Bénéfices de la radiothérapie avec asservissement respiratoire dans le traitement du cancer du sein

[Concomitant radiotherapy and trastuzumab: Rational and clinical implications]

The HER2 receptor (Human Epidermal Growth Receptor 2) is a transmembrane receptor with tyrosine kinase activity that is over-expressed in 25-30 % of breast carcinomas. Its activation is associated with an exaggeration of cell proliferation with an increase in repair capacity resulting in increased radioresistance. On cardiac tissues, HER2 receptor activation plays a cardio-protective role. Trastuzumab, the first anti-HER2 drug used to treat patients with breast cancer overexpressing HER2 receptor , inhibits the cascade of reactions resulting in the proliferation of tumor cells, thus restoring cellular radiosensitivity. However, the combination of Trastuzumab with radiation therapy also removes HER2 receptor cardio-protective role on myocardial cells which increases the risk of cardiotoxicity. Thus, the concomitant association of these two modalities has long been a subject of controversy. Recent advances in radiation therapy technology and early detection of cardiac injury may limit the cardiotoxicity of this combination. Through this review, we developed the biological basis and the benefit-risk of concomitant combination of radiotherapy and Trastuzumab in adjuvant treatment of breast cancers overexpressing HER2 and we discuss the modalities of its optimization.

[Left-sided breast cancer locoregional radiation therapy with rotational intensity-modulated irradiation and deep inspiration breath hold: Dosimetric comparison]

PURPOSE

Adjuvant left-sided breast cancer locoregional radiotherapy can be accounted for long-term cardiac toxicity. The deep inspiration breath hold techniques can reduce cardiac doses. Only a few studies have investigated rotational intensity-modulated radiotherapy with deep inspiration breath hold.

MATERIAL AND METHODS

We conducted a dosimetric study comparing rotational intensity-modulated radiotherapy in free breathing with deep inspiration breath hold for irradiation of left breast cancer and locoregional lymph nodes. Doses to organs at risk were compared, as well as doses to coronary arteries, left anterior descending coronary artery region, and aortic valve.

RESULTS

The data from nine patients were included in the study. Treatment plans were comparable for target volumes. The deep inspiration breath hold delivery technique, compared with free breathing, reduced radiation dose to the heart (mean dose 4.8Gy vs. 6.6Gy, p=0.008; dose in 2% of the volume 16.8Gy vs. 23.3Gy, p=0.008; volume receiving 25Gy 0.8% vs. 2,2%, p=0.008; volume receiving 30Gy 0.4% vs. 1.2%, p=0.009), as well as to the right coronary artery (mean dose 6Gy vs. 8.9Gy, p=0.028), to the left anterior descending artery (mean dose 9.6Gy vs. 14.6Gy, p=0.021), to the left anterior descending coronary artery region (dose in 2% of the volume 17.4Gy vs. 24.6Gy, p=0.021), and to the aortic valve (mean dose 4.8Gy vs. 7Gy, p=0.028). Other doses to organs at risk were similar.

CONCLUSION

Rotational intensity-modulated radiotherapy with deep inspiration breath hold is associated with better sparing of the heart, on the right and left anterior descending coronary arteries, and on the aortic valve, compared with free breathing techniques, for adjuvant left breast cancer locoregional irradiation.

[Radiation-related heart toxicity: Update in women]

Breast cancer is a common diagnosis in women and thus women are at risk of radiation-induced heart disease, in particular during radiotherapy for left breast cancer and when the internal mammary chain is included. Rates of major cardiac events increase with younger age at the time of irradiation, diagnosis before 1990s, higher radiation doses, coexisting cardiovascular risk factors and adjuvant cardiotoxic chemotherapy. Radiation-induced heart disease comprises a spectrum of cardiac pathologies, including pericardial disease, cardiomyopathy, coronary artery disease and valvular disease. The cardiac injury can appear a long time after radiotherapy and can consist of complex lesions with poor prognosis. The disciplines of cardiology and oncology have increasingly recognized the benefits of collaborating in the care of cancer patients with cardiac disease, developing guidelines for the assessment and management of radiation-related cardiovascular disease. We could consider screening patients with previous chest radiation every 5 years with transthoracic echocardiography and functional imaging. However, prevention remains the primary goal, using cardiac sparing doses and avoidance techniques in radiotherapy to improve patient survival.

[Establishing margins from CTV to PTV in breast cancer treatment]

The benefit of postoperative radiotherapy for breast cancer both in terms of local control and overall survival is widely acknowledged. Today, technological advances in simulation imaging and positioning control enable the definition of new margins from CTV to PTV. Improvements in mathematical modeling of random and systematic errors impact the treatment plans. However, there is no universal absolute value to consistently determine the margins from CTV to PTV. It is down to each centre to assess and correct as much as possible uncertainties due to positioning and internal movements depending on techniques and methods used for the implementation of treatment and monitoring. IMRT and respiratory gating techniques for breast radiotherapy will be considered more systematically in the years to come.