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Clinical outcomes in cervical cancer patients treated by FDG-PET/CT-based 3-dimensional planning for the first brachytherapy session

View Article: PubMed Central - PubMed

ABSTRACT

The aim of the study was to evaluate the treatment outcomes in cervical cancer patients treated with 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT)-guided 3-dimensional brachytherapy (3D-BT) planning for the first brachytherapy session.

We retrospectively analyzed 87 patients with cervical cancer who received definitive radiotherapy (RT). Primary tumor size was ≤4 cm in 22 patients (25.3%), >4 cm and ≤6 cm in 45 patients (51.7%), and >6 cm in 20 patients (23.0%). The median total dose of external beam RT was 50.4 (50.4–60.4) Gy. FDG-PET/CT-guided 3D-BT with an iridium-192 source was performed. The clinical target volume (CTV) for 3D-BT included the entire cervix and the abnormal FDG-uptake with a 1-cm expansion. A planned total dose was 24 Gy at 4 Gy per insertion 3 times per week using a tandem and 2 ovoids.

The mean D95 and D90 for the CTV were 73.4 (±5.9) Gy and 77.9 (±6.9) Gy, respectively (EQD2, α/β=10). The D2cc for the rectum and bladder was 374 (±97.4) cGy and 394 (±107.6) cGy per fraction, respectively. The EQD2 (α/β=3) for the D2cc was 74.5 (±12.4) Gy for the rectum and 77.3 (±14.6) Gy for the bladder. The median follow-up period was 40 (8–61) months. The 3-year overall survival (OS), progression-free survival (PFS), and local control (LC) rates were 84.7%, 72.1%, and 89.2%, respectively. The 3-year LC rate was 100% for tumors ≤ 4 cm, 91.1% for tumors > 4 cm and ≤ 6 cm, and 70.5% for tumors > 6 cm (P = 0.014). Local failure developed in 9 patients. Three patients had local failures outside of the CTV. Grade 1, 2, and 3 rectal bleeding developed in 5, 4, and 2 patients, respectively. One patient experienced rectovaginal fistula.

FDG-PET/CT-guided 3D-BT planning is a feasible approach, which showed favorable clinical outcomes.

No MeSH data available.


Related in: MedlinePlus

Target volume delineation of FDG-PET/CT-guided 3-dimensional brachytherapy (gross tumor volume: orange; clinical target volume: sky blue; bladder: yellow; rectum: green). CT = computed tomography, FDG = 18F-fluorodeoxyglucose, PET = positron emission tomography.
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Figure 1: Target volume delineation of FDG-PET/CT-guided 3-dimensional brachytherapy (gross tumor volume: orange; clinical target volume: sky blue; bladder: yellow; rectum: green). CT = computed tomography, FDG = 18F-fluorodeoxyglucose, PET = positron emission tomography.

Mentions: The PET and CT data were transferred to an EBRT treatment planning system (TPS) (Pinnacle V6.5, Philips, Madison, WI) for the delineation of the target volume and OARs (i.e., the rectum and bladder). Complete response (no residual tumor) on the PET/CT is defined as resolution of FDG uptake within the tumor volume so that is indistinguishable from surrounding normal tissue, and which was determined by a nuclear medicine physician and a radiation oncologist. For partially responded tumor, the gross tumor volume (GTV) was delineated. In our protocol, the determination of the GTV outline was based on the threshold value of 40% of the SUVmax within a region of interest encompassing the tumor, and it was adjusted by physician. Our previous data [12] showed that contouring by simple visual analysis resulted in a median threshold value of 41% of the SUVmax. The clinical target volume (CTV) included the entire cervix and the GTV with a 1-cm expansion in the direction of the initial extension of the tumor considering the clinically suspected lesion or uncertainty of PET/CT imaging (i.e., into the vagina or uterine body and the side of parametrial extension considering anatomic boundaries; Fig. 1). If the PET/CT image showed a metabolic complete response, the CTV included the entire cervix. For the treatment planning, the CTV and the OARs were transferred to a brachytherapy TPS (PLATO, version 14.3, Nucletron, Netherlands). Three-dimensional planning was performed using the optimization tool of the brachytherapy TPS, and manual modifications of the loading pattern and the dwell time were performed by referencing the dose–volume histogram of the target and OARs. We aimed to optimize the plan so that the minimum dose received by 95% of the volume (D95) was greater than the prescribed dose, whereas 2 cm3 of the volume (D2cc) of the OARs received less than the prescribed dose.


