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INTRODUCTION: Three-dimensional conformal radiation therapy has become one of the basic components of multidisciplinary treatment for head and neck cancer. Generally, patients with squamous-cell carcinoma of the head and neck receive cisplatin-based chemoradiation. AIMS: In the current project, the goal was to assess 3D-CRT with cisplatin-induced acute side effects (dermatitis plus xerostomia) among head and neck cancer patients. METHODOLOGY: This descriptive case series was held at the Institute of Nuclear Medicine and Oncology, Lahore, Pakistan, with an enrollment of 106 head and neck cancer patients following the hospital's ethical approval. All patients received 3D-CRT with concurrent cisplatin chemotherapy according to the oncology treatment protocol at the Institute of Nuclear Medicine and Oncology. The evaluation of enrolled patients was done during treatment at a weekly interval and at one-month post-radiation. Stage 3 patients (17.9%) received chemo-radiation therapy with 40 mg/m2 cisplatin once weekly for seven weeks. All patients received 70 grays in 35 fractions with two grays per fraction over the course of seven weeks following a standard protocol. All enrolled cases had biopsy-proven squamous cell carcinoma of the head and neck. IBM Corp. Released 2015. IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp. analyzed the data. Chi-square and Fisher's exact tests were applied, while a p-value ≤ 0.05 was taken as statistically significant. RESULTS: All patients developed acute skin changes (dermatitis plus xerostomia) as a side effect of radiation therapy, with cisplatin having different grades during treatment until seven weeks. However, these changes improved and became less severe in terms of grade after one month of post-treatment among all patients. CONCLUSION: It was concluded that 3D-CRT was associated with dermatitis and xerostomia during and immediately after follow-up, even though the treatment response was good. However, clinical signs and symptoms improved, indicating that radiation therapy is a relatively safe treatment modality among cancer patients. Moreover, 40 mg/m2 cisplatin once weekly for seven weeks resulted in better loco-regional control and survival among advanced-stage head and neck cancer patients as a part of treatment. Although, higher doses of cisplatin (100 mg/m2 ) every three weeks have more harmful acute side effects and delay treatment for patients due to poor compliance.

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BACKGROUND: The established standard treatment for locally advanced head and neck squamous cell carcinoma is concurrent chemoradiotherapy, but the optimum radiotherapy schedule for best disease control and acceptable toxicity is still evolving. Tumor control probability decreases with each day's prolongation of treatment time. Shortening the overall treatment time of radiation by pure accelerated radiotherapy may be a good option. MATERIAL AND METHODS: One hundred and sixty-five patients with histopathologically proven squamous cell carcinoma of the head and neck were included in the study and were assigned into two groups from January 2017 to June 2019. The total dose of 70 Gy was given, 2 Gy/fraction/day. Treatment was given five days a week (conventional radiotherapy) and six days a week (pure accelerated radiotherapy). Both groups received weekly concurrent injections of cisplatin. RESULTS:  The stage (p=0.006) and fractionation of radiation (p=0.018) were the independent factors affecting disease-free survival (DFS). There was a statistically significant difference (p=0.019) in the recurrence of patients in different fractionation schedules. The median DFS was 39 months with a 95% CI of 31.44 - 46.55. One- and three-year DFS was 51% and 8.5% respectively in the five fractions/week schedule arm while 54.5% and 9.5% respectively in the six fractions/week schedule group. CONCLUSION: Pure accelerated radiotherapy is more efficacious in terms of disease control with comparable mildly increased acute side effects.

