ReviewImaging of endometrial adenocarcinoma
Introduction
Endometrial adenocarcinoma is the most common gynaecological malignancy and the fourth most frequent site of malignancy in females in North America and Europe. Incidence is rising due to increased life expectancy and rises in obesity.1, 2 Despite being a common malignancy it is not a leading cause of cancer deaths. This is due to early presentation with 75–80% presenting with stage I disease.3 The prognosis in stage I disease is good with 5-year overall and cancer specific survival rates of 80–85% and 90–95%, respectively.4 Prognosis also depends on age of patient, histological tumour grade, depth of myometrial invasion, cervical invasion, and lymph node metastases.3, 5, 6
Staging in endometrial cancer is surgical–pathological based on the FIGO (International Federation of Gynaecology and Obstetrics) system (Table 1).7 This is partly because most patients are treated surgically and also as clinical staging is inaccurate and often underestimates the extent of disease.3, 8, 9 Therefore since 1988 FIGO has required hysterectomy, bilateral salpingo-oopherectomy and pelvic/para aortic lymphadenectomy/lymph node sampling to stage endometrial cancer.7 This surgical–pathological staging system is independent of radiological staging or assessment. However, since the introduction of surgical staging there have been advances in imaging.
Modern imaging provides important tools in the preoperative assessment of endometrial cancer and may optimize treatment planning and the surgery to be undertaken.10 Without imaging the surgeon has to rely on preoperative tumour grade, which is often inaccurate, to guide operative management. However, there is no consensus on the role of imaging in the routine preoperative assessment of endometrial carcinoma and practice varies amongst many gynaecologists.11 The use of magnetic resonance imaging (MRI) in the assessment of myometrial invasion and cervical invasion is increasingly being recognized.10, 12, 13 More recently lymph node-specific contrast agents are emerging as useful tools in determining metastatic disease in lymph nodes.14 In this article we review the role of imaging in the diagnosis and staging/preoperative assessment of endometrial adenocarcinoma.
Section snippets
Primary diagnosis
Endometrial carcinoma most commonly presents with abnormal uterine bleeding, usually postmenopausal. Most patients presenting with postmenopausal bleeding have a benign cause such as endometrial atrophy, endometrial polyps, and non-uterine causes. Endometrial carcinoma accounts for 7–14% of cases of postmenopausal bleeding.15, 16, 17, 18 Consensus regarding evaluation of women with postmenopausal bleeding has not been reached and practice varies depending on resources and the physician's
Staging/preoperative assessment
The clinical challenge in endometrial cancer is to effectively select patients at risk of relapse for more radical surgery (e.g. lymphadenectomy) and adjuvant treatment whilst avoiding over treating low-risk cases.32 This is important as endometrial cancer predominately occurs in postmenopausal women with co-morbidities such as obesity, hypertension and diabetes.33, 34
Recent modifications of surgical (such as laparoscopic) techniques are emerging as alternatives for patients with early disease.
Imaging assessment of endometrial cancer
Histological diagnosis before staging is essential as imaging cannot accurately differentiate endometrial carcinoma from blood clot or hyperplasia.57
MRI is considered the most accurate imaging technique for preoperative assessment of endometrial cancer due its excellent soft-tissue contrast resolution. Overall staging accuracies have been reported at 83–92% (See Table 2).12, 58, 59 In comparative studies between computed tomography (CT), MRI and TVS; TVS is considered more accurate than CT for
MRI
Our MRI technique protocol is shown in Table 3.
The normal zonal uterine anatomy is clearly delineated on T2-weighted imaging. Endometrial carcinoma typically is isointense to myometrium on T1-weighted sequences and lower signal intensity than endometrial lining on T2-weighted sequences. Tumours are usually of lower signal intensity than the brightly enhancing normal myometrial tissue after contrast medium administration, and on dynamic contrast enhancement enhance more slowly than the
Myometrial invasion (stage I disease)
Stage 0 tumour (carcinoma in situ) is not visualized on MRI. Tumours are diagnosed as confined to the endometrium (stage IA) when the JZ appears intact (Fig. 2). Myometrial invasion is detected by disruption or discontinuity of the JZ. In patients in whom the JZ in not visible or indistinct, a smooth interface between the endometrium and the myometrium is considered to represent an intact myometrium. Conversely an irregular interface suggests myometrial invasion (stage IB or C; Fig. 3). In
Cervical invasion (stage II disease)
On T2-weighted imaging normal cervical stroma is hypointense and the endometrial carcinoma is hyperintense. In stage IIA disease, invasion of the endocervix, there is widening of the endocervical canal and internal os with preservation of the cervical stroma. In stage IIB there is invasion of cervical stroma (Fig. 5).
Dynamic contrast-enhanced MRI in combination with T2-weighted imaging is useful in assessing cervical involvement.13 The accuracy of MRI in cervical involvement is reported as
Locally advanced and nodal disease (stage III & IVA)
Stage III disease spreads outside the uterus but not beyond the true pelvis. In stage IIIA disease (extension to serosa, adnexa or positive peritoneal cytology) the integrity of the outer myometrium may be disrupted with direct extension to ovaries or discrete ovarian metastases. In stage IIIB disease there is tumour extension into upper vagina.
In stage IIIC there is lymph node involvement (Fig. 6). The location of nodal metastases corresponds to the drainage sites of the involved portions of
Metastatic spread (stage IVB)
Distant spread to lung, liver and bones is rare at presentation and usually occurs haematogenously. The lung is the most common site of distant metastases and is involved in 2–3% of patients.5 Patients with distant spread are more likely to have poorly differentiated/anaplastic cancers.
Summary
TVS in combination with pipelle biopsy or hysteroscopy is best for diagnosis of endometrial carcinoma. Radiological staging should only be carried out after histopathological confirmation of endometrial carcinoma as imaging cannot differentiate adequately between carcinoma and other causes of endometrial thickening.
MRI is reliable in predicting depth of myometrial invasion and cervical extension with greater sensitivity and accuracy than TVS and CT. As depth of myometrial invasion and cervical
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