Dosimetric impact of bone marrow sparing for robustly optimized IMPT for locally advanced cervical cancer

BACKGROUND AND PURPOSE

To investigate the trade-off between bone marrow sparing (BMS) and dose to organs at risk (OARs) for intensity modulated proton therapy (IMPT) for women with locally advanced cervical cancer (LACC).

MATERIALS AND METHODS

Twenty LACC patients were retrospectively included. IMPT plans were created for each patient using automated treatment planning. These plans progressively reduced bone marrow mean doses by steps of 1 GyRBE, while constraining target coverage and conformality. The relation between bone marrow dose and bladder, small bowel, rectum, and sigmoid doses was evaluated.

RESULTS

A total of 140 IMPT plans were created. Plans without BMS had an average [range] bone marrow mean dose of 17.3 [14.7-21.6] GyRBE , which reduced to 12.0 [10.0-14.0] GyRBE with maximum BMS. The mean OAR dose [range] increased modestly for 1 GyRBE BMS: 0.2 [0.0 - 0.6] GyRBE for bladder, 0.3 [-0.2 - 0.7] GyRBE for rectum, 0.4 [0.1 - 0.8] GyRBE for small bowel, and 0.2 [-0.2 - 0.4] GyRBE for sigmoid. Moreover, for maximum BMS, mean OAR doses [range] escalated by 3.3 [0.1 - 6.7] GyRBE for bladder, 5.8 [1.8 - 12.4] GyRBE for rectum, 3.9 [1.6 - 5.9] GyRBE for small bowel, and 2.7 [0.6 - 5.9] GyRBE for sigmoid.

CONCLUSION

Achieving 1 GyRBE BMS for IMPT is feasible for LACC patients with limited dosimetric impact on other OARs. While further bone marrow dose reduction is possible for some patients, it may increase OAR doses substantially for others. Hence, we recommend a personalized approach when introducing BMS into clinical IMPT treatment planning to carefully assess individual patient benefits and risks.

Microcystic elongated and fragmented (MELF) pattern of invasion: Molecular features and prognostic significance in the PORTEC-1 and -2 trials

OBJECTIVE

Microcystic, elongated fragmented (MELF) pattern of myometrial invasion is a distinct histologic feature occasionally seen in low-grade endometrial carcinomas (EC). The prognostic relevance of MELF invasion was uncertain due to conflicting data, and it had not yet appropriately been studied in the context of the molecular EC classification. We aimed to determine the relation of MELF invasion with clinicopathological and molecular characteristics, and define its prognostic relevance in early-stage low/intermediate risk EC.

METHODS

Single whole tumor slides of 979 (85.8%) out of 1141 (high)intermediate-risk EC of women who participated in the PORTEC-1/-2 trials were available for review. Clinicopathological and molecular features were compared between MELF invasion positive and negative cases. Time-to-event analyses were done by Kaplan-Meier method, log-rank tests and Cox' proportional hazards models.

RESULTS

MELF invasion was found in 128 (13.1%) cases, and associated with grade 1-2 histology, deep myometrial invasion and substantial lymph-vascular space invasion (LVSI). 85.6% of MELF invasion positive tumors were no-specific-molecular-profile (NSMP) EC. NSMP EC with MELF invasion were CTNNB1 wild type in 92.2% and KRAS mutated in 24.4% of cases. Risk of recurrence was lower for MELF invasion positive as compared to MELF invasion negative cases (4.9% vs. 12.7%, p = 0.026). However, MELF invasion had no independent impact on risk of recurrence (HR 0.65, p = 0.30) after correction for clinicopathological and molecular factors.

CONCLUSIONS

MELF invasion has no independent impact on risk of recurrence in early-stage EC, and is frequently observed in low-grade NSMP tumors. Routine assessment of MELF invasion has no clinical implications and is not recommended.