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Hypersensitivity reactions induced by nonionic iodine contrast media sometimes occur and can be life threatening. However, independent factors affecting their occurrence remain to be fully established. Therefore, the purpose of this study was to clarify independent factors affecting the occurrence of hypersensitivity reactions induced by nonionic iodine contrast media. Patients who received nonionic iodine contrast media at Keiyu Hospital from April 2014 to December 2019 were included. The adjusted odds ratio (OR) and 95% confidence interval (CI) for factors affecting hypersensitivity reactions induced by contrast media were calculated by logistic regression analysis. The multiple imputation method was used to impute missing data. Hypersensitivity reactions occurred in 0.72% (163 cases) of 22,695 cases enrolled in this study. In univariate analysis, 10 variables met the criteria of P < .05 and proportion of missing data <50%. In multivariate analysis, age (OR, 0.98; 95% CI, 0.97-0.99), outpatient status (OR, 2.08; 95% CI, 1.20-3.60), contrast medium iodine content (OR, 1.02; 95% CI, 1.01-1.04), history of drug allergy (OR, 2.41; 95% CI, 1.50-3.88), and asthma (OR, 17.4; 95% CI, 7.53-40.1) were identified as independent factors affecting contrast media-induced hypersensitivity reactions. Among these factors, history of drug allergy and asthma appear to be clinically relevant and reliable due to their high OR and plausible biological mechanisms, but the other three factors require further validation.

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Asma , Hipersensibilidad a las Drogas , Hipersensibilidad , Yodo , Humanos , Yodo/efectos adversos , Medios de Contraste/efectos adversos , Hipersensibilidad a las Drogas/epidemiología , Hipersensibilidad a las Drogas/etiología

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BACKGROUND: Optimal radiation therapy (RT) fractionation in early prostate cancer in elderly patients is controversial. We compared acute toxicities of fractionation schedules: 78/2 Gy, 60/3 Gy and 36.25/7.25 Gy, in this single-centre study. We also evaluated the effect of the rectal immobilization system Rectafix on quality of life (QoL). PATIENTS AND METHODS: Seventy-three patients with one or two intermediate prostate cancer risk factors according to National Comprehensive Cancer Network criteria were recruited. Twenty-one patients were treated with 78/2 Gy and 60/3 Gy, and 31 patients with 36.25/7.25 Gy. Their QoL data were assessed with regard to genitourinary, gastrointestinal and sexual wellbeing at the beginning and end of RT and at 3 months after treatment. Rectafix was used in the 78/2 Gy and 60/3 Gy groups. RESULTS: There were no statistically significant QoL differences in between the treatment groups 3 months after RT. The 78/2 Gy group had significantly increased bowel movements between baseline and 3 months after RT (p=0.036). At 3 months after RT, this group also had significantly more erectile dysfunction than the 60/3 Gy group (p=0.025). At the end of RT, the 78/2 Gy group had more symptoms than the 36.25/7.25 Gy group. Rectafix did not reduce acute toxicities in the 78/2 Gy or 60/3 Gy groups. CONCLUSION: Treatment with the 78/2 Gy schedule is no longer to be recommended due to its increased acute toxicity compared to treatments of 60/3 Gy and 36.25/7.25 Gy. The shortest schedule of 36.25 Gy in five fractions seems to be a convenient treatment option with tolerable acute toxicity.

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Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Neoplasias de la Próstata , Anciano , Fraccionamiento de la Dosis de Radiación , Humanos , Masculino , Neoplasias de la Próstata/radioterapia , Calidad de Vida , Recto/efectos de la radiación

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Syringe aspiration when vaccinating intramuscularly was not recommended before the pandemic due to the lack of conclusive evidence that it provides any benefit. However, in vivo evidence suggests that intravenous injection of mRNA vaccine can potentially lead to myocarditis, while introducing adenoviral vector to bloodstream can possibly result in thrombocytopenia and coagulopathy. These rare reactions were recorded in humans following the administration of the COVID-19 vaccines. Although the syringe aspiration may increase the level of pain at the injection site, it represents a simple technique to decrease the risk of vaccine introduction into the vascular system and potentially decrease the risk of severe reactions to mRNA and adenoviral vaccines. We are of the opinion that this cannot be disregarded if one considers that the COVID-19 vaccines will continue to be administrated globally in the form of initial and booster doses. Therefore, the aspiration when giving mRNA and adenoviral vaccines appears to be fully in line with the precautionary principle.

