human chorionic gonadotrophin surveillance following complete or partial hydatidiform mole: evidence for revised protocol of a UK regional trophoblastic disease unit.BJOG. 2007; 114: 760-762Crossref PubMed Scopus (53) Google Scholar], but the risk is already very low with the first normal hCG value even for CHM. The UK indications for commencing chemotherapy are listed in Table 1 and are broadly similar to those of the International Federation of Gynecology and Obstetrics (FIGO) [14.Kohorn E.I. Negotiating a staging and risk factor scoring system for gestational trophoblastic neoplasia. A progress report.J Reprod Med. 2002; 47: 445-450PubMed Google Scholar]. The commonest is a plateaued or rising hCG, but others include a tissue diagnosis of CC and spread to other organs. However, our UK experience indicates that the disease is also unlikely to spontaneously remit if the hCG is >20 000 IU/l 1 month after HM evacuation (also associated with an increased risk of uterine perforation) or there are lung or vaginal metastasis of >2 cm (smaller lesions may spontaneously regress) [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. In addition, in the UK, chemotherapy is started to help stop heavy bleeding that requires transfusion even if the hCG is falling. Interestingly, recent data have overturned the previous UK and FIGO guidance that women who continue to have a falling hCG 6 months after uterine evacuation automatically need chemotherapy. Indeed, the hCG spontaneously normalised in all such individuals left on surveillance [15.Agarwal R. Teoh S. Short D. et al.Chemotherapy and human chorionic gonadotropin concentrations 6 months after uterine evacuation of molar pregnancy: a retrospective cohort study.Lancet. 2012; 379: 130-135Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar]. Thus, this indication for chemotherapy has now been removed from UK guidelines.Table 1UK indications for chemotherapy following the diagnosis of GTDIndications for chemotherapy Plateaued or rising hCG after evacuationaPlateaued or rising is defined as four or more equivalent values of hCG over at least 3 weeks (days 1, 7, 14 and 21) and two consecutive rises in hCG of 10% or greater over at least 2 weeks (days 1, 7 and 14), respectively. Heavy vaginal bleeding or evidence of gastrointestinal or intraperitoneal haemorrhage Histological evidence of choriocarcinoma Evidence of metastases in the brain, liver or gastrointestinal tract, or radiological opacities of >2 cm on chest X-ray Serum hCG of ≥20 000 IU/l >4 weeks after evacuation, because of the risk of uterine perforation Raised hCG 6 months after evacuation even if still falling (now omitted [15.Agarwal R. Teoh S. Short D. et al.Chemotherapy and human chorionic gonadotropin concentrations 6 months after uterine evacuation of molar pregnancy: a retrospective cohort study.Lancet. 2012; 379: 130-135Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar])a Plateaued or rising is defined as four or more equivalent values of hCG over at least 3 weeks (days 1, 7, 14 and 21) and two consecutive rises in hCG of 10% or greater over at least 2 weeks (days 1, 7 and 14), respectively. Open table in a new tab staging investigations and treatment stratification after a molar pregnancyMost patients developing GTN post-HM are detected early via hCG monitoring and so extensive investigation is rarely required. Information to determine therapy can be obtained from the clinical history, examination, measurement of serum hCG and a Doppler pelvic ultrasound to confirm the absence of a pregnancy, to measure the uterine size/volume, spread of disease within the pelvis and its vascularity (Figure 3). The latter assessed by the Doppler pulsatility index is an independent prognostic factor for resistance to single-agent methotrexate (MTX) therapy [16.Agarwal R. Harding V. Short D. et al.Uterine artery pulsatility index: a predictor of methotrexate resistance in gestational trophoblastic neoplasia.Br J Cancer. 2012; 106: 1089-1094Crossref PubMed Scopus (36) Google Scholar] and is now being evaluated in a prospective trial. Pulmonary metastases are most common, so a chest radiograph is essential [17.Berkowitz R.S. Goldstein D.P. Current management of gestational trophoblastic diseases.Gynecol Oncol. 2009; 112: 654-662Abstract Full Text Full Text PDF PubMed Scopus (219) Google Scholar]. Computed tomography (CT) of the chest is not required if the chest X-ray (CXR) findings are normal, since discovery of micrometastases, which may be seen in ∼40% of patients, does not influence outcome [18.Darby S. Jolley I. Pennington S. Hancock B.W. Does chest CT matter in the staging of GTN?.Gynecol Oncol. 