Use of CT simulation for treatment of cervical cancer to assess the adequacy of lymph node coverage of conventional pelvic fields based on bony landmarks

Intensity Modulated Radiation Therapy and Image-Guided Adapted Brachytherapy for Cervix Cancer

PURPOSE

This study reported long-term outcomes of patients with cervical cancer who were treated with intensity modulated radiation therapy and 3-dimensional (3D) image-guided adapted brachytherapy (IMRT/3D-IGABT) compared with those treated with 2-dimensional (2D) external irradiation and 2D brachytherapy (2D EBRT/BT).

METHODS AND MATERIALS

This study included patients with newly diagnosed cervical cancer and pretreatment fluorodeoxyglucose positron emission tomography scans who were treated with curative-intent irradiation from 1997 to 2013. The treatment policy changed from using 2D EBRT/BT to IMRT/3D-IGABT in 2005. Patterns of recurrence, cancer-specific survival (CSS), and overall survival (OS) were evaluated. Late gastrointestinal and genitourinary toxicity were scored with National Cancer Institute Common Terminology Criteria for Adverse Events.

RESULTS

The median follow-up for patients alive at the time of last follow-up in the 2D EBRT/BT group (n = 300) was 15.3 years (range, 10.8-20.5 years). In the IMRT/3D-IGABT group (n = 300), it was 7 years (range, 5-12.4 years). According to the International Federation of Gynecology and Obstetrics, 33% of tumors were stage IB1 to IB2, 41% were stage IIA to IIB, and 26% were stage IIIA to IVA. The results after 5 years for patients treated with 2D EBRT/BT showed that freedom from relapse (FFR) was 57%, CSS was 62%, and OS was 57%. For the IMRT/3D-IGABT group, the 5-year results showed that FFR was 65% (P = .04), CSS was 69% (P = .01), and OS was 61% (P = .04). When stratified by lymph node status according to positron emission tomography scan results, disease control was most improved with IMRT/3D-IGABT versus 2D EBRT/BT in patients with positive pelvic lymph nodes only (P = .02). Cumulatively, 88 of 600 patients (15%) had grade ≥3 late bowel/bladder toxicity. The 2D EBRT/BT group had 55 patients (18%), and the IMRT/3D-IGABT group had 33 patients (11%; P = .02).

CONCLUSIONS

IMRT/3D-IGABT was associated with improved survival and decreased gastrointestinal and genitourinary toxicity in patients with cervical cancer compared with those who received 2D EBRT/BT.

Locally advanced cervical cancer: A study of 5-year outcomes

Background

Cervical cancer is the second most common cancer among Indian women. This present retrospective study was conducted to report patient outcomes with locally advanced cervical cancer treated in the year 2010.

Materials and Methods

Case records of cervical cancer patients registered from January 1, 2010, to December 31, 2010 were retrieved. A total of 1200 patients were registered, of which 583 received either definitive or adjuvant radiotherapy (RT). Of these, 345 patients who received complete treatment at our hospital were included for outcome analysis. Descriptive statistics were used to summarize patient- and treatment-related variables, and Kaplan-Meier analysis was performed for survival analysis.

Results

The median age was 56 years (range: 33-90). Squamous carcinoma was the most common histology (91.4%) and the majority were FIGO Stage III (45.4%). Median follow-up of the cohort was 44 months (1-85 months). The 5-year disease-free survival (DFS) across stages was 50%. Most important predictor of DFS was FIGO staging (Stage II vs. Stage III: 62% vs. 45%) and use of concurrent chemoradiotherapy (CTRT) l (RT vs. CTRT: 32% vs. 57%, respectively). Patients aged >70 years had a significantly poor DFS at 5 years; however, did not have any effect on survival. Grade 3 or more late toxicity was seen in only 5% of the patients.

Conclusion

Five-year DFS of 62% and 45% of Stage II and III patients treated under routine care represents comparable stage-matched results to the rest of the world, respectively.

CT Simulation to Evaluate of Pelvic Lymph Node Coverage in Conventional Radiotherapy Fields Based on Bone and Vessels Landmarks in Prostate Cancer Patients

BACKGROUND

Radiotherapy is the gold standard for treatment of prostrate cancer as it can cover an adequate area of tissues at risk for metastasis.

OBJECTIVES

We evaluated the Pelvic lymph node coverage of conventional radiotherapy fields based on bone and vessels landmarks using computed tomography (CT) simulation in patients with prostate cancer referred to Shohada-e-Tajrish hospital.

