Added-value of SPECT/CT in Patients Undergoing LM/SL for Gynecological Cancers

Overview

Nodal staging is a key-step in pre-treatment assessment of gynecological cancers. In recent years, lymphatic mapping and sentinel lymphadenectomy (LM/SL) as a minimally invasive pelvic lymph nodes staging has been successfully evaluated in women with early stage of vulvar cancer, cervical cancer, and endometrial cancer. Such a technique may offer several valuable advantages: a) it is readily applicable in clinical routine using a safe, inexpensive, and reproducible protocol; b) it may help to avoid the cost and the morbidity of unnecessary lymphadenectomy in the majority of cases with uninvolved sentinel lymph nodes; c) it has the potential to guide the surgeon to nodal regions that are not routinely dissected (i.e. pre-sacral, para-aortic nodes) and to identify micro-metastases that would have been ignored otherwise; d) it also offers the basis for sophisticated pathological analysis to detect sub-microscopic nodal metastases using either immunohistochemical or molecular biological techniques. So far, within the abdomen and the pelvis, the LM/SL technique alone is often blinded to the accurate localization of SLNs. The integration of computed tomography (CT) to single photon emission computed tomography (SPECT) devices in a single gantry (SPECT/CT) has allowed a significant gain in terms of diagnostic accuracy and anatomic precision; clinical examples include malignant melanoma, head and neck cancer, breast cancer, and bladder cancer. In a seminal series of 26 patients with cervical cancer (Zhang et al., 2006), SPECT/CT was recently found superior to conventional planar imaging for detection of SLN and accurate localization. A more recent study (Kushner al., 2007) has also highlighted the technical feasibility and the clinical added-value of a low-dose SPECT/CT in a series of 20 patients with early stage cervical cancer (IA2-IIA) who underwent LM/SL. In the light of the encouraging data from literature and our own preliminary clinical experience, we hypothesized that the use of LM/SL plus SPECT/CT may be of clinical interest in patients with gynecological cancers.

This clinical trial is aimed at assessing the utility of a minimally invasive surgery preoperatively guided by a new nuclear medicine imaging procedure called SPECT/CT. In patients suffering from an early stage of gynecological cancer with no clinical evidence of lymph node involvement, there is theoretically no reason to perform systematically an aggressive lymphadenectomy as demonstrated for other types of lymphophilic cancers such as malignant melanoma, breast cancer, and head and neck cancer. We plan to follow a well known and safe procedure in Nuclear Medicine called lymphatic mapping and sentinel lymphadenectomy (LM/SL). The patient will be injected by the gynecologist referee in the department of Nuclear Medicine. These injections consist of a radioactive tracer routinely used in Nuclear Medicine, which allows the detection of the first nodes draining the primary tumor. The so-called sentinel lymph node (SLN) may be different from the lymph nodes anatomically predefined. As well demonstrated for other cancers, including those mentioned above, we hypothesized that the histological status of the SLN may accurately reflect the histological status of the entire nodal basin. If this assumption is clinically validated, the minimally invasive procedure may avoid the cost and the morbidity of unnecessary complete lymph node dissections in the majority of patients with uninvolved SLNs. The originality of this clinical trial also relies upon the use of a new hybrid imaging device called SPECT/CT, which allows the ability to obtain in a single study both functional and anatomical information. This is critical to precisely guide the surgeon in his task. No contrast medium will be injected during this study. The radiation exposure remains within the limits accepted worldwide; for instance, the CT dose index (CTDI) will be 3.0 mGy, which is in the order of the yearly natural background radiation exposure (\< 2mSv). In this clinical trial, all patients will be treated according to the standard of care currently applied for gynecological cancers. Therefore, either the hysterectomy or the vulvectomy will be followed by a complete lymph node dissection (CLND). Overall, the research protocol will be carried out in a 1-day protocol including the SPECT/CT guided LM/SL and the CLND.