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COVID-19 , Miocarditis , Humanos , Vacunas contra la COVID-19/efectos adversos , COVID-19/prevención & control , Pandemias , ARN Mensajero

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PURPOSE: To report applicator insertion-related acute side effects during brachytherapy (BT) procedure for cervical cancer patients. MATERIALS AND METHODS: Between November 2017 and December 2019, 407 BT fractions were performed in 125 patients with locally advanced cervical cancer. Acute side effects recorded comprised anesthesia-related side effects, mechanical-related side effects and infection, whose frequency and degree were recorded. Pain was assessed using numeric rating scale; vaginal bleeding volume was counted by weighing gauze pieces used in packing. The BT procedure comprised eight stages: anesthesia, applicator insertion, image acquisition, transport, waiting for treatment, dose delivery, applicator removal, and removed which denoted 0.5-12.0 h period after removal, with time of each stage recorded. Factors influencing acute side effects were assessed by Spearman correlation and Mann-Whitney U test. RESULTS: The most common acute side effect was pain, followed by vaginal bleeding. The mean scores for pain were highest during removal time, 4.9 ± 1.6 points. The mean vaginal bleeding volume was 44.4 ml during removal time. Mean total procedure time was 218.8 (175-336) min, having positive relationship with frequency of acute side effects. The total procedure time with acute side effects was longer than that without acute side effects. The longest procedure time was waiting time, 113.0 (91.0-132.0) min. More needles generated higher pain scores and larger volume of vaginal bleeding. CONCLUSION: Pain and vaginal bleeding were the most common acute side effects, especially during removal time, which physicians should focus on. Shortening patients' waiting time helps to reduce the total procedure time, thus, reduce acute side effects. While meeting dose requirement, less needles are helpful to reduce acute side effects.

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INTRODUCTION/AIMS: Oxaliplatin often causes acute or chronic peripheral neuropathy in patients with an intestinal or pancreatic tumor, but in-depth insights in its influence on quality of life (QoL) are lacking. We explored the influence of acute oxaliplatin-induced peripheral neuropathy (OIPN) on daily QoL in these patients. METHODS: We performed semistructured interviews with a purposive sample of patients receiving oxaliplatin and possibly experiencing acute OIPN. Interviews were audio-recorded, transcribed verbatim, and coded by two researchers. Data were analyzed by using the constant comparative method for content analysis with ATLAS.ti software. RESULTS: After nine patients, saturation took place. In total, 11 patients were interviewed. Four themes were extracted from the data: (1) adverse effects, (2) physical (un)well-being, (3) emotional aspects, and (4) treatment aspects. All participants were suffering from acute OIPN to a certain extent, leading to restrictions in daily activities such as household chores, but also to a decrease in mobility and independency. Other adverse effects such as general malaise and gastrointestinal side effects also influenced the participants' well-being, as did the diagnosis and prognosis of their disease. CONCLUSION: Acute OIPN, together with other side effects of chemotherapeutic treatment and the difficulties that come with the diagnosis of cancer and its prognosis, largely influences patients' daily QoL. Managing expectations (by patient education) seems important.

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Antineoplásicos , Enfermedades del Sistema Nervioso Periférico , Actividades Cotidianas , Antineoplásicos/efectos adversos , Humanos , Oxaliplatino/efectos adversos , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Calidad de Vida

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BACKGROUND: Radiotherapy treatment for cervical cancer (CC) often induces side effects, including inflammation, dryness, dyspareunia. Considering its key role in the healing process, hyaluronic acid (HA) could be useful for the completion of radiotherapy. OBJECTIVES: The aim of this work was to evaluate the ability of HA to reduce the onset of side effects due to radiotherapy. MATERIALS AND METHODS: In total, 180 women undergoing radiotherapy were randomized into two arms: controls and those treated with vaginal suppositories containing low-molecular-weight HA from day 1 of radiotherapy. The study lasted 5 weeks and was characterized by three visits: at baseline (T0), 15 days later (T1), and at the end of the radiotherapy cycle (T2). The onset of side effects, pain, safety, efficacy, acceptability of treatment, and compliance to the therapy were evaluated. RESULTS: Patients in the control arm reported the onset and worsening of all symptoms with a moderate or severe grade at T2, whereas in the treatment arm almost 90% of patients reported the absence of symptoms or a mild grade. All patients in the treatment arm referred a lower intensity of pain on a visual analog scale compared with the control arm at T2 (6.85 ± 0.94 vs. 1.88 ± 1.02). CONCLUSIONS: HA was able to help vaginal mucosa healing during radiotherapy in patients with CC.