PATIENTS AND METHODS

In this cross sectional study, 40 patients with prostate cancer at the Stage T1c to T3b were studied. Pelvic lymph nodes were contoured by using pelvic vessels as surrogate markers. The distances were measured at different points of anterior-posterior (AP) and lateral fields and distances > 5 mm or more between the contoured nodes and the field borders.

RESULTS

Mean and standard deviation of the aortic bifurcation from the superior border was 4.73 ± 1.16 cm, the distance of common iliac bifurcation from the superior border was 1.11 ± 1.25 cm, the mean (SD) distance of right external iliac from the lateral border of AP field was 2.06 ± 0.48 cm and for left external iliac artery was 1.90 ± 0.56 cm. The distance of the external iliac artery from the anterior border of the lateral field was 2.30 ± 0.74 cm. The distance of the external iliac artery from pelvic rim was 0.59 ± 0.59 cm, distance of bifurcation of iliac from sacroiliac joint was 0.82 ± 1.01 cm, the size of the pelvic rim was 12.30 ± 0.64 cm, sacral width was 8.29 ± 1.01 cm, anterior promontory symphysis distance was 12.02 ± 0.92 cm and posterior promontory symphysis distance was 10.98 ± 0.73 cm.

CONCLUSIONS

We observed that conventional radiotherapy using CT simulation based on bone and vessels landmarks provided adequate coverage of pelvic lymph nodes in our patients with prostate cancer.

Pelvic nodal CTV from L4-L5 or aortic bifurcation? An audit of the patterns of regional failures in cervical cancer patients treated with pelvic radiotherapy

OBJECTIVE

To assess the patterns of recurrence in cervical cancer patients treated with pelvic nodal clinical target volume at L4-L5 junction instead of aortic bifurcation.

METHODS

Records of patients with locally advanced cervical cancer treated with chemo-radiation were reviewed. Patients treated with standard pelvic fields (superior border of the field at L4/L5 junction), without any radiological evidence of regional lymphadenopathy (<10 mm) were included in the study. The level of aortic bifurcation was retrospectively documented on computed tomography. Patterns of recurrences were correlated to the aortic bifurcation and the superior border of the radiation fields (L4/L5).

RESULTS

Aortic bifurcation was above the radiation fields (above L4/5) in 82 of 116 (70.7%) patients. Of the nine patients that recurred above the radiation field, 5 (55%) were above L4/5 failures, i.e. between aortic bifurcation and L4/5, and 4 (45%) had para-aortic failures. On retrospective analysis, 16 patients were found to have subcentimeter lymph nodes and higher nodal failures (7/16) were observed in patients with subcentimeter regional lymph nodes at diagnosis.

CONCLUSIONS

Superior border of nodal clinical target volume should ideally include the aortic bifurcation instead of L4-L5 inter space in patients with locally advanced cervical cancer. Radiotherapy fields need to be defined cautiously in patients with subcentimeter pelvic lymph nodes.

Dosimetric comparison between conventional and conformal radiotherapy for carcinoma cervix: Are we treating the right volumes?

Background and Purpose:

Conventional portals, based on bony anatomy, for external beam radiotherapy for cervical cancer have been repeatedly demonstrated as inadequate. Conversely, with image-based conformal radiotherapy, better target coverage may be offset by the greater toxicities and poorer compliance associated with treating larger volumes. This study was meant to dosimetrically compare conformal and conventional radiotherapy.

Materials and Methods:

Five patients of carcinoma cervix underwent planning CT scan with IV contrast and targets, and organs at risk (OAR) were contoured. Two sets of plans-conventional and conformal were generated for each patient. Field sizes were recorded, and dose volume histograms of both sets of plans were generated and compared on the basis of target coverage and OAR sparing.

Results:

Target coverage was significantly improved with conformal plans though field sizes required were significantly larger. On the other hand, dose homogeneity was not significantly improved. Doses to the OARs (rectum, urinary bladder, and small bowel) were not significantly different across the 2 arms.

Conclusion:

Three-dimensional conformal radiotherapy gives significantly better target coverage, which may translate into better local control and survival. On the other hand, it also requires significantly larger field sizes though doses to the OARs are not significantly increased.

Atlas-based segmentation improves consistency and decreases time required for contouring postoperative endometrial cancer nodal volumes

PURPOSE

Accurate target delineation of the nodal volumes is essential for three-dimensional conformal and intensity-modulated radiotherapy planning for endometrial cancer adjuvant therapy. We hypothesized that atlas-based segmentation ("autocontouring") would lead to time savings and more consistent contours among physicians.

