A priori quality assurance using a benchmark case of the randomized phase 2 GORTEC 2014-14 in oligometastatic head and neck cancer patients

PURPOSE

A Benchmark Case (BC) was performed as part of the quality assurance process of the randomized phase 2 GORTEC 2014-14 OMET study, testing the possibility of multisite stereotactic radiation therapy (SBRT) alone in oligometastatic head and neck squamous cell carcinoma (HNSCC) as an alternative to systemic treatment and SBRT.

MATERIAL AND METHODS

Compliance of the investigating centers with the prescription, delineation, planning and evaluation recommendations available in the research protocol was assessed. In addition, classical dosimetric analysis was supplemented by quantitative geometric analysis using conformation indices.

RESULTS

Twenty centers participated in the BC analysis. Among them, four major deviations (MaD) were reported in two centers. Two (10%) centers in MaD had omitted the satellite tumor nodule and secondarily validated after revision. Their respective DICE indexes were 0.37 and 0 and use of extracranial SBRT devices suboptimal There were significant residual heterogeneities between participating centers, including those with a similar SBRT equipment, with impact of plan quality using standard indicators and geometric indices.

CONCLUSION

A priori QA using a BC conditioning the participation of the clinical investigation centers showed deviations from good SBRT practice and led to the exclusion of one out of the twenty participating centers. The majority of centers have demonstrated rigorous compliance with the research protocol. The use of quality indexes adds a complementary approach to improve assessment of plan quality.

[Low dose radiotherapy for COVID-19 pneumopathy: Biological rationale and literature review]

La pandémie de coronavirus disease 2019 (covid-19) due au severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) évolue depuis un peu plus d’un an. Si la majorité des formes est bénigne, des pneumopathies graves, voire mortelles, se développent chez certains patients plus à risque. De nombreuses pistes thérapeutiques ont été explorées avec cependant trop peu d’impact sur la mortalité. C’est dans ce contexte que Kirkby et Mackenzie ont rappelé en avril 2020 les propriétés anti-inflammatoires de la radiothérapie de faible dose (délivrant moins de 1 Gy) et son utilisation dans le traitement des pneumopathies bactériennes et virales avant l’ère des antibiotiques. En effet, de larges données in vitro et in vivo ont démontré le rationnel biologique à l’origine de la diminution de l’inflammation après une radiothérapie de faible dose dans de nombreuses pathologies. Depuis un an, trois essais cliniques de phase I/II ont été publiés ainsi qu’un essai randomisé, rapportant la faisabilité et l’amélioration clinique et biologique d’un traitement bipulmonaire par une dose 0,5 à 1 Gy. Treize autres études, dont une phase III randomisée, sont en cours dans le monde. Celles-ci pourront permettre de mieux apprécier les effets de la radiothérapie de faible dose pour la pneumonie à SARS-CoV-2. Cette revue s’attache à rappeler le rationnel biologique de l’utilisation de la radiothérapie de faible dose dans les pneumopathies, et de rapporter les résultats des essais publiés ou en cours sur son utilisation spécifique pour la pneumopathie à SARS-CoV-2.

[Interobserver variability study for daily cone beam computed tomography registration of prostate volumetric modulated arc therapy]

PURPOSE

This work evaluated the interobserver variability in cone beam computed tomography (CBCT) registration for prostate cancers treated with intensity-modulated radiotherapy.

MATERIAL AND METHODS

Twelve technologists realized 286 CBCT/CT registrations (bone registration followed by prostate to prostate registration). The registration results were compared to those obtained by two radiation oncologists (reference). Each technologist reported the shifts calculated by the software in all three axes. A statistical analysis allowed us to calculate the minimum threshold under which 95% of the observers found similar values. A variance analysis followed by the post hoc test were used to find differences in interobserver registration variability and determine whether any individual users performed registrations which differed significantly from those of the other users.

RESULTS

The registration differences compared to the reference in the three directions in terms of 95th percentile are: 2.1mm left-right, 3.5mm target-gun, 7.3mm anterior-posterior. In the posterior direction, 4% of the observers have found differences superior to 8mm, margin used in routine without the use of a daily CBCT. The variance test revealed a P-value <0.05 only for target-gun and for all observers there was no significant difference compared to the reference.

CONCLUSION

This study confirmed the interest of a 3D tissue registration for prostate treatments. The registration study showed a good interobserver reproducibility. This showed the importance of a daily CBCT/CT registration in prostate treatment with the possibility of a planning target volume margin reduction in the three directions. An evaluation of a partial delegation of registration to technologists should be done by the radiation oncologists.