Brachytherapy quality assurance in the PORTEC-4a trial for molecular-integrated risk profile guided adjuvant treatment of endometrial cancer

OBJECTIVE

The PORTEC-4a trial investigates molecular-integrated risk profile guided adjuvant treatment for endometrial cancer. The quality assurance programme included a dummy run for vaginal brachytherapy prior to site activation, and annual quality assurance to verify protocol adherence. Aims of this study were to evaluate vaginal brachytherapy quality and protocol adherence.

METHODS

For the dummy run, institutes were invited to create a brachytherapy plan on a provided CT-scan with the applicator in situ. For annual quality assurance, institutes provided data of one randomly selected brachytherapy case. A brachytherapy panel reviewed and scored the brachytherapy plans according to a checklist.

RESULTS

At the dummy run, 15 out of 21 (71.4%) institutes needed adjustments of delineation or planning. After adjustments, the mean dose at the vaginal apex (protocol: 100%; 7 Gy) decreased from 100.7% to 99.9% and range and standard deviation (SD) narrowed from 83.6-135.1 to 96.4-101.4 and 8.8 to 1.1, respectively. At annual quality assurance, 22 out of 27 (81.5%) cases had no or minor and 5 out of 27 (18.5%) major deviations. Most deviations were related to delineation, mean dose at the vaginal apex (98.0%, 74.7-114.2, SD 7.6) or reference volume length.

CONCLUSIONS

Most feedback during the brachytherapy quality assurance procedure of the PORTEC-4a trial was related to delineation, dose at the vaginal apex and the reference volume length. Annual quality assurance is essential to promote protocol compliance, ensuring high quality vaginal brachytherapy in all participating institutes.

The Effect of the Time Interval Between Radiation and Hyperthermia on Clinical Outcome in 400 Locally Advanced Cervical Carcinoma Patients

Background: Addition of deep hyperthermia to radiotherapy results in improved local control (LC) and overall survival compared to radiotherapy alone in cervical carcinoma patients. Based on preclinical data, the time interval between radiotherapy, and hyperthermia is expected to influence treatment outcome. Clinical studies addressing the effect of time interval are sparse. The repercussions for clinical applications are substantial, as the time between radiotherapy and hyperthermia should be kept as short as possible. In this study, we therefore investigated the effect of the time interval between radiotherapy and hyperthermia on treatment outcome. Methods: We analyzed all primary cervical carcinoma patients treated between 1996 and 2016 with thermoradiotherapy at our institute. Data on patients, tumors and treatments were collected, including the thermal dose parameters TRISE and CEM43T90. Follow-up data on tumor status and survival as well as late toxicity were collected. Data was analyzed using Cox proportional hazards analysis and Kaplan Meier analysis. Results: 400 patients were included. Kaplan Meier and univariate Cox analysis showed no effect of the time interval (range 30-230 min) on any clinical outcome measure. Besides known prognostic factors, thermal dose parameters TRISE and CEM43T90 had a significant effect on LC. In multivariate analysis, the thermal dose parameter TRISE (HR 0.649; 95% CI 0.501-0.840) and the use of image guided brachytherapy (HR 0.432; 95% CI 0.214-0.972), but not the time interval, were significant predictors of LC and disease specific survival. Conclusions: The time interval between radiotherapy and hyperthermia, up to 4 h, has no effect on clinical outcome. These results are re-ensuring for our current practice of delivering hyperthermia within maximal 4 h after radiotherapy.

Ten-year results of the PORTEC-2 trial for high-intermediate risk endometrial carcinoma: improving patient selection for adjuvant therapy

Background

PORTEC-2 was a randomised trial for women with high-intermediate risk (HIR) endometrial cancer, comparing pelvic external beam radiotherapy (EBRT) with vaginal brachytherapy (VBT). We evaluated long-term outcomes combined with the results of pathology review and molecular analysis.

Methods

427 women with HIR endometrial cancer were randomised between 2002–2006 to VBT or EBRT. Primary endpoint was vaginal recurrence (VR). Pathology review was done in 97.4%, combined with molecular analysis.

