[Prevention of radio-induced cancers]

[Does radiation therapy for prostate cancer increase the risk of second cancers?]

PURPOSE

The increased risk of second cancer after prostate radiotherapy is a debated clinical concern. The objective of the study was to assess the risk of occurrence of second cancers after prostate radiation therapy based on the analysis the literature, and to identify potential factors explaining the discrepancies in results between studies.

MATERIALS AND METHODS

A review of the literature was carried out, comparing the occurrence of second cancers in patients all presenting with prostate cancer, treated or not by radiation.

RESULTS

This review included 30 studies reporting the occurrence of second cancers in 2,112,000 patients treated or monitored for localized prostate cancer, including 1,111,000 by external radiation therapy and 103,000 by brachytherapy. Regarding external radiation therapy, the average follow-up was 7.3years. The majority of studies (80%) involving external radiation therapy, compared to no external radiation therapy, showed an increased risk of second cancers with a hazard ratio ranging from 1.13 to 4.9, depending on the duration of the follow-up. The median time to the occurrence of these second cancers after external radiotherapy ranged from 4 to 6years. An increased risk of second rectal and bladder cancer was observed in 52% and 85% of the studies, respectively. Considering a censoring period of more than 10 years after irradiation, 57% and 100% of the studies found an increased risk of rectal and bladder cancer, without any impact in overall survival. Studies of brachytherapy did not show an increased risk of second cancer. However, these comparative studies, most often old and retrospective, had many methodological biases.

CONCLUSION

Despite numerous methodological biases, prostate external radiation therapy appears associated with a moderate increase in the risk of second pelvic cancer, in particular bladder cancer, without impacting survival. Brachytherapy does not increase the risk of a second cancer.

COVID-19-Associated Pneumonia: Radiobiological Insights

The evolution of SARS-CoV-2 pneumonia to acute respiratory distress syndrome is linked to a virus-induced “cytokine storm”, associated with systemic inflammation, coagulopathies, endothelial damage, thrombo-inflammation, immune system deregulation and disruption of angiotensin converting enzyme signaling pathways. To date, the most promising therapeutic approaches in COVID-19 pandemic are linked to the development of vaccines. However, the fight against COVID-19 pandemic in the short and mid-term cannot only rely on vaccines strategies, in particular given the growing proportion of more contagious and more lethal variants among exposed population (the English, South African and Brazilian variants). As long as collective immunity is still not acquired, some patients will have severe forms of the disease. Therapeutic perspectives also rely on the implementation of strategies for the prevention of secondary complications resulting from vascular endothelial damage and from immune system deregulation, which contributes to acute respiratory distress and potentially to long term irreversible tissue damage. While the anti-inflammatory effects of low dose irradiation have been exploited for a long time in the clinics, few recent physiopathological and experimental data suggested the possibility to modulate the inflammatory storm related to COVID-19 pulmonary infection by exposing patients to ionizing radiation at very low doses. Despite level of evidence is only preliminary, these preclinical findings open therapeutic perspectives and are discussed in this article.

[Low-dose irradiation of non-malignant diseases: Did we throw the baby out with the bathwater?]

The irradiation of non-malignant diseases, essentially for anti-inflammatory purpose, have been largely proposed and performed worldwide until the 1970-80s. At that time, the better assessment of the radio-induced malignancies, essentially in children and young patients, as well as the efficacy of the new anti-inflammatory drugs (steroids and non-steroids), led to the almost disappearance of those techniques, at least in France. In contrast, our German colleagues are still going on treating about 50,000 patients per year for non-malignant (more or less severe) diseases. After a short historical overview, the present article suggests that we were possibly going too far in the rejection of those low-dose irradiations for benign lesions. The recent emergence of new preclinical data, the better understanding of the risk of radio-induced secondary tumours (almost nil in the elderly), and the severity of some situations, such as the cytokine storm of the COVID-19, should probably lead us to reconsider those low - and sometimes very low (less than 1Gy) - irradiations for well-selected indications in the elderly.

[Overall survival and survival without local recurrence in case of radiotherapy of the tumor bed of ductal carcinomas in situ of the breast: Review of the literature]

INTRODUCTION

Carcinomas in situ represent more than 15 to 20% of breast cancers. Radiotherapy of whole breast is part of the therapeutic standard and follows surgery. However, the indication of tumor bed irradiation is still controversial and heterogeneous according to international practice even though it is a very frequent clinical situation. The aim of this study is to define the indications of tumor bed irradiation in the context of ductal carcinomas in situ and to discuss accelerated partial irradiation of the breast.

METHOD

The selected papers were published between 2015 and 2020 and included as MeSH terms "ductal carcinoma in situ" and "boost" for the analysis of tumor bed irradiation, and "ductal carcinoma in situ" and "accelerated partial breast irradiation" for the analysis of accelerated partial irradiation.