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Ácido Hialurónico/administración & dosificación , Neoplasias del Cuello Uterino/radioterapia , Enfermedades Vaginales/prevención & control , Adulto , Anciano , Femenino , Humanos , Persona de Mediana Edad , Estadificación de Neoplasias , Traumatismos por Radiación/prevención & control , Radioterapia Adyuvante , Neoplasias del Cuello Uterino/terapia , Enfermedades Vaginales/etiología

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BACKGROUND: The limited availability of proton beam therapy (PBT) requires individual treatment selection strategies, such as based on normal tissue complication probability (NTCP). We developed and externally validated NTCP models for common acute side-effects following PBT in brain tumour patients in effort to provide guidance on optimising patient quality of life. METHODS: An exploration cohort including 113 adult brain tumour patients who underwent PBT was investigated for the following endpoints: alopecia, scalp erythema, headache, fatigue and nausea. Dose-volume parameters of associated normal tissues were used for logistic regression modelling. Statistically significant parameters showing high area under the receiver operating characteristic curve (AUC) values in internal cross-validation were externally validated on two cohorts of 71 and 96 patients, respectively. RESULTS: Statistically significant correlations of dose-volume parameters of the skin for erythema and alopecia were found. In internal cross-validation, the following prognostic parameters were selected: V35Gy (absolute volume receiving 35 Gy) for erythema grade ≥1, D2% (dose to 2% of the volume) for alopecia grade ≥1 and D5% for alopecia grade ≥2. Validation was successful for both cohorts with AUC >0.75. A bivariable model for fatigue grade ≥1 could not be validated externally. No correlations of dose-volume parameters of the brain were seen for headache or nausea. CONCLUSION: We developed and successfully validated NTCP models for scalp erythema and alopecia in primary brain tumour patients treated with PBT.

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Neoplasias Encefálicas/radioterapia , Terapia de Protones/efectos adversos , Traumatismos por Radiación/etiología , Enfermedad Aguda , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Encefálicas/psicología , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Probabilidad , Calidad de Vida , Adulto Joven

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Normal tissue reactions are therapy limiting factor for the effectiveness of the radiotherapy in cancer patients. DNA repair and apoptosis are estimated to be critical players of adverse effects in response to radiotherapy. Our aim was to define the association of DNA repair (ERCC1 and XPC) and apoptotic (BCL2, CASP3 and NFKB1) gene expression, DNA damage levels, apoptosis changes and DNA repair gene variations with the risk of acute side effects in breast cancer patients. The study included 100 women with newly diagnosed breast cancer; an experimental case group (n=50) with acute side effects and the control group (n=50) without side effects. Gene expression was analyzed by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). Micronucleus (MN) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) assays were performed to compare the DNA damage levels. Apoptosis was examined by TDT-mediated dUTP-biotin nick end-labeling (TUNEL) staining. ERCC1 rs3212986 and XPC rs3731055 polymorphisms were genotyped by real-time PCR technique. No significantly correlation of DNA repair and apoptosis gene expression and DNA damage levels with acute side effects in response to radiotherapy. Also, there was no association between apoptosis levels and acute effects. ERCC1 rs3212986 CC genotype showed a protective effect against radiotherapy-induced acute reactions (p<0.001; OR: 0.21; 95% CI= 0.08-0.52). Our results suggest that apoptosis and DNA damage levels are not associated with acute radiosensitivity. DNA repair may affect the risk of acute reactions. Further studies are needed to validate the current findings.

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Neoplasias de la Mama/radioterapia , Carcinoma Ductal/radioterapia , Carcinoma Lobular/radioterapia , Proteínas de Unión al ADN/genética , Endonucleasas/genética , Rayos gamma/efectos adversos , Regulación Neoplásica de la Expresión Génica , Piel/efectos de la radiación , 8-Hidroxi-2'-Desoxicoguanosina , Adulto , Apoptosis/efectos de la radiación , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Carcinoma Ductal/genética , Carcinoma Ductal/metabolismo , Carcinoma Ductal/patología , Carcinoma Lobular/genética , Carcinoma Lobular/metabolismo , Carcinoma Lobular/patología , Caspasa 3/genética , Caspasa 3/metabolismo , Fragmentación del ADN/efectos de la radiación , Reparación del ADN/efectos de la radiación , Proteínas de Unión al ADN/metabolismo , Desoxiguanosina/análogos & derivados , Desoxiguanosina/metabolismo , Endonucleasas/metabolismo , Femenino , Humanos , Etiquetado Corte-Fin in Situ , Pruebas de Micronúcleos , Persona de Mediana Edad , Subunidad p50 de NF-kappa B/genética , Subunidad p50 de NF-kappa B/metabolismo , Polimorfismo de Nucleótido Simple , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Tolerancia a Radiación , Transducción de Señal , Piel/metabolismo , Piel/patología

