Objective(s): Radiotherapy is one of the most effective modalities of cancer therapy, but clinical responses of individual patients varies considerably. To enhance treatment efficiency it is essential to implement an individual-based treatment. The aim of present study was to identify the mechanism of intrinsic apoptosis pathway on radiosensitivity and normal tissue complications caused by the radiotherapy. Materials and Methods: Peripheral blood mononuclear cells from ten breast cancer patients were exposed to 6MV X-rays to deliver 1 and 2 Gy. Expression levels of Bax, Bcl-2, and Bax/Bcl-2 ratio were examined by relative quantitative RT-PCR. All the patients received similar tangential irradiation of the whole breast and conventional fractionation. Skin dosimetry was done by GAFChromic EBT-3 film and clinical radiosensitivity was determined using the acute reactions to radiotherapy of the skin according to Radiation Therapy Oncology Group score. All statistical analyses were performed using GraphPad Prism, version 7.01. Results: In the in-vitro experiment, Bax and Bax/Bcl-2 ratios were significantly increased with 1 and 2 Gy doses (PP 0.05 for all patients). Conclusion: Significant correlation between Bax/Bcl-2 ratio determined before radiation therapy and clinical response in the patients, can be used as a biomarker to identify radiosensitive individuals. However, further studies are required to validate radiation-induced apoptotic biomarkers.

https://ijbms.mums.ac.ir/article_10207_78e0a49a09ff80be7500e1286a62f85e.pdf

Bax/Bcl-2 expression ratio in prediction of response to breast cancer radiotherapy.

Background: Chemotherapy, as a systemic therapy, is one of the most effective modalities for cancer treatment. However, the use of chemotherapeutic drugs in patients withÂ breast cancer can lead to thyroid dysfunction. This systematic review summarizes the available data on thyroid function following breast cancer chemotherapy. Methods: To illuminate the thyroid toxicities induced by different chemotherapy regimens in patients with breast cancer, a systematic search was done in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline in Scopus, Embase, PubMed and Web of Science electronic databases up to December 2018. On the basis of a set of prespecified inclusion and exclusion criteria, eight eligible articles providing data on thyroid function following chemotherapy in patients with breast cancer were included in the study. Results: According to the obtained results, it was found that for most cases, the levels of triiodothyronine (T3), free T3 (FT3), thyroxin (T4) and free T4 (FT4) hormones decrease following breast cancer chemotherapy regimens used in these eligible studies. However, alteration of thyroid-stimulating hormone (TSH) level after breast cancer chemotherapy was not clear. Conclusion: The findings showed that thyroid function and TSH hormone level can change in patients withÂ breast cancer receiving different chemotherapy regimens. Â© 2019 Wiley Periodicals, Inc.

Thyroid function following breast cancer chemotherapy: A systematic review

This research aimed to measure the received photon and thermal neutron doses to contralateral breast (CB) in breast cancer radiotherapy for various field sizes in presence of physical and dynamic wedges. The measurement of photon and thermal neutron doses was carried out on right breast region of RANDO phantom (as CB) for 18 MV photon beams. The dose measurements were performed by thermoluminescent dosimeter chips. These measurements obtained for various field sizes in presence of physical and dynamic wedges. The findings of this study showed that the received doses (both of the photon and thermal neutron) to CB in presence of physical wedge for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes were 5.92, 6.36 and 6.77% of the prescribed dose, respectively as well as for dynamic wedge were 2.92, 4.63 and 5.60% of the prescribed dose, respectively. The results showed that the received photon and thermal neutron doses to CB increase with increment of field sizes. The received photon and thermal neutron doses to CB in presence of physical wedge were more than dynamic wedge. According to obtained findings, it is suggested that using a dynamic wedge is preferable than physical wedge, especially for medial tangential field.

Measurement of the contralateral breast photon and thermal neutron doses in breast cancer radiotherapy: a comparison between physical and dynamic wedges.

