A modelled comparison of the effects of using different ways to compensate for missed treatment days in radiotherapy

Investigating Predictive Factors of Dysphagia and Treatment Prolongation in Patients with Oral Cavity or Oropharyngeal Cancer Receiving Radiation Therapy Concurrently with Chemotherapy

Radiation therapy (RT) treatment for head and neck cancer has been associated with dysphagia manifestation leading to worse outcomes and decrease in life quality. In this study, we investigated factors leading to dysphagia and treatment prolongation in patients with primaries arising from oral cavity or oropharynx that were submitted to radiation therapy concurrently with chemotherapy. The records of patients with oral cavity or oropharyngeal cancer that received RT treatment to the primary and bilateral neck lymph nodes concurrently with chemotherapy were retrospectively reviewed. Logistic regression models were used to analyze the potential correlation between explanatory variables and the primary (dysphagia ≥ 2) and secondary (prolongation of total treatment duration ≥ 7 days) outcomes of interest. The Toxicity Criteria of the Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC) were used to evaluate dysphagia. A total of 160 patients were included in the study. Age mean was 63.31 (SD = 8.24). Dysphagia grade ≥ 2 was observed in 76 (47.5%) patients, while 32 (20%) experienced treatment prolongation ≥ 7 days. The logistic regression analysis showed that the volume in the primary site of disease that received dose ≥ 60 Gy (≥118.75 cc, p < 0.001, (OR = 8.43, 95% CI [3.51-20.26]) and mean dose to the pharyngeal constrictor muscles > 40.6 Gy (p < 0.001, OR = 11.58, 95% CI [4.84-27.71]) were significantly associated with dysphagia grade ≥ 2. Treatment prolongation ≥ 7 days was predicted by higher age (p = 0.007, OR = 1.079, 95% CI [1.021-1.140]) and development of grade ≥ 2 dysphagia (p = 0.005, OR = 4.02, 95% CI [1.53-10.53]). In patients with oral cavity or oropharyngeal cancer that receive bilateral neck irradiation concurrently with chemotherapy, constrictors mean dose and the volume in the primary site receiving ≥ 60 Gy should be kept below 40.6 Gy and 118.75 cc, respectively, whenever possible. Elderly patients or those that are considered at high risk for dysphagia manifestation are more likely to experience treatment prolongation ≥ 7 days and they should be closely monitored during treatment course for nutritional support and pain management.

Effect of radiotherapy interruption on nasopharyngeal cancer

Nasopharyngeal carcinoma (NPC) is a malignant tumor originating from the epithelial cells of the nasopharynx with a unique geographic distribution, and is particularly prevalent in East and Southeast Asia. Due to its anatomical location, the surgery is difficult to access and the high sensitivity of nasopharyngeal cancer to radiotherapy (RT) makes it the main treatment modality. Radical radiotherapy is the first-line treatment for early-stage nasopharyngeal carcinoma and the cornerstone of multidisciplinary treatment for patients with locally advanced nasopharyngeal carcinoma. Nevertheless, radiotherapy interruption is inevitable as a consequence of unavoidable factors such as public holidays, machine malfunction, patient compliance, and adverse response to treatment, which in turn leads to a reduction in bioactivity and causes sublethal loss of tumor cells to repair. Unirradiated tumor cells are more likely to repopulate at or near their original fastest growth rate during this interval. If no measures are taken after the radiotherapy interruption, such as increasing the dose of radiotherapy and systemic therapy, the tumor is most likely to go uncontrolled and then progress. This review describes the effects of radiotherapy interruption on nasopharyngeal carcinoma, the mechanism of the effect, and explores the measures that can be taken in response to such interruption.

Machine Learning-Based Multiomics Prediction Model for Radiation Pneumonitis

Objective

The study aims to establish and validate an effective CT-based radiation pneumonitis (RP) prediction model using the multiomics method of radiomics and EQD2-based dosiomics.

