Evaluation of acute skin toxicity of breast radiotherapy using thermography: Results of a prospective single-centre trial.

PURPOSE: Radiotherapy is a common adjuvant treatment of breast cancer. Acute radiation-induced dermatitis is a frequent side effect. We hypothesized whether it is possible to capture the increase of local temperature as a surrogate of the inflammatory state induced by radiotherapy. We designed a prospective, observational, single-centre study to acquire data on temperature rise in the treated breast during the course of radiotherapy, establish a possible association with the occurrence of dermatitis and investigate the predictive value of temperature increase in future occurrences of radiation-induced dermatitis. PATIENTS AND METHODS: All patients presenting for neoadjuvant or adjuvant radiotherapy during the course of breast cancer treatment at the university hospital of Martinique were considered for inclusion. Every week, patients were examined by two trained investigators for the occurrence of radiation-induced dermatitis, graded based on Radiotherapy Oncology Group, Common Terminology Criteria for Adverse Events v.4.0 and Wright scales. A frontal thermal image of torso was taken in strictly controlled conditions, with a calibrated TE-Q1 camera (Thermal Expert, i3systems, Daejeon, Korea). We studied temperature differences between the irradiated breast or thoracic wall and the contralateral area. For each thermal picture, we measured the difference in maximum temperature as well as the difference in minimum temperature and the difference in the average temperature in the considered area. We studied the evolution of these parameters over time week after week, measuring the maximum recorded difference and its correlation to acute radiation dermatitis intensity. RESULTS: Sixty-four consecutive patients were included. For all patients, we noticed an increase of temperature during the course of radiotherapy. Difference in maximum, minimum and average temperature was higher between the two breasts of patients with a radiation-induced dermatitis grade 2 or above compared to patients with no or mild dermatitis. Higher temperatures were also significantly associated with an increased sensation of discomfort, as recorded by questionnaire (P<0.05). CONCLUSION: As expected from the inflammatory phenomena involved in radiation-induced dermatitis, a noticeable increase in temperature during the course of radiotherapy was seen in all patients. Furthermore, high-grade radiation-induced dermatitis was strongly associated with an additional increase in local temperature, which is probably linked to the intense inflammatory reaction. Lastly, with a 1.4°C threshold set beforehand, it is possible to anticipate the occurrence of radiation-induced dermatitis, with interesting positive and negative predictive values of 70% and 77%, respectively in our population. We note that these results need to be confirmed in a dedicated study.

Effects of a pulsed light-induced stress on Enterococcus faecalis.

AIMS: Pulsed light (PL) technology is a surface decontamination process that can be used on food, packaging or water. PL efficiency may be limited by its low degree of penetration or because of a shadow effect. In these cases, surviving bacteria will be able to perceive PL as a stress. Such a stress was mimicked using low transmitted energy conditions, and its effects were investigated on the highly environmental adaptable bacterium Enterococcus faecalis V583. METHODS AND RESULTS: In these laboratory conditions, a complete decontamination of the artificially inoculated medium was performed using energy doses as low as 1.8 J cm(-2) , while a treatment of 0.5, 1 and 1.2 J cm(-2) led to a 2.2, 6 and 7-log(10) CFU ml(-1) reduction in the initial bacterial population, respectively. Application of a 0.5 J cm(-2) pretreatment allowed the bacteria to resist more efficiently a 1.2 J cm(-2) subsequent PL dose. This 0.5 J cm(-2) treatment increased the bacterial mutation frequency and affected the abundance of 19 proteins as revealed by a global proteome analysis. CONCLUSIONS: Enterococcus faecalis is able to adapt to a PL treatment, providing a molecular response to low-energy PL dose, leading to enhanced resistance to a subsequent treatment and increasing the mutation frequency. SIGNIFICANCE AND IMPACT OF THE STUDY: This study gives further insights on Ent. faecalis capacities to adapt and to resist to stress.

Adaptation of Pseudomonas aeruginosa to a pulsed light-induced stress.

AIMS: Pulsed light (PL) technology is an efficient surface decontamination process. Used in low transmitted energy conditions, PL induces a stress that can be perceived by bacteria. The effect of such a PL stress was investigated on the highly environmental adaptable germ Pseudomonas aeruginosa PAO1. METHODS AND RESULTS: Pulses of transmitted energy (fluence) reaching 1·8Jcm(-2) can kill 10(9) bacteria. Application of a lower sublethal PL dose allowed the bacteria to resist and survive more efficiently to a subsequent dose of PL. This sublethal dose was not increasing the mutation frequency of Ps. aeruginosa, but altered the abundance of 15 proteins as revealed by a global proteome analysis, including stress-induced proteins, phage-related proteins, energy and carbon metabolisms, cell motility, and transcription and translation regulators. CONCLUSIONS: A response to a low-energy PL dose takes place in Ps. aeruginosa, reducing the energy conversion systems, while increasing transcription and translation processes to produce proteins involved in chaperone mechanisms and phage-related proteins, probably to protect the bacterium against a new PL-induced stress. SIGNIFICANCE AND IMPACT OF THE STUDY: Taken together, these results suggest that a low-energy PL dose is sufficient to provoke adaptation of Ps. aeruginosa, leading to enhancing its resistance to a subsequent lethal treatment.