METHODS AND MATERIALS

A reference anatomy atlas was constructed using the data from 15 postoperative endometrial cancer patients by contouring the pelvic nodal clinical target volume on the simulation computed tomography scan according to the Radiation Therapy Oncology Group 0418 trial using commercially available software. On the simulation computed tomography scans from 10 additional endometrial cancer patients, the nodal clinical target volume autocontours were generated. Three radiation oncologists corrected the autocontours and delineated the manual nodal contours under timed conditions while unaware of the other contours. The time difference was determined, and the overlap of the contours was calculated using Dice's coefficient.

RESULTS

For all physicians, manual contouring of the pelvic nodal target volumes and editing the autocontours required a mean±standard deviation of 32±9 vs. 23±7 minutes, respectively (p=.000001), a 26% time savings. For each physician, the time required to delineate the manual contours vs. correcting the autocontours was 30±3 vs. 21±5 min (p=.003), 39±12 vs. 30±5 min (p=.055), and 29±5 vs. 20±5 min (p=.0002). The mean overlap increased from manual contouring (0.77) to correcting the autocontours (0.79; p=.038).

CONCLUSION

The results of our study have shown that autocontouring leads to increased consistency and time savings when contouring the nodal target volumes for adjuvant treatment of endometrial cancer, although the autocontours still required careful editing to ensure that the lymph nodes at risk of recurrence are properly included in the target volume.

[Endometrial cancer]

Endometrial cancers are frequent and affect mainly postmenopausal women. They are mostly diagnosed at an early stage with an excellent prognosis. Surgery is the reference for a precise FIGO staging who guide adjuvant treatment. Tumor extension, grade, myometrium invasion and involved lymph nodes will be discriminating in therapeutic strategy. The management of stages I and II has been recently amended by ESMO, who proposed surveillance, brachytherapy, and radiation therapy followed by brachytherapy for respectively low, intermediate and high risk groups. These recommendations are controversial and must be confirmed. Locally advanced stages represent a heterogeneous population in which surgery should be proposed if it is feasible then followed by radiotherapy and/or chemotherapy. Based on an illustrated clinical case, indications, delineation, dosimetry and complications expected with radiotherapy are demonstrated.

Assessment of nodal target definition and dosimetry using three different techniques: implications for re-defining the optimal pelvic field in endometrial cancer

Purposes

1. To determine the optimal pelvic nodal clinical target volume for post-operative treatment of endometrial cancer. 2. To compare the DVH of different treatment planning techniques applied to this new CTV and the surrounding tissues.

Methods and Materials

Based on the literature, we selected a methodology to delineate nodal target volume to define a NEW-CTV and NEW-PTV. Conventional 2D fields, 3D fields based on anatomic guidelines per RTOG 0418, 3D fields based on our guidelines, and IMRT based on our guidelines were assessed for coverage of NEW-CTV, NEW-PTV, and surrounding structures. CT scans of 10 patients with gynecologic malignancies after TAH/BSO were used. DVHs were compared.

Results

For NEW-PTV, mean V45Gy were 50% and 69% for 2D and RTOG 0418-3DCRT vs. 98% and 97% for NEW-3DCRT and NEW-IMRT (p < 0.0009). Mean V45Gy small bowel were 24% and 20% for 2D and RTOG 0418-3DCRT, increased to 32% with NEW-3DCRT, and decreased to 14% with IMRT (p = 0.005, 0.138, 0.002). Mean V45Gy rectum were 26%, 35%, and 52% for 2D, RTOG 0418-3DCRT, and NEW-3DCRT, and decreased to 26% with NEW-IMRT (p < 0.05). Mean V45Gy bladder were 83%, 51%, and 73% for 2D, RTOG 0418-3DCRT, and NEW-3DCRT, and decreased to 30% with NEW-IMRT (p < 0.002).

Conclusions

Conventional 2D and RTOG 0418-based 3DCRT plans cover only a fraction of our comprehensive PTV. A 3DCRT plan covers this PTV with high doses to normal tissues, whereas IMRT covers the PTV while delivering lower normal tissue doses. Re-consideration of what specifically the pelvic target encompasses is warranted.

Evaluation of pelvic lymph node coverage of conventional radiotherapy fields based on bony landmarks in Chinese cervical cancer patients using CT simulation

OBJECTIVE

To evaluate the pelvic lymph node coverage of conventional pelvic fields based on bony landmarks in Chinese patients with cervical cancer by using computed tomography (CT) simulation images to contour pelvic vessels as substitutes for lymph nodes location.

