Trends and variation in the use of radiotherapy in non-metastatic prostate cancer: A 12-year nationwide overview from the Netherlands.

PURPOSE: This population-based study describes nationwide trends and variation in the use of primary radiotherapy for non-metastatic prostate cancer in The Netherlands in 2008-2019. METHODS: Prostate cancer patients were selected from the Netherlands Cancer Registry (N = 103,059). Treatment trends were studied over time by prognostic risk groups. Multilevel analyses were applied to identify variables associated with external beam radiotherapy (EBRT) and brachy-monotherapy versus no active treatment in low-risk disease, and EBRT versus radical prostatectomy in intermediate and high-risk disease. RESULTS: EBRT use remained stable (5-6%) in low-risk prostate cancer and increased from 21% to 32% in intermediate-risk, 37% to 45% in high-risk localized and 50% to 57% in high-risk locally advanced disease. Brachy-monotherapy decreased from 19% to 6% and from 15% to 10% in low and intermediate-risk disease, respectively, coinciding an increase of no active treatment from 55% to 73% in low-risk disease. Use of EBRT or brachy-monotherapy versus no active treatment in low-risk disease differed by region, T-stage and patient characteristics. Hospital characteristics were not associated with treatment in low-risk disease, except for availability of brachy-monotherapy in 2008-2013. Age, number of comorbidities, travel time for EBRT, prognostic risk group, and hospital characteristics were associated with EBRT versus prostatectomy in intermediate and high-risk disease. CONCLUSION: Intermediate/high-risk PCa was increasingly managed with EBRT, while brachy-monotherapy in low/intermediate-risk PCa decreased. In low-risk PCa, the no active treatment-approach increased. Variation in treatment suggests treatment decision related to patient/disease characteristics. In intermediate/high-risk disease, variation seems furthermore related to the treatment modalities available in the diagnosing hospitals.

Impact of a fiducial marker based ART strategy on margins in postoperative IMRT of gynecological tumors.

PURPOSE: To investigate the potential of an offline Adaptive Radiotherapy (ART) strategy, based on the interfractional vagina motion (IVM) measured using fiducial markers (FM) during an initial number of fractions, on the CTV to PTV margins in post-operative gynecological patients. MATERIALS AND METHODS: In 18 patients, treated post-operatively for gynecological tumors, the systematic residual IVM was quantified after simulating an offline ART procedure, utilizing the average IVM measured with FM for a varying initial numbers of fractions to find the optimal moment to adapt the treatment plan and a threshold for selecting patients for replanning. Clinical margins for a zero, 2 and 5 mm threshold based strategy were calculated to assess the possible margin reduction. RESULTS: Applying an ART strategy based on the average IVM of the initial 5 fractions reduces the systematic IVM significantly (P < 0.025), allowing a reduction of the clinical margin of 3 mm (20%) in the CC direction and 2 mm (13%) in the AP direction. A 2 mm threshold for selecting patients for replanning shows no difference in the reduction of the clinical margin, but reduces the workload with 12%. CONCLUSION: An ART strategy based on adapting on the average IVM during the initial 5 fractions of treatment provides an opportunity to reduce the CTV to PTV margins in postoperative gynecological tumors. To keep the workload in balance with the best achievable margin reduction, a threshold for selecting patients for plan adaptation is recommended.

Prediction of optimal needle configuration in the first fraction of cervix brachytherapy.

