Patterns of failure after use of (18)F-FDG PET/CT in integration of extended-field chemo-IMRT and 3D-brachytherapy plannings for advanced cervical cancers with extensive lymph node metastases

[18F]FDG-PET-Based Personalized Radiotherapy Dose Prescription

PET imaging with 2'-deoxy-2'-[18F]fluoro-D-glucose ([18F]FDG) has become one of the pillars in the management of malignant diseases. It has proven value in diagnostic workup, treatment policy, follow-up, and as prognosticator for outcome. [18F]FDG is widely available and standards have been developed for PET acquisition protocols and quantitative analyses. More recently, [18F]FDG-PET is also starting to be appreciated as a decision aid for treatment personalization. This review focuses on the potential of [18F]FDG-PET for individualized radiotherapy dose prescription. This includes dose painting, gradient dose prescription, and [18F]FDG-PET guided response-adapted dose prescription. The current status, progress, and future expectations of these developments for various tumor types are discussed.

Oncologic outcomes in the era of modern radiation therapy using FIGO 2018 staging system for cervical cancer

BACKGROUND

The recently published ASTRO cervical cancer guidelines recommend the use of modern radiotherapy. Imaging is now incorporated in the updated FIGO 2018 staging with a new stage IIIC. This study aims to evaluate the oncologic outcomes and predictors of survival using FIGO 2018 staging in a cohort of patients treated in an era of high-precision image-guided radiotherapy.

METHODS

We performed a retrospective cohort study of 216 adult cervical cancer patients treated with definitive chemoradiotherapy between 2010 and 2018. Eligible patients had non-metastatic cervical cancer treated at a single academic institution. All patients had pre-treatment MRI and CT/PET. Treatment protocol consisted of external beam intensity-modulated radiotherapy and 3D image-guided brachytherapy. Kaplan-Meier curves were used for survival analysis. Multivariate cox proportional-hazards model was performed to identify potential prognostic factors.

RESULTS

Median age at diagnosis was 50 and median BMI was 26.4 kg/m². Median follow-up time was 44.3 months. Five-year overall survival (OS), disease-free survival and loco-regional disease-free survival rates were 76.8%, 68.5% and 82.6%, respectively. FIGO 2018 showed better OS discrimination compared to FIGO 2009 classification. OS was increasingly worse with positive pelvic and para-aortic nodes (p < 0.001). In a multivariate prediction model, performance status (p = 0.044) and FIGO 2018 classification (stage III p = 0.016; stage IVA p = 0.010) were predictors of mortality; FIGO 2018 classification (stage III p = 0.003; stage IVA p = 0.001) was a predictor of any recurrence; MRI tumor diameter (p ≤ 0.001) and nodal metastases (p = 0.024) were predictors of loco-regional recurrence.

CONCLUSIONS

Integration of state-of-the-art imaging in cervical cancer staging and in radiotherapy planning leads to good loco-regional control rates, however distant recurrence remains an important issue. FIGO 2018 staging better reflects patient prognosis, highlighting the need for new treatment strategies for stage IIIC cervical cancer.

Nodal recurrence patterns on PET/CT after RTOG-based nodal radiotherapy for prostate cancer

•

Recurrence patterns on PET/CT after RT for PC_N+ were correlated with nodal fields.

•

In-field nodal recurrences were uncommon.

•

Out-field nodal recurrences occurred mostly just above the elective nodal field.

•

Expanding elective fields to the aorta bifurcation may prolong disease-free survival.

Purpose

Biochemical failure after external beam radiotherapy (RT) for node-positive prostate cancer (PC_N+) frequently involves nodal recurrences, in most cases out of field. This raises the question if current RTOG-based elective nodal fields can still be considered optimal. Modern diagnostic tools like PSMA PET/CT and choline PET/CT can visualize nodal recurrences with unprecedented accuracy. We evaluated recurrence patterns on PET/CT after RT for PC_N+, with the aim to explore options for improved nodal target definition.

Methods and materials

Data of all patients treated with curative intent EBRT for PC_N+ in NKI-AVL from 2008 to 2018 were retrospectively reviewed. EBRT comprised 70 Gy to the prostate or 66–70 Gy to the prostate bed, 60 Gy to involved nodes, and 52,5–56 Gy (46 Gy EQD2) to RTOG-based elective nodal fields, in 35 fractions. Locations of recurrences on PET/CT were noted, and nodal locations were correlated with the applied EBRT fields.

Results

42 patients received PSMA (28) or choline (14) PET/CT at biochemical recurrence. 35 patients (83%) had a positive scan. At their first positive scan 17 patients had nodal metastasis, in some cases together with a local recurrence or distant disease. In-field nodal recurrences were uncommon (n = 3). Out-field nodal recurrences occurred more frequently (n = 14), with the majority (n = 12) just above the elective nodal field. These nodes were the single area of detectable failure in 6 patients (14%).

Conclusions

Current RT with RTOG-based nodal fields for PC_N+ provides good in-field tumour control, but frequent out-field nodal recurrences suggest missed microscopic locations. Expanding elective fields to include the aorta bifurcation may prolong recurrence-free survival. Future research must address whether the potential benefits of this strategy outbalance additional toxicity.

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.

Evaluating the Use of 18F-FDG PET CT for External Beam Radiotherapy Planning in Gynaecological Malignancies

PURPOSE OF REVIEW

To evaluate the evidence for the use of fluorine-18-fluorodeoyglucose (18F-FDG) PET CT in external beam radiotherapy planning for treatment of gynaecological malignancies.

RECENT FINDINGS

Our review confirms that the incorporation of 18F-FDG PET CT during radiotherapy planning may decrease inter-observer variability during target delineation. It can also provide useful functional information regarding the tumour, which may facilitate the development of techniques for dose escalation and 'dose painting' not only for primary disease, especially in cervical cancer, but also nodal metastasis. The utilisation of this functional modality in external beam radiotherapy planning, particularly in locally advanced cervical malignancy, is an exciting topic that warrants further prospective research. Perhaps the most valuable role may be the potential to deliver dose escalation to 18F-FDG PET CT avid targets previously limited by organ at risk constraints, now that we have significantly more advanced radiotherapy planning tools at our disposal.

[18F]-2-Fluoro-2-Deoxy-D-glucose-PET Assessment of Cervical Cancer

This article provides an overview of PET in cervical cancer, primarily with regard to the use of ¹⁸F-2-fluoro-2-deoxy-d-glucose-PET/computed tomography. A brief discussion of upcoming technologies, such as PET/MR imaging, is presented.

CTV to PTV in cervical cancer: From static margins to adaptive radiotherapy

Intensity-modulated radiotherapy (IMRT) is increasingly used in order to minimize the gastrointestinal, genitourinary, and hematological toxicity in cervical and uterine cancers. However, the benefit of this high-precision approach is detracted by the margins applied to the clinical target volume (CTV) to generate the planning tumor volume (PTV), taking into account tumor and surrounding organs movements, deformations, and volume changes. Adequate PTV margins should be large enough to prevent geographical misses, but not excessive, which might end the benefit from IMRT. The objectives of this review were: (a) to present the evidence available for the determination of CTV-PTV margin for uterine cancers; (b) to highlight the impact of these margins in the context of adaptive radiotherapy; and (c) to discuss the role of the PTV concept in intracavitary brachytherapy.