METHODS

A retrospective review of CT simulation images and conventional pelvic radiation planning data sets was performed in 100 patients with cervical cancer at the International Federation of Gynecology and Obstetrics (FIGO) Stage IIB to IIIB in our hospital. Pelvic arteries were contoured on CT simulation images, and the outlines of conventional pelvic fields were drawn as defined by the gynecologic oncology group (GOG) after hiding the contours. The distances between the following vessel contours and field borders were measured: D(1), the superior border of the anterior/posterior (AP) field and the bifurcation of abdominal aorta; D(2), the ipsilateral border of the AP field and the distal end of external iliac artery; and D(3), the anterior border of the lateral (LAT) field and the distal end of the external iliac artery. The distances were recorded as positive values if the measuring point was within the conventional pelvic fields, or they were recorded as negative values. Lymph nodes coverage was considered adequate when D(1)(0 mm, D(2)(17 mm or D(3)(7 mm.

RESULTS

All patients had at least 1 inadequate margin, 97 patients (97.0%) had 2, and 22 patients (22.0%) had all the 3. On the AP field, 95 patients (95%) had the measuring point, the bifurcation of the abdominal aorta, out of the field (D(1)<0 mm), and all the patients had a distance less than 17.0 mm between the distal end of the external iliac artery and ipsilateral border (D(2)<17.0 mm). On the LAT field, 24 patients (24%) had a distance less than 7.0 mm between the distal end of the external iliac artery and anterior border (D(3)<7.0 mm).

CONCLUSION

We observed that conventional pelvic fields based on bony landmarks provided inadequate coverage of pelvic lymph nodes in our patients with cervical cancer. CT simulation may be a feasible technique for planning pelvic fields optimally and individually.

Consensus guidelines for delineation of clinical target volume for intensity-modulated pelvic radiotherapy in postoperative treatment of endometrial and cervical cancer

PURPOSE

To develop an atlas of the clinical target volume (CTV) definitions for postoperative radiotherapy of endometrial and cervical cancer to be used for planning pelvic intensity-modulated radiotherapy.

METHODS AND MATERIALS

The Radiation Therapy Oncology Group led an international collaboration of cooperative groups in the development of the atlas. The groups included the Radiation Therapy Oncology Group, Gynecologic Oncology Group, National Cancer Institute of Canada, European Society of Therapeutic Radiology and Oncology, and American College of Radiology Imaging Network. The members of the group were asked by questionnaire to define the areas that were to be included in the CTV and to outline theses areas on individual computed tomography images. The initial formulation of the group began in late 2004 and culminated with a formal consensus conference in June 2005.

RESULTS

The committee achieved a consensus CTV definition for postoperative therapy for endometrial and cervical cancer. The CTV should include the common, external, and internal iliac lymph node regions. The upper 3.0 cm of the vagina and paravaginal soft tissue lateral to the vagina should also be included. For patients with cervical cancer, or endometrial cancer with cervical stromal invasion, it is also recommended that the CTV include the presacral lymph node region.

CONCLUSION

This report serves as an international template for the definition of the CTV for postoperative intensity-modulated radiotherapy for endometrial and cervical cancer.

Postoperative Irradiation of Gynecologic Malignancies: Improving Treatment Delivery Using Aperture-Based Intensity-Modulated Radiotherapy

PURPOSE

To evaluate dosimetric and treatment delivery advantages of aperture-based intensity-modulated radiotherapy (AB-IMRT) for the treatment of patients receiving whole pelvic radiotherapy for gynecologic malignancies.

METHODS AND MATERIALS

Nineteen patients undergoing pelvic radiotherapy after resection of endometrial cancers were selected. A 45-Gy dose was prescribed to the target volume delineated on a planning CT scan. An in-house inverse planning system, Ballista, was used to develop a treatment plan using aperture-based multileaf collimator segments. This approach was compared with conventional four-field, enlarged four-field, and static beamlet-based IMRT (BB-IMRT) techniques in terms of target coverage, dose-volume histogram statistics for surrounding normal tissues, and numbers of segments and monitor units (MU).

RESULTS

Three quarters (76.4%) of the planning target volume received the prescription dose with conventional four-field plans. With adequate target coverage, the Ballista plans significantly reduced the volume of bowel and bladder irradiated at the prescribed dose (p < 0.001), whereas the two approaches provided equivalent results for the rectum (p = 0.5). On the other hand, AB-IMRT and BB-IMRT plans showed only small differences in dose-volume histogram statistics of unknown clinical impact, whereas Ballista plan delivery required on average 73% and 59% fewer segments and MU, respectively.

CONCLUSION

With respect to conventional techniques, AB-IMRT for the treatment of gynecologic malignancies provides dosimetric advantages similar to those with BB-IMRT but with clear treatment delivery improvements.