Variability in target delineation of cervical carcinoma: A Korean radiation oncology group study (KROG 15-06)

Enhancing quality assurance in radiotherapy for gynaecological cancers: implementation of an on-demand peer review process

OBJECTIVES

Ensuring high-quality radiotherapy requires peer-reviewing target volumes. The Royal College of Radiologists recommends peer review specifically for individual target volumes in cases of gynaecological cancers. This study presents the outcomes of implementing an on-demand peer review system for gynaecological cancers within our institute.

METHODS

The peer review process was planned for gynaecological cancer cases intended for curative radiotherapy. After junior clinical oncologists (COs) completed the segmentation, two senior COs specializing in gynaecological cancers conducted the peer review. All peer review outcomes were recorded prospectively. The audit process compliance, the proportion of patients requiring major and minor modifications in target volumes, the direction of changes, and the factors influencing these changes were reported.

RESULTS

A total of 230 patients were eligible, and out of these, 204 (88.3%) patients underwent at least one peer review. Among the patients, 108 required major modifications in their target volumes. P-charts revealed a stabilization in the need for major modifications at the end of three months, indicating that 38.2% and 28% of patients still required major modifications for the nodal and primary CTV, respectively. Multivariable analysis demonstrated that major modifications were associated with the use of extended field radiotherapy and radical radiation in non-cervical primary cases.

CONCLUSIONS

An on-demand peer review system was feasible and resulted in clinically meaningful, major modifications in the target volumes for 53% of patients.

ADVANCES IN KNOWLEDGE

Gynaecological cancers require ongoing peer review to ensure quality of care in radiotherapy. A flexible on-demand system not only ensures that patient treatment start is not delayed but also has an important educational role for junior trainees.

Inter-observer variation of target volume delineation for CT-guided cervical cancer brachytherapy

Purpose

Delineation is a critical and challenging step in radiotherapy planning. Differences in delineation among observers are common, despite the presence of contouring guidelines. This study aimed to identify the inter-observer variability in the target volume delineation of computed tomography (CT)-guided brachytherapy for cervical cancer.

Material and methods

Four radiation oncologists (ROs) with different expertise levels delineated high-risk (HR) and intermediate-risk (IR) clinical target volume (CTV) according to GYN GEC-ESTRO recommendations, in a blinded manner on every CT set of ten locally advanced cervical cancer cases. The most experienced RO's contours were determined as the index and used for comparison. Dice similarity coefficient (DSC) and pairwise Hausdorff distance (HD) metrics were applied to compare the overlap and gross deviations of all contours.

Results

Median DSC for HR-CTV and IR-CTV were 0.73 and 0.76, respectively, and a good concordance was achieved for both in majority of contours. While there was no difference in DSC measurements for HR-CTV among the three ROs, RO-3 provided improved DSC values for IR-CTV (p = 0.01). Median HD95 was 5.02 mm and 6.83 mm, and median HDave was 1.69 mm and 2.21 mm for HR-CTV and IR-CTV, respectively. There was no significant difference among ROs in HR-CTV for HD95 or HDave; however, IR-CTV value was significantly improved according to RO-3 (p = 0.01). Case-by-case HD analysis showed no significant inter-observer variations, except for two cases.

Conclusions

The inter-observer agreement is generally high for target volumes in CT-guided brachytherapy for cervical cancer. The agreement is lower for IR-CTV than HR-CTV. The individual characteristics of each case and different expertise levels of the ROs may have caused the differences. Despite the good concordance for delineation, dosimetric consequences can still be clinically significant.

Radiation Therapies in Cancer

A crucial element of cancer treatment is radiation therapy that is used to destroy tumors and cancer cells through radiation. Another essential component is immunotherapy that helps immune system to combat cancer. The combination of both radiation therapy and immunotherapy is being focused recently for the treatment of many tumors. Chemotherapy includes the use of some chemical agent to control the growth of cancer, whereas irradiation involves the use of radiations of high energy to kill cancer cells. The union of both became the strongest practice in cancer treatment techniques. Specific chemotherapies are combined with radiation in the treatment of cancer after proper preclinical assessment of their effectiveness. Some classes of compounds include platinum-based drugs, antimicrotubules, antimetabolites (5-Fluorouracil, Capecitabine, Gemcitabine, Pemetrexed), topoisomerase I inhibitors, alkylating agents (Temozolomide), and other agents (Mitomycin-C, Hypoxic Sensitizers, Nimorazole).

