[Hypofractionated radiotherapy, a standard in breast cancer?]

[Radiotherapy in elderly patients, recommendations for the main localizations: Breast, prostate and gynaecological cancers]

Modifications of radiotherapy indications or schedules because of age could be discussed in view of a different evolution of the disease or because of specific toxicities. One important aim is to decrease the number of hospital transports. For breast cancer, the rate of local relapse after lumpectomy is lower in old patients; moreover, characteristics of the disease are often more favourable (hormonosensitivity, low grade). However, adjuvant irradiation decreases significantly the incidence of breast relapse and must be systematically proposed. Hypofractionnated schedules must be recommended; limited data are available for accelerated partial breast irradiation in old women and these techniques must not be used in routine. For low or intermediate risk prostate cancer, assessment of comorbidities is crucial before considering any invasive treatment. A life expectancy of at least 10 years is required if a curative approach, potentially toxic is proposed. In this case, radiotherapy is often the good choice, giving less sequelae than surgery. The indication of androgen deprivation must take into account cardiovascular and bone history. Management of gynaecological cancers must follow the same recommendations as in young women. Exclusive postoperative brachytherapy must be recommended in early stage endometrial carcinomas. Brachytherapy must be also systematically integrated in the radiotherapy program for cervix cancers, even in old women.

[Radiosensitivity settings in breast cancer]

Breast cancers are highly radiosensitive since the risk of recurrences and of mortality after adjuvant radiotherapy following breast-conserving surgery is decreased by 15.7% and 3.8%, respectively at 10 years. The total dose if irradiation also significantly increases local control: a boost of 16 Gy to the tumour bed after breast-conserving surgery reduces the absolute risk of recurrence by 4% at 10 years. Breast cancers are sensitive to the dose per fraction, as shown by the results from four randomized trials which compared standard irradiation (50 Gy/25 fractions) with a hypofractionated scheme: no statistical difference was observed in locoregional recurrence and overall survival at 10 years. The α/β ratio, which reflects the dose per fraction and is theoretically over 10 Gy for tumour tissues, has been estimated between 2.2 and 4.4 Gy for breast cancers. Molecular abnormalities, such as overexpression of HER1 (especially in triple negative breast cancer) and HER2, induce a higher radioresistance. In vitro studies showed that targeted therapies, which block these receptors, increase breast cancer radiosensitivity. Tumour stem cells have been identified in breast cancers and are characterized by a higher radioresistance. This radioresistance could be related to a better repair of radiation-induced DNA damages and a decrease of reactive oxygen species (ROS), which are involved in their occurrence. In the future, a better understanding of genetics tumour abnormalities will allow to identify new radiosensitivity settings in breast cancers.

Hypofractionated radiotherapy induces miR-34a expression and enhances apoptosis in human nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a relatively radiosensitive disease. However, the therapeutic effects of radiotherapy are not always satisfactory due to radioresistance. The hypofractionated schema is currently widely used in clinical practice. In the present study, we investigated the effects of hypofractionated radiotherapy on NPC cells and explored the mechanisms involved. In addition, we aimed to determine the role of miR-34a in the effects of hypofractionated radiotherapy and whether these effects occur in a p53-dependent manner. For this purpose, we used CNE1 and CNE2 NPC cells which were subjected to hyperfractionated and hypofractionated radiotherapy. The viability of the cells was measured by MTT assay and acridine orange (AO) and ethidium bromide (EB) staining was used to observe morphological changes. In addition, Annexin V-propidium iodide (PI) staining and flow cytometry were used to determine the number of apoptotic cells and mRNA and protein expression was measured by qPCR and western blot analysis, respectively. The results revealed that hypofractionated radiotherapy enhanced apoptosis and increased the expression of miR-34a and p53 in the NPC cells. In addition, it stimulated p53 promoter activity and downregulated the protein expression of c-Myc in the human NPC cells. Furthermore, the knockdown of miR-34a suppressed the growth inhibitory effects induced by hypofractionated radiotherapy. Thus, our results suggest that the enhanced apoptosis of NPC cells may be associated with the miR-34a-mediated suppression of c-Myc in a p53-dependent manner.

[State of the art and perspectives of accelerated partial breast irradiation in 2014]

In the frame of treatment de-escalation and personalization, accelerated partial breast irradiation is taking its place in the breast cancer therapeutic options. This study analyzed the results of phase III randomized trials having compared accelerated partial breast irradiation versus whole breast irradiation. Currently, among those trails, six proposed some results regarding efficacy and/or toxicity. Globally, the non-randomized studies confirmed the expected results showing a low rate of local recurrence and toxicity. The first results of the phase III randomized trials showed encouraging data in terms of local control while the toxicity varied mainly according to the accelerated partial breast irradiation technique used. However, the follow-up of the majority of these studies remains insufficient. The strict respect of accelerated partial breast irradiation indications likely represents one of the key factors of the therapeutic success. The next results could allow proposing a better definition of the accelerated partial breast irradiation selection criteria.