Materials and Methods

The study performed a retrospective analysis on 91 nonsmall cell lung cancer patients who received radiotherapy from 2019 to 2021 in our hospital. The patients with RP grade ≥1 were labeled as 1, and those with RP grade < 1 were labeled as 0. The whole lung excluding clinical target volume (lung-CTV) was used as the region of interest (ROI). The radiomic and dosiomic features were extracted from the lung-CTV area's image and dose distribution. Besides, the equivalent dose of the 2 Gy fractionated radiation (EQD₂) model was used to convert the physical dose to the isoeffect dose, and then, the EQD2-based dosiomic (eqd-dosiomic) features were extracted from the isoeffect dose distribution. Four machine learning (ML) models, including DVH, radiomics combined with DVH (radio + DVH), radiomics combined with dosiomics (radio + dose), and radiomics combined with eqd-dosiomics (radio + eqdose), were established to construct the prediction model via eleven different classifiers. The fivefold cross-validation was used to complete the classification experiment. The area under the curve (AUC) of the receiver operating characteristics (ROC), accuracy, precision, recall, and F1-score were calculated to assess the performance level of the prediction models.

Results

Compared with the DVH, radio + DVH, and radio + dose model, the value of the training AUC, accuracy, and F1-score of radio + eqdose was higher, and the difference was statistically significant (p < 0.05). Besides, the average value of the precision and recall of radio + eqdose was higher, but the difference was not statistically significant (p > 0.05).

Conclusion

The performance of using the ML-based multiomics method of radiomics and eqd-dosiomics to predict RP is more efficient and effective.

Tumour volume and radiotherapy prolongation in locally advanced head and neck cancer patients treated with radical IMRT

AIMS

The relationship of tumour volume, radiotherapy treatment time and other prognostic factors affecting prognosis was evaluated.

METHODS

184 patients with locally advanced head and neck cancer were treated with radical intensity modulated radiotherapy (IMRT) and compared retrospectively.

RESULTS

In the multivariate analysis the overall survival was dependent on gross tumour volume (GTV), clinical stage (CS), radiotherapy treatment time (RTT) and p16 status. Local control was influenced by GTV, overall RTT and age. DFS was significantly affected by GTV, CS, RTT, p16 status and concomitant chemotherapy (CHT).

CONCLUSIONS

The tumour volume and the radiotherapy treatment time were the most significant prognostic factors with the best outcomes in patients with GTV ≤ 55 cc and RTT ≤ 48 days (mean LC 8.1, DFS 7.1 and OS 6.4 years) and worst outcomes with GTV > 55 cc and RTT >48 days (mean LC 4.4, mean DFS 3.2 and mean OS 2.6 years).

Towards personalised dosimetry in patients with liver malignancy treated with 90Y-SIRT using in vivo-driven radiobiological parameters

BACKGROUND

The prediction of response is one of the major challenges in radiation-based therapies. Although the selection of accurate linear-quadratic model parameters is essential for the estimation of radiation response and treatment outcome, there is a limited knowledge about these radiobiological parameters for liver tumours using radionuclide treatments.

METHODS

The "clinical radiobiological" parameters ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]) for twenty-five patients were derived using the generalised linear-quadratic model, the diagnostic ([¹⁸F] FDG PET/CT) and therapeutic ([⁹⁰Y]-SIR-Spheres PET/CT) images to compute the biological effective dose and tumour control probability (TCP) for each patient.

RESULTS

It was estimated that the values for [Formula: see text] and [Formula: see text] parameters range in ≈ 0.001-1 Gy^-1 and ≈ 1-49 Gy, respectively. We have demonstrated that the time factors, [Formula: see text], [Formula: see text] and [Formula: see text] are the key parameters when evaluating liver malignancy lesional response to [⁹⁰Y]SIR-Spheres treatment. Patients with cholangiocarcinoma have been shown to have the longest average [Formula: see text] (≈ 236 ± 67 d), highest TCP (≈ 53 ± 17%) and total liver lesion glycolysis response ([Formula: see text] ≈ 64%), while patients with metastatic colorectal cancer tumours have the shortest average [Formula: see text] (≈ 129 ± 19 d), lowest TCP (≈ 28 ± 13%) and [Formula: see text] ≈ 8%, respectively.

