Lymphoscintigraphy in gynecologic malignancies

How iliopelvic lymphoscintigraphy can affect the definition of planning target volume in radiation therapy of pelvic and testicular tumors

PURPOSE

External beam radiation therapy (EBRT) of most intrapelvic and testicular tumors has been generally performed with large fields encompassing both the primary disease and lymphatic drainage. This study was carried out to map the pelvic and periaortic lymphatics by means of iliopelvic lymphoscintigraphy (IPL) in preparation for radiotherapy planning.

METHODS AND MATERIALS

Between January 2000 and October 2001, 70 patients scheduled for EBRT (61 operated on, 52 females, 18 males, mean age 61, range, 24-80), affected with uterine (43), rectal (11), testicular (8), anal (4), penile (2), and vulvar (2) cancers were enrolled in the study. IPL was performed by injection of 99mtechnetium-nanocolloids in the bipedal (70 cases) or bipedal plus perianal (20 cases) sites. The sensitivity of IPL in mapping the lymphatic anatomy was evaluated first. Then three radiation oncologists scored the modifications induced by IPL on the planning target volume (PTV) which had been previously delineated only on the basis of bony landmarks. The original fields were classified "inadequate" if they failed to match the new PTV by more than 1 cm.

RESULTS

IPL sensitivity in showing the inguinal, external iliac, common, and periaortic lymphatics was 100%, 90%, 80%, and 70% in anterior-posterior (A-P) projections, and 100%, 80%, 70%, and 60% in lateral projections respectively. For the presacral and hypogastric ones the sensitivity was 40%. When compared with bony landmarks, IPL changed the delineation of PTV in 24 of 70 A-P P-A fields (34%) and 22 of 58 (38%) lateral fields. Furthermore, 8/12 (67%) lymphadenectomies resulted in being incomplete. No IPL-related toxicity was observed.

CONCLUSION

IPL is a safe, inexpensive (cost: 100 Euros), and effective method to map the lymphatic chains. In the A-P scintigrams these structures were detected in 85% (70-100%) of the patients referred for total pelvis irradiation, and this figure could be higher in subjects not operated on. IPL can also give a reliable evaluation of the lymphadenectomies in order to schedule the proper treatments after surgery. Finally, IPL may change the conventional PTV for pelvic irradiation in about 36% (34-38%) of the cases; therefore, the fields should be tailored more around the lymphatic landmarks than the bony landmarks.

The use and abuse of imaging in gynecologic cancer

The radiologic detection in staging of gynecologic malignancies comprises a variety of noninvasive and invasive procedures. In the last few years, the emergence of the cross-sectional imaging techniques such as ultrasonography (US), computerized tomography (CT), and more recently, magnetic resonance imaging (MRI) have enabled the radiologist to determine more accurately the entire degree and extent of pathologic processes both within the pelvis and spread of disease outside the pelvis. The radiologist has also become more involved in invasive procedures such as percutaneous biopsies, aspirations of fluid collections, and transcatheter intraarterial infusion and occlusions. Although the newer imaging modalities will be emphasized, an attempt will be made to point out both their strengths and weaknesses relative to the older modalities. The discussion will concentrate on ovarian and cervical cancers while the other cancers of the female genital tract will be superficially discussed. The thrust of the presentation will emphasize the workup of gynecologic patients, that the workup may be quick, thorough, and as practical as possible.