Modern radiotherapy and cervical cancer.

For most cervical cancers, radiotherapy is the mainstay of treatment. The introduction of concurrent chemotherapy to radiation at the end of the 20th century led to a significant improvement in disease survival. Now, techniques such as intensity-modulated radiotherapy, which allow a high degree of conformity to the tumor, offer the opportunity to further improve outcome by reducing treatment-related toxicity and also to potentially improve local control by an increase in tumor dose. This review will outline the history and current state of play of cervical radiotherapy.

A verification study of proposed pelvic lymph node localisation guidelines using nanoparticle-enhanced magnetic resonance imaging.

BACKGROUND AND PURPOSE: Normal sized pelvic lymph nodes are not easily identifiable on conventional imaging, but can be visualised with contrast-enhanced magnetic resonance imaging (MRI) using intravenous ultra-small particles of iron-oxide (USPIO). We have previously reported pelvic node clinical target volume (CTV) delineation guidelines for use with conventional imaging, derived from nodal mapping studies using USPIO. This study aims to verify these guidelines using an independent observer in a further patient cohort. MATERIALS AND METHODS: Ten patients with gynaecological cancer underwent MRI with and without intravenous USPIO. The guidelines were used to outline a pelvic node CTV on pre-contrast T2-weighted images. On post-contrast T2-weighted images the pelvic nodes were identified and outlined. The pre- and post-contrast images were co-registered and CTV examined for node coverage. RESULTS: By applying the guidelines, full coverage of 737 of 741 node outlines was achieved (>99%). Four nodes were not completely encompassed, two anterior external iliac nodes and two lateral external iliac nodes. CONCLUSIONS: MRI with USPIO contrast enabled the production of guidelines for localising a pelvic node CTV with conventional imaging. Application of these guidelines to a further patient cohort resulted in coverage of 99.5% node outlines demonstrating the reliability of this technique.

An assessment of interfractional uterine and cervical motion: implications for radiotherapy target volume definition in gynaecological cancer.

PURPOSE: To assess interfractional movement of the uterus and cervix in patients with gynaecological cancer to aid selection of the internal margin for radiotherapy target volumes. METHODS AND MATERIALS: Thirty-three patients with gynaecological cancer had an MRI scan performed on two consecutive days. The two sets of T2-weighted axial images were co-registered, and the uterus and cervix outlined on each scan. Points were identified on the anterior uterine body (Point U), posterior cervix (Point C) and upper vagina (Point V). The displacement of each point in the antero-posterior (AP), superior-inferior (SI) and lateral directions between the two scans was measured. The changes in point position and uterine body angle were correlated with bladder volume and rectal diameter. RESULTS: The mean difference (+/-1 SD) in Point U position was 7 mm (+/-9.0) in the AP direction, 7.1 mm (+/-6.8) SI and 0.8 mm (+/-1.3) laterally. Mean Point C displacement was 4.1 mm (+/-4.4) SI, 2.7 mm (+/-2.8) AP, 0.3 (+/-0.8) laterally, and Point V was 2.6 mm (+/-3.0) AP and 0.3 mm (+/-1.0) laterally. There was correlation for uterine SI movement in relation to bladder filling, and for cervical and vaginal AP movement in relation to rectal filling. CONCLUSION: Large movements of the uterus can occur, particularly in the superior-inferior and anterior-posterior directions, but cervical displacement is less marked. Rectal filling may affect cervical position, while bladder filling has more impact on uterine body position, highlighting the need for specific instructions on bladder and rectal filling for treatment. We propose an asymmetrical margin with CTV-PTV expansion of the uterus, cervix and upper vagina of 15 mm AP, 15 mm SI and 7 mm laterally and expansion of the nodal regions and parametria by 7 mm in all directions.

Mapping pelvic lymph nodes: guidelines for delineation in intensity-modulated radiotherapy.

PURPOSE: To establish guidelines for delineating the clinical target volume for pelvic nodal irradiation by mapping the location of lymph nodes in relation to the pelvic anatomy. METHODS AND MATERIALS: Twenty patients with gynecologic malignancies underwent magnetic resonance imaging with administration of iron oxide particles. All visible lymph nodes were outlined. Five clinical target volumes were generated for each patient using modified margins of 3, 5, 7, 10, and 15 mm around the iliac vessels. The nodal contours were then overlaid and individual nodes analyzed for coverage. The volume of normal tissue within each clinical target volume and planning target volume was also measured to aid selection of the margin that could provide maximal nodal, but minimal normal tissue, coverage. RESULTS: In total, 1216 nodal contours were evaluated. The nodal coverage was 56%, 76%, 88%, 94%, and 99% using vessel margins of 3, 5, 7, 10, and 15 mm, respectively. The mean volume of bowel within the planning target volume was 146.9 cm3 with a 7-mm margin, 190 cm3 with a 10-mm margin, and 266 cm3 with a 15-mm margin. Minor modification to the 7-mm margin ensured 99% coverage of the pelvic nodes. CONCLUSION: Blood vessels with a modified 7-mm margin offer a good surrogate target for pelvic lymph nodes. By making appropriate adjustments, coverage of specific nodal groups may be increased and the volume of normal tissue irradiated decreased. On the basis of these findings, recommended guidelines for outlining pelvic nodes have been produced.