RESULTS

Boost was more often performed when risk factors for local recurrence were present, such as age less than 40 or 50 years old, clinical mode of detection, tumor size greater than 15 to 20mm, high nuclear grade, presence of necrosis, positive or insufficient surgical margins, associated atypical hyperplastic lesions, and lobular carcinoma in situ. Accelerated partial irradiation is an option for favorable or intermediate prognosis CCIS, further studies involving more patients are required.

CONCLUSION

Radiotherapy of the mammary gland in the context of DCIS has shown its effectiveness in terms of local and locoregional control of the disease, thus reducing in situ and infiltrating recurrences. However, the indication of operating bed irradiation is still debated, and the practice is very heterogeneous depending on the country. Another possible alternative for patients with a favorable prognosis and a small tumor bed volume would be IPA.

[Influence of age on indications and modalities of radiation therapy: What to keep in mind for adolescents and young adults?]

When using radiation therapy for adolescents and young adults (AYA), paediatricians, adults' oncologists and radiation oncologists need to keep in mind several particularities through the whole therapeutic process. They embrace the indication, target volumes, prescribed dose, treatment techniques and follow-up. Indeed, the young age and the cancer features that characterised this population influence the modalities of irradiation. This article highlights the key points of AYA care with radiation therapy.

Mucocèles nasosinusiennes post-radiques à propos de trois cas

Nasosinusal mucoceles, although benign, are aggressive and sometimes destructive lesions. They may occur as a result of trauma, infection, sinus surgery and head and neck radiation. We describe three patients presenting mucocele, with the history of nasopharyngeal and temporal fossa cancers treated by radiotherapy.

[Radiation therapy planning for Hodgkin lymphoma: Focus on intensity-modulated radiotherapy, gating, protons. Which techniques to best deliver radiation?]

The optimization of radiotherapy in these young and long-lived survivors raises the question about the interest of using modern techniques to allow a better distribution of the dose. The choice of the irradiation technique must take into account the incidence of side effects related to radiation. In this context, the definition of the target volumes as well as the verification and monitoring of the delivered processing are essential. International recommendations for treatment fields are based on the "involved node radiotherapy" concept. The best irradiation technique to use remains to be defined. The use of intensity-modulated radiotherapy improves the coverage and reduces the dose to the organs at risk with a variable gain depending on the topography of the lymph nodes: upper or lower mediastinum, right or left lateralization, the techniques used. The deep inspiration breath-hold technique allows an increase of the pulmonary volume, extension of the mediastinum with an up down of the heart which make possible to move the planning target volume away from the cardiac structures. The volumetric-modulated arctherapy technique with several arches can be particularly interesting to reduce the dose to the breasts, as well as tomotherapy when bulky disease. Proton therapy with the Bragg peak specificity can play a key role in limiting doses to organs at risk, when robust planning that will take into account geometric and physical uncertainties is available. The heterogeneity of Hodgkin lymphomas in terms of volume, shape and initial location are the key elements to take into account when choosing the preferred radiotherapy technique.

Second malignancies after permanent implant prostate cancer brachytherapy: A single-institution study of 675 patients treated between 1999 and 2003

PURPOSE

To analyse the rate of secondary malignancies observed in a series of 675 prostate cancer patients who underwent a permanent implant brachytherapy between 1999 and 2003, and to compare the incidence with the expected rate in a matched general French population.

MATERIAL AND METHODS

The cohort included low-risk patients and a selection of "favourable-intermediate" risk patients. All patients were homogeneously treated using an intraoperative dynamic planning prostate brachytherapy technique, with loose 125-iodine seeds and a prescription dose of 145Gy. The mean follow-up was 132 months.

RESULTS

The 10-year overall survival for the entire cohort was 92% (95% confidence interval [CI]: 90-94). The 10-year relapse-free survival rate was 82% (95% CI: 79-85). Overall, 61 second cancers were registered. When comparing with a matched general French population, the standard incidence ratio (SIR) for bladder cancer was 1.02 (95% CI: 0.46-1.93). For colorectal cancer, the SIR was 0.45 (95% CI: 0.19-0.89). For lung cancer, the SIR was 0.38 (95% CI: 0.17-0.76). The SIR for all cancers was 0.61 (95% CI: 0.47-0.79). When excluding secondary colorectal and lung cancers (both with low SIRs in this series), the SIR for all cancers was 1.06 (95% CI: 0.77-1.29).

CONCLUSION

With a mean follow-up of more than 11 years, this series does not detect any excess risk of second cancers associated with permanent implant prostate brachytherapy. However, due to power limitation, a small increase in the risk of secondary malignancies cannot be totally ruled out.