[Usefulness of Metal Artifact-reduced Reconstruction for Image-guided Brachytherapy for Cervical Cancer]

PURPOSE

To evaluate the usefulness of single-energy metal artifact reduction (SEMAR) for target delineation in brachytherapy for cervical cancer patients with metal hip implants.

MATERIAL AND METHODS

A series of four definitive brachytherapy sessions in the same patient was analyzed. At each brachytherapy session, the identical set of computed tomography images was subjected with or without SEMAR treatment. For both SEMAR-treated and -untreated sets, five radiation oncologists delineated the high-risk clinical target volume (HR-CTV), bladder, and rectum, for which the volume, Dice coefficient, and the dose volume parameters were compared between SEMAR-treated and -untreated datasets.

RESULTS

The bladder volume was significantly greater in the SEMAR-treated datasets compared with the SEMAR-untreated datasets. Importantly, for the bladder, Dice coefficient among five radiation oncologists was significantly higher for the SEMAR-treated datasets compared with the SEMAR-untreated datasets. These effects of SEMAR treatment were not evident for HR-CTV and the rectum.

CONCLUSIONS

These data indicate that SEMAR treatment contributes to improve delineation of the bladder in brachytherapy for cervical cancer patients with metal hip implants.

A dummy-run evaluation of postoperative hypofractionated intensity-modulated radiation therapy (POHIM-RT) trials for cervical cancer

The postoperative hypofractionated intensity-modulated radiation therapy (POHIM-RT) trial is a phase II study to evaluate toxicity following hypofractionated intensity modulated radiation therapy (IMRT) for cervical cancer. This study describes the results of a benchmark procedure for RT quality assurance of the POHIM-RT trial. Six participating institutions were provided computed tomography for RT planning and an IMRT plan for a sample and were instructed to delineate volumes, create a treatment plan and quality assurance (QA) plan, and submit the results of all procedures. The inter-institutional agreements on RT volume and plan results were evaluated using the kappa value and dice similarity coefficients. The simultaneous truth and performance level estimation (STAPLE) method was employed to generate a consensus target volume. The treatment volumes, organs-at-risk volumes, and results of the RT plan and QA reported by the institutions were acceptable and adhered well to the protocol. In terms of clinical target volume (CTV) delineation, there were differences between the institutions, particularly in vaginal cuff and paracolpium subsites. Consensus CTV was generated from the collected CTVs with the STAPLE method. The participating institutions showed considerable agreement regarding volume, dose and QA results. To improve CTV agreement in CTV, we provided feedback with images of the consensus target volume and detailed written guidelines for specific subsites that were the most heterogeneous.

Patterns of definitive radiotherapy practice for cervical cancer in South Korea: a survey endorsed by the Korean Radiation Oncology Group (KROG 20-06)

Objective

The Korean Radiation Oncology Group conducted a nationwide questionnaire survey to evaluate the patterns of clinical practice for patients with cervical cancer receiving definitive radiation therapy (RT) in South Korea.

Methods

Practicing radiation oncologists from 93 centers in South Korea were administered a questionnaire survey via e-mail. The survey focused on demographic characteristics, diagnostic evaluation, indications for definitive RT, RT techniques, RT field and dose prescription, lymph node (LN) boost RT, brachytherapy, and chemotherapy.

Results

The response rate was 62.4% (58/93 institutions). Of the 2,134 patients treated at the radiation oncology department in 2019, 48.8% underwent definitive RT. The selection of patients for definitive concurrent chemoradiation therapy and RT field, and RT dose prescription varied greatly. The upper border of the pelvis was commonly used as the bony landmark for external beam RT (81%–88% of respondents). Most (96.6%) centers performed LN boost RT with median total doses of 59 Gy and 59.2 Gy for pelvic and retroperitoneal LN, respectively. With 50% of the centers offering brachytherapy, image-guided brachytherapy and volume-based prescription were applied in 48.3% and 37.9%, respectively. Upfront concurrent chemoradiation therapy with varying prescription doses was considered by 60.4% respondents in cases of supraclavicular LN metastasis.

Conclusion

Most differences were noted in the indications for treatment, RT field, and prescription dose. This finding can serve as a reference for establishing practical RT guidelines for the management of locally advanced cervical cancer.