ABSTRACT
The prognosis is considerably changed by the extent of spread: the 5-year survival rate is 85% if the cancer is confined to the ovaries (stage 1), 55% if the cancer has spread into the pelvis (stage 2), 14% for stage 3 abdominal spread, and 4% for stage 4 more distant spread.3 There are two major diagnostic challenges when an ovarian mass is detected: determination of malignancy and evaluation of tumor extent (staging). Diagnostic studies that allow accurate confirmation of benignity might reduce unnecessary surgery. On the other hand, diagnostic procedures that allow accurate cancer staging should help to determine surgical and chemotherapeutic planning.2,3 The current management of clinically suspected disease involves histological confirmation of the diagnosis, the identification of tumor spread, and debulking prior to chemotherapy, usually followed by second-look surgical procedures to assess the response.4,5 Because of the extremely poor prognosis for advanced ovarian cancer, suspicious ovarian masses need prompt attention. In fact, misleading symptoms of ovarian cancer often delay an early diagnosis. As a result, 75% of patients have stage 3 or 4 disease at the time of initial diagnosis.6-13 Accurate diagnosis of ovarian carcinoma is essential in the proper management of these patients. Measurement of the serum tumor marker CA125 may be used. However, its accuracy is limited because negative values do not rule out active disease, whereas elevated values cannot provide information on the site of tumor tissue.14-16 In the past decade, morphologic imaging modalities have played a major role in accurately delineating disease status: particularly, computed tomography (CT) and magnetic resonance imaging (MRI) have proved useful in evaluating the extent
of ovarian disease and evaluating the response to treatment in these patients.17-20
Primary ovarian cancer: diagnostic modalities Clinical pelvic examination and serum CA125 levels have failed to allow consistent detection of ovarian malignancy.14-16 As the sensitivities of these techniques are often below 50%, imaging modalities such as ultrasonography (US), CT, and MRI have become indispensable. US performed with transabdominal and endovaginal techniques has demonstrated accuracies of up to 80% in the evaluation of ovarian masses. US is better for the detection of masses than in the diagnosis of malignancy.17 Studies of contrast material-enhanced CT and MRI have shown accuracies of almost 80% in the diagnosis of cancer and 80-90% in the detection of abdominal spread.17-20 In general, comparative studies of US and MRI have shown MRI to be superior in the differentiation of benign from malignant masses.19,20
In previous reports, US, CT, and MRI were compared in diagnosing primary ovarian cancer.17,18 The three imaging modalities yielded similar estimated areas under the receiver operating characteristic (ROC) curve for discrimination between benign disease and cancer in all regions, with a mean area of 0.91 for all three modalities. Although the differentiation of benign from malignant disease is obviously clinically important, and these detection rates are higher than those previously reported, they are likely still not high enough for surgery to be avoided in most cases. The estimated areas under the ROC curve for each modality revealed that MRI and CT are superior to Doppler US for diagnosis of malignancy in the mass. It is unfortunate (but unavoidable) that the study design did not allow statistical evaluation of the performances of CT and MRI versus that of combined Doppler and conventional US. The relatively poor performance of Doppler US has been discussed without identification of a unifying cause. The neovascular response of ovarian cancer may be
incomplete or non-specific. Thus, when intratumoral arterial flow is detected with Doppler US, the differentiation of benign from malignant processes is often not possible. Therefore, whatever the reason, the present lack of specificity makes Doppler US a poor diagnostic tool. It is possible that different numerical cut-off values for the Doppler indices may provide more encouraging results, although the considerable overlap of the indices in benign and malignant tumors makes this possibility unlikely. Perhaps the use of intravenous contrast agents to enhance the tumor and its vascularity may improve diagnostic accuracy. Problems with both overstaging and understaging are also present with three morphologic imaging modalities.17-20 Overstaging leads to a wider surgical approach, but makes it more likely that malignancy will not be overlooked. Understaging causes extension of the originally planned pelvic surgery with the potential for a tumor to be overlooked. In most centers, the greater is the suspicion of abdominal spread, the more likely it is that a specialist in gynecologic oncology will perform the exploration. This point is important, because surgery by specialists leads to better staging and maximal debulking (cytoreduction) and to longer survival. Although one could argue that it is always better to overstage so that malignancy is not overlooked, it is more important to accurately distinguish malignancy that has spread into the abdomen (stage 3 or 4) from malignancy confined to the pelvis (stage 1 or 2).1-5
Because of the importance of not understaging abdominal malignancy as disease limited to the pelvis, if stage 3 cancer is not detected at initial abdominal US, CT or MRI should be performed because of their higher sensitivities in staging. Whatever the modality used, it is hoped that the correct staging of advanced disease will lead to appropriate referral to a specialist in gynecologic oncology.