CONCLUSIONS

Tumours with shorter [Formula: see text] have shown a shorter [Formula: see text] and thus poorer TCP and [Formula: see text]. Therefore, these results suggest for such tumours the [⁹⁰Y]SIR-Spheres will be only effective at higher initial dose rate (e.g.  > 50 Gy/day).

Hypo-fractionated radiotherapy with concurrent chemotherapy for locoregional recurrence of non-small cell lung cancer after complete resection: A prospective, single-arm, phase II study (GASTO-1017)

OBJECTIVES

To explore the efficacy and toxicities of split-course hypo-fractionated radiotherapy with concurrent chemotherapy (HFRT-CHT) with intensity modulated radiotherapy (IMRT) technique in non-small cell lung cancer (NSCLC) patients with postoperative locoregional recurrence (LRR).

MATERIALS AND METHODS

NSCLC patients were eligible if confirmed as LRR disease without distant metastasis after complete resection. HFRT-CHT using IMRT technique was administered with 51 Gy in 17 fractions or 40 Gy in 10 fractions as the first course followed by a break. Patients with no disease progression and no persistent Grade ≥2 toxicities had the second course of 15 Gy in 5 fractions or 28 Gy in 7 fractions as a boost. The primary endpoint was progression-free survival (PFS).

RESULTS

Fifty-eight patients were enrolled and analyzed. With a median follow-up of 23.9 months for all, the 2-year and 3-year PFS rate was 59.7 % and 46.4 %, the 2-year and 3-year OS rate was 72.5 % and 52.2 %, respectively, and a favorable objective response rate of 95.9 % was obtained after the whole courses protocol. Grade 3 acute pneumonitis and esophagitis occurred in 2 (3.4 %) and 7 (12.1 %) patients, and fatal pneumonitis was reported in one case (1.7 %). Exploratory subgroup analysis showed that performance status (PS) (PS 0 vs. 1: 2-year PFS, 88.1 % vs. 46.9 %,P = 0.001; 2-year OS, 100 % vs. 59.4 %, P < 0.001), recurrence site (single vs. multiple: 2-year PFS, 93.8 % vs. 47.4 %, P = 0.008; 2-year OS, 100 % vs. 63.0 %, P = 0.001), and gross tumor volume (GTV) (<50cm³ vs. ≥ 50cm³: 2-year PFS, 70.6 % vs. 46.2 %, P = 0.024; 2-year OS, 85.6 % vs. 57.4 %, P = 0.034) were significantly associated with PFS and OS.

CONCLUSION

Split-course HFRT-CHT with IMRT technique achieved promising disease control and satisfactory survival with moderate toxicities in postoperative LRR of NSCLC. Good PS, a single recurrence site and GTV<50cm³ tended to have prolonged PFS and OS. Early detection of LRR may improve the efficacy of HFRT-CHT.

Prolongation of definitive head and neck cancer radiotherapy: Survival impact and predisposing factors

BACKGROUND AND PURPOSE

To quantify the survival impact of prolongation of definitive radiotherapy (RT) for head and neck cancer in a national, modern cohort, and to identify predictive factors for prolongation.

MATERIALS AND METHODS

The National Cancer Database was queried for adults with non-metastatic cancer of the nasopharynx, oropharynx, larynx, or hypopharynx diagnosed 2004-2015, treated with definitive RT to 66-70 Gy in 30-35 fractions at 2-2.2 Gy per fraction. Multivariable Cox regression and propensity score matching were used to model the survival impact of RT prolongation, adjusting for potential confounders such as age and comorbidity. Predictors of RT prolongation were identified using multivariable multinomial logistic regression.

RESULTS

In total, 36,367 patients were identified. As a continuous variable, RT prolongation increased the relative hazard of death by 2% per day (P < .0001). In the matched cohorts, patients with short (4-8 days) or long prolongation (>8 days) had lower absolute 4-year overall survival by 4% and 12%, respectively (P < .0001), while prolongation of 1-3 days was not significantly adverse. Major predictors of increased risk of prolongation were administration of systemic therapy, baseline comorbidity, lack of private insurance, and tumor/nodal stage. Conversely, higher facility volume was significantly protective, with a 55% lower risk of long prolongation within the topmost quartile (>11.5 patients/year).