To evaluate the relationships among patient characteristics, irradiation treatment planning parameters, and treatment toxicity of acute radiation dermatitis (RD) after breast hybrid intensity modulation radiation therapy (IMRT). The study cohort consisted of 95 breast cancer patients treated with hybrid IMRT. RD grade ≥2 (2+) toxicity was defined as clinically significant. Patient characteristics and the irradiation treatment planning parameters were used as the initial candidate factors. Prognostic factors were identified using the least absolute shrinkage and selection operator (LASSO)-based normal tissue complication probability (NTCP) model. A univariate cut-off dose NTCP model was developed to find the dose-volume limitation. Fifty-two (54.7%) of ninety-five patients experienced acute RD grade 2+ toxicity. The volume of skin receiving a dose >35 Gy (V35) was the most significant dosimetric predictor associated with RD grade 2+ toxicity. The NTCP model parameters for V35Gy were TV50 = 85.7 mL and γ50 = 0.77, where TV50 was defined as the volume corresponding to a 50% incidence of complications, and γ50 was the normalized slope of the volume-response curve. Additional potential predictive patient characteristics were energy and surgery, but the results were not statistically significant. To ensure a better quality of life and compliance for breast hybrid IMRT patients, the skin volume receiving a dose >35 Gy should be limited to 35 Gy should follow sparing tolerance and the inherent patient characteristics should be considered.

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Relationships among patient characteristics, irradiation treatment planning parameters, and treatment toxicity of acute radiation dermatitis after breast hybrid intensity modulation radiation therapy.

Aim: The aim of this study was to measure entrance skin dose (ESD) on the breast of patients who had undergone radiotherapy following surgery, in the presence and absence of bolus. Materials and Methods: In this study, the ESD on the breast of 22 female patients was measured using thermoluminescent dosimeter-100 chips. For each patient, the ESD was measured 3 times (once without bolus and twice using bolus). The bolus types used in this study include super flab and wax. Results: The average ESDs on the breast of patients (from both medial and lateral tangential fields) in the presence of the super flab bolus and absence of bolus were 225.8 and 148.17 cGy, respectively, that when using the bolus, around 52% increasing in ESD was observed. The results showed a significant relationship between the ESD on the breast of patients and bolus types (P = 0.002); in addition, correlation coefficient between the two boluses (super flab and wax) was 0.615 (r = 0.615). Conclusion: When using the bolus in postmastectomy irradiation, it is noted that in dose delivery to the chest wall, surgical scar or skin of the treated region should be considered. The use of the bolus as a substance that increases of the skin dose can sometimes cause an excessive increase in skin dose that may cause severe skin reactions and underdosing of underlying tissues. Furthermore, using wax bolus in regions that do not require a lot of shaping of bolus is affordable.

A comparison between skin dose of breast cancer patients at the breast region, measured by thermoluminescent dosimeter in the presence and absence of bolus

Introduction The first medical intervention for many breast cancer patients is breast conserving surgery (BCS) and/or modified radical mastectomy (MRM). Most of these patients undergo radiation therapy, following surgery. The most common side-effect of breast radiotherapy is skin damage. In the present study, the severity of acute skin changes and the underlying causes were investigated in patients undergoing BCS and radiotherapy. Materials and Methods This prospective, cohort study was performed on 31 female patients, undergoing breast surgery therapy at Shahid Rajaie Babolsar Radiotherapy Center from September 2011 to July 2012. A questionnaire was designed, including the patient’s characteristics, details of radiotherapy technique, and skin damage; the questionnaire was completed for each patient. The obtained results were analysed by performing ANOVA and Fisher's exact tests. Complications were graded using the radiation therapy oncology group (RTOG) scale. Results Grade 0 or 4 of skin damage was observed in none of the patients. Among the evaluated patients, 58%, 35.5%, and 6.5% of the patients had grade 1, grade 2, and grade 3 of skin damage, respectively. There was no statistically significant relationship between regional skin burns and factors such as average tangential field size, internal mammary field, chemotherapy, prior history of diseases, tamoxifen use, previous radiotherapy in breast area, or skin type (p>0.05). However, there was a significant relationship between skin burns and presence of supraclavicular field (p=0.05). Conclusion Considering the significant relationship between skin burn and supraclavicular field, special attention needs to be paid to factors affecting the treatment planning of supraclavicular field such as field size and photon energy.

http://ijmp.mums.ac.ir/article_3568_87ce7e79549d61eb0eb0515cd94739d7.pdf

Navid Nekoui

Papers

Skin Reaction in Radiation Therapy for Breast Cancer