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DNA repair plays a critical role in response to ionizing radiation (IR) and developing of radiotherapy induced normal tissue reactions. In our study, we investigated the association of radiotherapy related acute side effects, with X-ray repair cross complementing group 1 (XRCC1) and Poly (ADP-ribose) polymerase 1 (PARP1) DNA repair gene expression levels, their changes in protein expression and DNA damage levels in breast cancer patients. The study included 40 women with newly diagnosed breast cancer; an experimental case group (n=20) with acute side effects and the control group (n=20) without side effects. For gene and protein expression analysis, lymphocytes were cultured for 72 h and followed by in vitro 2 Gray (Gy) gamma-irradiation. For detection of DNA damage levels, lymphocytes were irradiated with in vitro 2 Gy gamma-rays and followed by incubation for 72 h. XRCC1 mRNA and protein expression levels were significantly higher in controls than in experimental cases (P=0.020). In terms of DNA damage levels, an increased frequency of micronucleus (MN) was observed in experimental cases versus controls, but this association was not significant (P=0.206). We also observed a significant negative correlation between MN frequency and XRCC1 protein levels in experimental (r=-0.469, P=0.037) vs control (r=-0.734, P<0.001). Our results suggested that decreased XRCC1 expression levels might be associated with the increased risk of therapeutic IR-related acute side effects in patients with breast cancer.

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Neoplasias de la Mama/radioterapia , Proteínas de Unión al ADN/biosíntesis , Predisposición Genética a la Enfermedad , Poli(ADP-Ribosa) Polimerasas/biosíntesis , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Daño del ADN/efectos de la radiación , Reparación del ADN/efectos de la radiación , Proteínas de Unión al ADN/genética , Femenino , Rayos gamma/efectos adversos , Regulación Neoplásica de la Expresión Génica , Genotipo , Humanos , Poli(ADP-Ribosa) Polimerasa-1 , Poli(ADP-Ribosa) Polimerasas/genética , Radioterapia/efectos adversos , Proteína 1 de Reparación por Escisión del Grupo de Complementación Cruzada de las Lesiones por Rayos X

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Objective To analyze the difference of dosimetry and evaluate clinical efficacy and acute toxicity reaction between RapidArc and fixed gantry angle dynamic intensity modulated radiotherapy (IMRT) in advanced cervical carcinoma.Methods A total of 43 patients with locally advanced cervical cancer were studied,including 22 patients treated with RapidArc and 21 patients with IMRT.All plans were prescribed 50.4 Gy in 28 fractions.The conformity index and homogeneity index of the targets,the monitor units(MUs) and delivery time were compared.Incidence of acute intestinal and bladder side effects and rates of efficacy were calculated.Results The conformity index of RapidArc was better compared to IMRT.The V40 and V50 of bladder and V30,V40 and V50 of rectum planned by RapidArc was significantly lower than that by IMRT(t =-2.386,-2.397,P ＜0.05;t =-5.525,-2.883,-2.686,P ＜0.05).The mean dose of femoral head planned by RapidArc was also significantly lower (t =-2.395,P ＜ 0.05).For RapidArc,mean MU and treatment time were reduced by 53.15％,and 62.14％,respectively.There was no difference in the incidence of acute intestinal and bladder toxicity and rates of complete remission and efficacy between the two groups.Conclusions In dosimetric analysis,RapidArc showed advantage in protecting organs at risk and reducing treatment time in radical radiotherapy for locally advanced cervical carcinoma.