Results

Median follow-up was 116 months; 10-year VR was 3.4% versus 2.4% for VBT vs. EBRT (p = 0.55). Ten-year pelvic recurrence (PR) was more frequent in the VBT group (6.3% vs. 0.9%, p = 0.004), mostly combined with distant metastases (DM). Ten-year isolated PR was 2.5% vs. 0.5%, p = 0.10, and DM 10.4 vs. 8.9% (p = 0.45). Overall survival for VBT vs. EBRT was 69.5% vs. 67.6% at 10 years (p = 0.72). L1CAM and p53-mutant expression and substantial lymph-vascular space invasion were risk factors for PR and DM. EBRT reduced PR in cases with these risk factors.

Conclusion

Long-term results of the PORTEC-2 trial confirm VBT as standard adjuvant treatment for HIR endometrial cancer. Molecular risk assessment has the potential to guide adjuvant therapy. EBRT provided better pelvic control in patients with unfavourable risk factors.

Vaginal brachytherapy versus pelvic external beam radiotherapy for patients with endometrial cancer of high-intermediate risk (PORTEC-2): an open-label, non-inferiority, randomised trial

BACKGROUND

After surgery for intermediate-risk endometrial carcinoma, the vagina is the most frequent site of recurrence. This study established whether vaginal brachytherapy (VBT) is as effective as pelvic external beam radiotherapy (EBRT) in prevention of vaginal recurrence, with fewer adverse effects and improved quality of life.

METHODS

In this open-label, non-inferiority, randomised trial undertaken in 19 Dutch radiation oncology centres, 427 patients with stage I or IIA endometrial carcinoma with features of high-intermediate risk were randomly assigned by a computer-generated, biased coin minimisation procedure to pelvic EBRT (46 Gy in 23 fractions; n=214) or VBT (21 Gy high-dose rate in three fractions, or 30 Gy low-dose rate; n=213). All investigators were masked to the assignment of treatment group. The primary endpoint was vaginal recurrence. The predefined non-inferiority margin was an absolute difference of 6% in vaginal recurrence. Analysis was by intention to treat, with competing risk methods. The study is registered, number ISRCTN16228756.

FINDINGS

At median follow-up of 45 months (range 18-78), three vaginal recurrences had been diagnosed after VBT and four after EBRT. Estimated 5-year rates of vaginal recurrence were 1.8% (95% CI 0.6-5.9) for VBT and 1.6% (0.5-4.9) for EBRT (hazard ratio [HR] 0.78, 95% CI 0.17-3.49; p=0.74). 5-year rates of locoregional relapse (vaginal or pelvic recurrence, or both) were 5.1% (2.8-9.6) for VBT and 2.1% (0.8-5.8) for EBRT (HR 2.08, 0.71-6.09; p=0.17). 1.5% (0.5-4.5) versus 0.5% (0.1-3.4) of patients presented with isolated pelvic recurrence (HR 3.10, 0.32-29.9; p=0.30), and rates of distant metastases were similar (8.3% [5.1-13.4] vs 5.7% [3.3-9.9]; HR 1.32, 0.63-2.74; p=0.46). We recorded no differences in overall (84.8% [95% CI 79.3-90.3] vs 79.6% [71.2-88.0]; HR 1.17, 0.69-1.98; p=0.57) or disease-free survival (82.7% [76.9-88.6] vs 78.1% [69.7-86.5]; HR 1.09, 0.66-1.78; p=0.74). Rates of acute grade 1-2 gastrointestinal toxicity were significantly lower in the VBT group than in the EBRT group at completion of radiotherapy (12.6% [27/215] vs 53.8% [112/208]).

INTERPRETATION

VBT is effective in ensuring vaginal control, with fewer gastrointestinal toxic effects than with EBRT. VBT should be the adjuvant treatment of choice for patients with endometrial carcinoma of high-intermediate risk.

FUNDING

Dutch Cancer Society.