BACKGROUND AND PURPOSE: Applying needles in the first brachytherapy (BT) fraction for patients with locally advanced cervical cancer allows for more dose conformality and OAR sparing, but is more challenging than in subsequent fractions, as pre-implant imaging with applicator in situ is lacking. We investigate whether a needle simulation, a fixed needle configuration or a multidisciplinary discussion-based configuration can predict more accurately which applicator needle positions are best suited for use in the first BT fraction. MATERIALS AND METHODS: For 20 patients we retrospectively determined the "reference" needle configuration (RC) for the first BT fraction using magnetic resonance imaging (MRI) scans with applicator in situ. We simulated a pre-MRI needle configuration (PC) using the MRI made in the fourth week of external beam radiotherapy (EBRT) without applicator in situ. We generated a fixed needle configuration (FC) from the most common RC needles. Using Dice's similarity coefficient (DSC) we compared each of these needle configurations, including the clinically applied "multidisciplinary consensus" needle configuration (MC), with RC. We considered two scenarios: allowing up to ten needles (scenario 1), and limiting the needle number (scenario 2). The analysis was repeated omitting two mid-ventral needles previously determined as non-essential to treatment planning. RESULTS: For both scenarios, the median DSC for PC and FC was higher than for MC (scenario1:DSCPC = 0,78; DSCFC = 0,75; DSCMC = 0,57; scenario 2:DSCPC = 0,74; DSCFC = 0,73; DSCMC = 0,59), while omitting mid-ventral needles resulted in no statistically significant differences in DSC. CONCLUSIONS: The PC or FC method are at least as accurate as the MC, with the FC preferred for efficiency.

Needle use and dosimetric evaluation in cervical cancer brachytherapy using the Utrecht applicator.

BACKGROUND AND PURPOSE: To analyse the clinical use of needles and examine the feasibility to meet the planning criteria in three fractions of cervical cancer brachytherapy. Furthermore, to investigate whether the needles with the largest discrepancy between application and loading are essential to treatment planning. MATERIALS AND METHODS: For 22 patients we analysed the applied and loaded needle patterns, and examined the dosimetric results for small (<30 cm3) and large (≥30 cm3) CTVHR. We removed from the clinical plans (CP) the needles applied most, but with the lowest loading frequency and intensity and re-optimized these plans (RP). RESULTS: On average 5.8 needles were applied and 4.8 loaded per fraction, with average intensity 22% (17% for small, 29% for large CTVHR). Mid-lateral needles were applied and loaded most frequently and intensely. The average CTVHR D90% prescribed dose was 88.8 Gy (SD 4.2) EQD210, the average OAR [Formula: see text] limit was respected. Omitting the mid-ventral needles, minimal statistically significant differences were found in dose distributions between RP and CP. CONCLUSIONS: Applying on average 5.8 needles per fraction it was possible to meet the planning criteria for targets and OARs in three BT fractions for both small and large CTVHR. The mid-ventral needles were not essential in treatment planning, unless situated in the vicinity of the GTVres.

A dosimetric evaluation of dose escalation for the radical treatment of locally advanced vulvar cancer by intensity-modulated radiation therapy.

The purpose of this planning study was to determine whether intensity-modulated radiation therapy (IMRT) reduces the radiation dose to organs at risk (OAR) when compared with 3D conventional radiation therapy (3D-CRT) in patients with vulvar cancer treated by irradiation. This study also investigated the use of sequential IMRT boost (seq-IMRT) and simultaneous integrated boost (SIB-IMRT) for dose escalation in the treatment of locally advanced vulvar cancer. Five vulvar cancer patients treated in the postoperative setting and 5 patients treated with definitive intent (def-group) were evaluated. For the postoperative group, 3D-CRT and IMRT plans to a total dose (TD) of 45 Gy were generated. For the def-group, 4 plans were generated: a 3D-CRT and an IMRT plan to a TD of 56.4 Gy, a SIB-IMRT plan to a TD of 56 Gy, and a SIB-IMRT with dose escalation (SIB-IMRT-esc): TD of 67.2 Gy. Mean dose and dose-volume histograms were compared using Student's t-test. IMRT significantly (all p < 0.05) reduced the D(mean), V30, and V40 for all OAR in the adjuvant setting. The V45 was also significantly reduced for all OAR except the bladder. For patients treated in the def-group, all IMRT techniques significantly reduced the D(mean), V40, and V45 for all OAR. The mean femur doses with SIB-IMRT and SIB-IMRT-esc were 47% and 49% lower compared with 3D-CRT. SIB-IMRT-esc reduced the doses to the OAR compared with seq-3D-CRT but increased the D(max.) for the small bowel, rectum, and bladder. IMRT reduces the dose to the OAR compared with 3D-CRT in patients with vulvar cancer receiving irradiation to a volume covering the vulvar region and nodal areas without compromising the dosimetric coverage of the target volume. IMRT for vulvar cancer is feasible and an attractive option for dose escalation studies.