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Objective To compare the planning quality and acute toxicity between RapidArc and fixed gantry angle dynamic intensity modulated radiotherapy (IMRT) in the postoperative radiotherapy for cervical cancer patients.Methods All 35 patients with cervical cancer who had received postoperative radiotherapy were studied,including 17 patients with RapidArc and 18 patients with IMRT.All plans were prescribed 50 Gy in 25 fractions.The dose-volume histogram data,the conformity index and homogeneity index of the targets,the monitor units (MUs) and delivery time were compared.During the treatment,the incidence of acute intestinal and bladder side effects were also compared.Results Compared to IMRT,the conformity index of RapidArc was better(t =3.13,P ＜ 0.05),but the homogeneity index was slightly worse (t =-4.25,P ＜ 0.05).The V20 and V30 of femoral head planned by RapidArc was significantly lower than that by IMRT (t =2.56,2.34,P ＜ 0.05).The mean MU for RapidArc was reduced by 52.1％ compared with IMRT.The mean treatment time for RapidArc was decreased by 46.8％ compared with IMRT.There was no difference in the incidence of acute intestinal and bladder toxicity between the two groups.Conclusion For patients with cervical cancer who need prophylactic postoperative radiotherapy,both RapidArc and IMRT plan can achieve equal target coverage and organs at risk(OAR) sparing.There is no significant difference in dosimetric parameters and acute toxicity between the two groups.Compared with IMRT,RapidArc plan has fewer MUs and less treatment time and significantly improves the treatment efficiency.

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ObjectiveTo discuss dosimetric characteristics of an intensity-modulated radiotherapy (IMRT) technique for treating the chest wall and regional nodes as an integrated volume after modified radical mastectomy ( MRM ),and observe acute side-effects following irradiation.Methods From June 2009 to August 2010,75 patients were randomly enrolled.Of these,41 had left-sided breast cancer.Each eligible patient had a planning CT in treatment position,on which the chest wall,supraclavicular,and infraclavicular nodes,+/-internal mammary region,were contoured as an integrated volume.A muhi-beam IMRT plan was designed with the target either as a whole or two segments divided at below the clavicle head.A dose of 50 Gy in 25 fractions was prescribed to cover at least 90％ of the PTV.Internal mammary region was included in 31 cases.Dose volume histograms were used to evaluate the IMRT plans.The acute side effects were followed up regularly during and after irradiation.The independent two-sample t-test was used to compare the dosimetric parameters between integrated and segmented plans.ResultsPlanning design was completed for all patients,including 55 integrated and 20 segmented plans,with median number of beams of 8.The conformity index and homogeneity index was 1.43 ± 0.15 and 0.14 ± 0.02,respectively.Patients with internal mammary region included in PTV had higher homogeneity index PT.The percent volume of PTV receiving ＞ 110％ prescription dose was ＜ 5％.None of the dose constraints to normal structures was violated.There were statistically significant differences in the means of dosimetric parameters of PTV,such as Dmax,DmeanV107％,and V110％,between integrated and segmented plans (t=2.19 -2.53,P=0.013-0.031 ).≥ grade 2 radiation dermatitis was identified in 3 2 patients ( grade 2 in 2 2 patients,grade 3 in 10 patients ),mostly occurred within 1 - 2 weeks after treatment.The sites of moist desquamation were anterior axillary fold (27/37) and chest wall (10/37).Only 2 patients developed grade 2 radiation pneumonitis.Conclusions The IMRT technique applied after MRM with integrated locoregional target volume is dosimetrically feasible,and the treatment was proved to be well-tolerated by most patients.

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A 60-year-old woman with breast cancer metastatic to the bones experienced no adverse skin reaction at the lumbar spine after a single 8-Gy photon-beam fraction prescribed to a depth of 5 cm. However, a subsequent treatment to the thoracic spine using the same dose, fractionation, and technique resulted in skin erythema and permanent hyperpigmentation. After careful investigation, no differences were identified in her concurrent use of possibly radiosensitizing medications during the various radiotherapy treatments nor in possible errors of treatment planning and radiation delivery. To our knowledge, this is the first case report to document that, with similar medications, a previous skin response to a given radiotherapy dose, fraction, and technique may not be predictive of subsequent skin response to similar radiotherapy.