CONCLUSION

RT prolongation, especially >8 days, is significantly deleterious. Systemic therapy and facility volume were major predictors. Early identification of patients at increased risk of treatment interruptions may facilitate implementation of preventive measures.

Adaptive time management for patients who have non-small cell lung cancer and underwent definitive radiotherapy: a dosimetric study of different gap duration scenarios

PURPOSE

The purpose of this study was to evaluate the tumor control probability (TCP), normal tissue complication probability (NTCP) and adaptive time management (ATM) in patients who had non-small cell lung cancer (NSCLC) and underwent radiotherapy with same gap length at different treatment weeks.

MATERIAL AND METHODS

Twenty patients' definitive radiotherapy treatments, completed in 6.5 weeks, were evaluated retrospectively. Three different scenarios with gaps in 5 fractions at different weeks of treatment (2nd, 4th, and 6th week) were planned. Three ATM models (biologically effective dose (C_BED), time-dose-fractionation (C_TDF) and in-house developed (C_InH)) were calculated for each scenario. TCP and NTCP were calculated and compared with the dose-volume histogram (DVH) of each model.

RESULTS

TCP was accepted as 100% in uninterrupted treatments. When treatment was interrupted and not compensated with ATM, the highest TCP difference was determined as 23.46% in the 4th week (p<.001). Based on comparisons of ATM models, the lowest TCP decrease was found in C_InH. Increasing the fraction size by C_InH and C_BED provided more TCP improvement than increasing the number of fractions by C_TDF.

CONCLUSION

The treatment gap to be given in the middle of the treatment is more challenging in terms of tumor control. Adaptive approaches that maintain overall treatment time while increasing fractional dose offer increased TCP.

[Practical update of total dose compensation in case of temporary interruption of external radiotherapy in the COVID-19 pandemic context]

L’étalement est un facteur important de récidive locale et indirectement d’évolution à distance, notamment, en cas de durée de traitement allongée. La pandémie actuelle a un impact sur les patients en cours de radiothérapie qui doivent interrompre leur traitement de manière parfois prolongée du fait de la nécessité de soins respiratoires induits par le COVID-19. Les modèles utilisés de compensation de la dose totale en cas d’interruption prolongée de la radiothérapie sont connus, mais il nous a semblé important de synthétiser afin que chaque oncologue radiothérapeute puisse proposer un traitement le plus optimal possible tant en termes de risque de récidive locale que de protection des tissus sains. L’objectif de ce type de recommandation est d’homogénéiser les pratiques de l’ensemble de la discipline.

Pooled Analysis of external-beam RADiotherapy parameters in phase II and phase III trials in radiochemotherapy in Anal Cancer (PARADAC)

PURPOSE

Concomitant external-beam radiochemotherapy (5-fluorouracil-mitomycin C) has become the standard of care in anal cancer since the '90s. A pooled analysis of individual patient data from 7 major trials was performed quantifying the effect of radiation therapy (RT)-related parameters on the outcome of patients with anal cancer.

MATERIALS AND METHODS

Pooling databases from combined modality trials, the impact of RT parameters (total dose, gap duration, OTT: overall treatment time) on outcome including locoregional failure (LRF), 5-year progression free survival (PFS) and toxicities were investigated. Individual patient data were received for 10/13 identified published studies conducted from 1987 to 2008 (n = 3031). A Cox regression model was used (landmark = 3 months after RT for first follow-up).