Clinical outcomes in cervical cancer patients treated by FDG-PET/CT-based 3-dimensional planning for the first brachytherapy session
Target volume delineation of FDG-PET/CT-guided 3-dimensional brachytherapy (gross tumor volume: orange; clinical target volume: sky blue; bladder: yellow; rectum: green). CT = computed tomography, FDG = 18F-fluorodeoxyglucose, PET = positron emission tomography.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4998314&req=5

Figure 1: Target volume delineation of FDG-PET/CT-guided 3-dimensional brachytherapy (gross tumor volume: orange; clinical target volume: sky blue; bladder: yellow; rectum: green). CT = computed tomography, FDG = 18F-fluorodeoxyglucose, PET = positron emission tomography.
Mentions: The PET and CT data were transferred to an EBRT treatment planning system (TPS) (Pinnacle V6.5, Philips, Madison, WI) for the delineation of the target volume and OARs (i.e., the rectum and bladder). Complete response (no residual tumor) on the PET/CT is defined as resolution of FDG uptake within the tumor volume so that is indistinguishable from surrounding normal tissue, and which was determined by a nuclear medicine physician and a radiation oncologist. For partially responded tumor, the gross tumor volume (GTV) was delineated. In our protocol, the determination of the GTV outline was based on the threshold value of 40% of the SUVmax within a region of interest encompassing the tumor, and it was adjusted by physician. Our previous data [12] showed that contouring by simple visual analysis resulted in a median threshold value of 41% of the SUVmax. The clinical target volume (CTV) included the entire cervix and the GTV with a 1-cm expansion in the direction of the initial extension of the tumor considering the clinically suspected lesion or uncertainty of PET/CT imaging (i.e., into the vagina or uterine body and the side of parametrial extension considering anatomic boundaries; Fig. 1). If the PET/CT image showed a metabolic complete response, the CTV included the entire cervix. For the treatment planning, the CTV and the OARs were transferred to a brachytherapy TPS (PLATO, version 14.3, Nucletron, Netherlands). Three-dimensional planning was performed using the optimization tool of the brachytherapy TPS, and manual modifications of the loading pattern and the dwell time were performed by referencing the dose–volume histogram of the target and OARs. We aimed to optimize the plan so that the minimum dose received by 95% of the volume (D95) was greater than the prescribed dose, whereas 2 cm3 of the volume (D2cc) of the OARs received less than the prescribed dose.

View Article: PubMed Central - PubMed

ABSTRACT

The aim of the study was to evaluate the treatment outcomes in cervical cancer patients treated with 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT)-guided 3-dimensional brachytherapy (3D-BT) planning for the first brachytherapy session.

We retrospectively analyzed 87 patients with cervical cancer who received definitive radiotherapy (RT). Primary tumor size was ≤4 cm in 22 patients (25.3%), >4 cm and ≤6 cm in 45 patients (51.7%), and >6 cm in 20 patients (23.0%). The median total dose of external beam RT was 50.4 (50.4–60.4) Gy. FDG-PET/CT-guided 3D-BT with an iridium-192 source was performed. The clinical target volume (CTV) for 3D-BT included the entire cervix and the abnormal FDG-uptake with a 1-cm expansion. A planned total dose was 24 Gy at 4 Gy per insertion 3 times per week using a tandem and 2 ovoids.

The mean D95 and D90 for the CTV were 73.4 (±5.9) Gy and 77.9 (±6.9) Gy, respectively (EQD2, α/β=10). The D2cc for the rectum and bladder was 374 (±97.4) cGy and 394 (±107.6) cGy per fraction, respectively. The EQD2 (α/β=3) for the D2cc was 74.5 (±12.4) Gy for the rectum and 77.3 (±14.6) Gy for the bladder. The median follow-up period was 40 (8–61) months. The 3-year overall survival (OS), progression-free survival (PFS), and local control (LC) rates were 84.7%, 72.1%, and 89.2%, respectively. The 3-year LC rate was 100% for tumors ≤ 4 cm, 91.1% for tumors > 4 cm and ≤ 6 cm, and 70.5% for tumors > 6 cm (P = 0.014). Local failure developed in 9 patients. Three patients had local failures outside of the CTV. Grade 1, 2, and 3 rectal bleeding developed in 5, 4, and 2 patients, respectively. One patient experienced rectovaginal fistula.

FDG-PET/CT-guided 3D-BT planning is a feasible approach, which showed favorable clinical outcomes.

No MeSH data available.


Related in: MedlinePlus