2009; 112: 155-160Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar]. However, if lesions are noted on CXR, magnetic resonance imaging (MRI) of the brain and CT body are indicated (Figure 4) to exclude more widespread disease involving, for example, the brain or liver, which would significantly alter management.Figure 3Pelvic Doppler ultrasonography of persisting GTN following a HM. (A) Pre-chemotherapy. (B) Post-chemotherapy. (Reprinted from ref. [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar], Copyright 2010, with permission from Elsevier.)View Large Image Figure ViewerDownload (PPT)Figure 4Algorithm of imaging investigations for patients with GTN following a HM on hCG surveillance (left-hand panel) or after any other type of pregnancy (right-hand panel). USS, ultrasound scan; CT, computerised tomography; MRI, magnetic resonance imaging; PET, positron emission tomography; -ve, negative; +ve, positive; mets, metastases.View Large Image Figure ViewerDownload (PPT)FIGO reports data on GTN using prognostic scoring and anatomic staging systems (Table 2) [19.FIGO Oncology Committee. FIGO staging for gestational trophoblastic neoplasia 2000. International Journal of Gynecology & Obstetrics 77:285-287.Google Scholar]. Since 2002, all physicians treating GTN should use this system to enable the comparison of data. The prognostic score predicts the potential for developing resistance to single-drug chemotherapy with MTX or actinomycin D (ActD). A score of 0–6 and ≥7 indicates a low and high risk of resistance, respectively. The latter has almost no chance of being cured with single-drug therapy and requires multi-agent treatment. The anatomical staging does not help with determining therapy, but provides additional information to help clinicians who compare results between centres. The variables that are assessed in the prognostic score include: (i) tumour volume (hCG level, size of metastases and number of metastases), (ii) site of involvement, (iii) prior chemotherapy resistance and (iv) duration of disease from antecedent pregnancy (Table 2) [19.FIGO Oncology Committee. FIGO staging for gestational trophoblastic neoplasia 2000. International Journal of Gynecology & Obstetrics 77:285-287.Google Scholar].Table 2FIGO 2000 scoring system for GTNPrognostic factorScore0124Age (years)12hCG (IU/l)105Number of metastases01–45–8>8Site of metastasesLungSpleen and kidneyGI tractBrain and liverLargest tumour mass–3–5 cm>5 cmPrior chemotherapy––Single drug>2 drugsThe total score for a patient is obtained by adding the individual scores for each prognostic factor. Low risk, 0–6; high risk, ≥7. PSTT should not be scored and instead requires staging. Stage I, disease confined to the uterus; stage II, disease extending into the pelvis; stage III, disease spread to lungs and/or vagina; stage IV, all other metastatic sites including liver, kidney, spleen and brain. (Reprinted [19.FIGO Oncology Committee. FIGO staging for gestational trophoblastic neoplasia 2000. International Journal of Gynecology & Obstetrics 77:285-287.Google Scholar] Copyright 2002, with permission from Elsevier for the International Federation of Gynecology and Obstetrics.) Open table in a new tab staging investigations for CC and PSTT/ETTWomen who present with an elevated hCG and suspected GTN (CC or PSTT/ETT) following a prior pregnancy require much more extensive staging investigations, which include a contrast enhanced CT of the chest and abdomen, MRI of the brain and pelvis, a Doppler ultrasound of the pelvis and may benefit from a lumbar puncture to assess the cerebrospinal fluid to serum hCG ratio. The latter if more than 1:60 suggests occult central nervous system disease [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]. In addition, where there is doubt over the clinical diagnosis, tissue should be obtained and genetic analysis undertaken to confirm the gestational origin of the tumour through the presence of paternal genes. For CC, the FIGO scoring/staging system is the same as described above. However, PSTT/ETT has a discrete biological behaviour with less hCG production, slower growth, late metastasis and slightly less chemosensitivity. Consequently, the scoring system is not valid for PSTT/ETT, but FIGO staging is used to help adapt treatment intensity (see below). Some investigators have recently started using positron emission tomography (PET)/CT imaging, but experience is still quite limited. It appears that this imaging modality is more helpful in relapsed disease to identify sites for resection and, as with other cancers, is prone to both false-positive and false-negative results [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar].management of low-risk diseaseAbout 95% of patients with HM who develop GTN are low risk (score 0–6). In women with stage I disease apparently confined to the uterine cavity, the role of second D&C in reducing the need for chemotherapy remains controversial. UK results indicate that this procedure is only valuable if the hCG is <5000 IU/l with disease in the cavity rather than myometrium. Indeed, the low efficacy of a second D&C, small risks of introducing infection, causing haemorrhage and uterine perforation should be balanced against the almost 100% cure rate and relative safety of chemotherapy (reviewed in [1.Seckl M.J. Sebire N.J. Berkowitz R.S. Gestational trophoblastic disease.Lancet. 2010; 376: 717-729Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar]). Sometimes patients with stage I GTN who have completed their families request hysterectomy, which, although possible, may not completely obviate the need for chemotherapy.Consequently, for nearly all low-risk GTN patients, single-agent chemotherapy with either MTX or ActD is the preferred treatment. A variety of regimens have been developed, which in non-randomised, mostly retrospective, studies demonstrate a 50%–90% chance of inducing remission [20.Alazzam M. Tidy J. Hancock B.W. et al.First line chemotherapy in low risk gestational trophoblastic neoplasia.Cochrane Database Syst