Traitements préopératoires des cancers rectaux

Surgery alone is no longer appropriate to the treatment of T3-T4 resecable rectal cancer. Preoperative chemoradiotherapy has recently been approved as the new standard treatment. This approach improves local control with local failure rate raranging now around 6-8%. However, it does not impact on overall survival. It becomes urgent to develop new concepts and a basic research in the understanding of the biological mechanisms that may explain the resistance of the micrometastatic process.

Conduite à tenir devant une ascension du PSA après rémission complète postprostatectomie ?

Between twenty and to forty percent of patients will develop an isolated PSA failure after a radical prostatectomy. Pelvic irradiation is a therapeutic option with curative intention. It is the best therapeutic option for young people with good prognostic factors. Combined radiation with hormonal or chemotherapy should be evaluated in patients with poor prognostic factors. For patients with a short life expectancy, hormonotherapy or a watch and see policy are acceptable options.

Radiothérapie pelvienne pour récidive biochimique isolée après prostatectomie pour cancer de prostate : quels volumes ?

After prostatectomy, radiotherapy is a potential curable treatment. From the surgery series, it is possible to identify all the localization at risk in case of biochemical relapse after prostatectomy. The target volume of irradiation has to be defined according to the pathological findings. The CTV is limited to the pelvic fascia laterally, to the anterior wall of the rectum behind. The inferior limit includes the anastomosis, and the superior is easier to define with the length of the prostatic gland. The inclusion of area of seminal vesicles and pelvic node areas should be discussed. The use of surgical clips on the anastomosis and image fusionning techniques including the preoperative imaging would help physicians to define the CTV's limits.

Radiation and chemoradiation therapy for esophageal adenocarcinoma

The aims of preoperative chemoradiation therapy (preop-CRT) for esophageal adenocarcinoma are to reduce incomplete local resection (R1,R2), local and systemic recurrences that are reported in up to 30% of patients who undergo surgery alone. Phase II studies of preop-CRT, with radiation doses in the 40-50 Gy range, and concurrent chemotherapy with 5-fluorouracil (5-FU)-cisplatin +/- paclitaxel, or cisplatin-paclitaxel, have reported subsequent RO resection rates of 80%-100%, with tumor sterilization achieved in 8%-49% of cases, and consequently improved local control. New chemotherapy regimens omitting 5-FU have reduced the incidence of severe esophagitis, unplanned hospitalization, with comparable efficacy. Among three randomised trials that compared preop-CRT to surgery alone, one shown a debatable survival advantage. Reducing local recurrence rates lead to a switch to more distant failures, and increasing the radiation dose beyond 45 Gy appears to be of little value. However, it should be remembered that preop-CRT has associated toxicity, and may increase postoperative mortality. Novel strategies, which include induction with chemotherapy followed by preop-CRT, and for radiation therapy, three dimensional conformation techniques, image fusioning, and improved definition of treatment volumes, are still considered experimental and should be tested in specialized centers.

La radiothérapie de conformation avec et sans modulation d'intensité dans le traitement du cancer localisé de la prostate

Conformal radiation therapy has now to be considered as a standard treatment of localized prostatic adenocarcinomas. Using conformational methods and intensity modulated radiation therapy requires a rigorous approach for their implementation in routine, focused on the reproducibility of the treatment, target volume definitions, dosimetry, quality control, setup positioning. In order to offer to the largest number of patients high-dose treatment, the clinicians must integrate as prognostic factors accurate definition of microscopic extension as well as the tolerance threshold of critical organs. High-dose delivery is expected to be most efficient in intermediary risks and locally advanced diseases. Intensity modulated radiation therapy is specifically dedicated to dose escalation. Perfect knowledge of classical constraints of conformal radiation therapy is required. Using such an approach in routine needs a learning curve including the physicists and a specific quality assurance program.

[Cancer of the rectum: target volumes for preoperative radiotherapy]

Preoperative radiotherapy is the standard treatment for locally advanced resectable rectal adenocarcinoma. The total mesorectal excision leads to a dramatic increase of local control rate. Thus, the mesorectal space is the usual field for the spread of rectal cancers cells. It could therefore be considered as the clinical target volume (CTV) in the preoperative conformational radiotherapy. From the anatomical basis and radiological contributions, we propose several CTVs for different locations of rectal carcinoma.