RESULTS

After data inspection indicating severe heterogeneity between trials, only 1343 patients from 7/10 studies received were analysed (the most recent ones, since 1994; median follow-up = 4.1 years). A higher overall 5-year LRF rate [22.8% (95% confidence interval [CI] 22.3-27.3%)] significantly correlated with longer OTT (p = 0.03), larger tumour size (p < 0.001) and male gender (p = 0.045). Although significant differences were not observed, subset analyses for LRF (dose range: 50.4-59 Gy) seemed to favour lower doses (p = 0.412), and when comparing a 2-week gap versus 3 (dose: 59.4 Gy), results suggested 3 weeks might be detrimental (p = 0.245). For a 2-week gap versus none (dose range: 55-59.4 Gy), no difference was observed (p = 0.89). Five-year PFS was 65.7% (95% CI: 62.8-68.5%). Higher PFS rates were observed in women (p < 0.001), smaller tumour sizes (p < 0.001) and shorter OTT (p = 0.025). Five-year overall survival [76.7% (95% CI: 73.9%-79.3%)] correlated positively with female gender (p < 0.001), small tumour size (p = 0.027) and short OTT (p = 0.026). Descriptive toxicity data are presented.

CONCLUSION

For patients receiving concurrent external-beam doublet chemoradiation, a longer OTT seems detrimental to outcome. Further trials involving modern techniques may better define optimal OTT and total dose.

Management of interruptions in radiotherapy treatments: Adaptive implementation in high workload sites

Owing to predictable or unpredictable causes, interruptions may arise during therapy. On average, the extension of fractionated radiotherapy treatments is prone to be delayed by several weeks and interruptions can come up extending overall treatment time (OTT). Clonogenic cells of aggressive tumors might benefit from this situation, modifying local control (LC). Preserving treatment quality in radiotherapy is an essential issue for the treatment outcome, and our institution is increasingly concerned about this line of work. Establishing some objective criteria to schedule patients that have suffered interruptions along their treatments is of capital importance and not a trivial issue. Publications strongly encourage departments to minimize the effect of lag periods during treatments. Therefore, in July 2017, our facility implemented the so called 'Protocol to Manage Interruptions in Radiotherapy', based on a scoring system for patient categorization that considers not only histology but also associated comorbidity and sequence of the therapy.

Awareness and surveillance of radiation treatment schedules reduces head and neck overall treatment time

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Overall treatment time for HNC treatment was reduced according to DAHANCA guidelines.

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Sufficient accelerator capacity alone did not sufficiently minimize treatment time.

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Surveillance of treatment calendars reduced breaches to 3% (6fx/wk) and 13% (5 fx/wk).

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Radiobiological efficacy was increased by 1.3 Gy (6 fx/wk) and 2.0 Gy (5 fx/wk).

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Surveillance of treatment calendars presented minimal financial costs.

Background and purpose

Overall treatment time (OTT) is essential for local tumour control and survival in radiotherapy of head and neck cancer (HNC). National radiotherapy guidelines of the Danish Head and Neck Cancer Group (DAHANCA) recommend a maximum OTT of 41 days for moderately accelerated radiation treatment (6 fractions/week) and 48 days for conventional treatment (5 fractions/week). The purpose of this study was to evaluate the effect of surveillance of the radiotherapy course length and treatment gaps in HNC patients to reduce OTT.

Methods

The study included 2011 patients with HNC undergoing radical radiation treatment with 66–68 Gy in 33–34 fractions in 2003–2017 at Odense University Hospital. In February 2016, a systematic weekly review by two radiation therapists of all planned treatment courses was introduced to check OTT of individual patients to portend likely breaks or treatment prolongations. Schedules that violated the OTT guidelines were conferred with the responsible radiation oncologist, and treatment rescheduled by treating twice daily to catch up with a delay.

Results

The mean length of accelerated treatment courses was reduced from a maximum of 40.9 days in 2007 to 38.3 days in 2017 and from 50.3 days to 45.9 days for conventional courses. The percentage of individual treatment courses that violated the recommended OTT was reduced to 3% of the accelerated treatments and 13% for the conventional treatments.

Conclusion

Continuous surveillance of treatment schedules of HNC patients by a brief weekly survey reduced treatment course duration to an extent that was radiobiologically and clinically meaningful.

Nutrition and Swallowing Therapy in Head and Neck Cancer: Utilization of Care and Preventative Efficacy

PURPOSE

To examine the impact of ethnicity, Spanish language preference, socioeconomic status, and treatment setting on utilization of supportive services before radiotherapy (RT) among head and neck cancer patients and to determine whether a lack of these services is associated with an increased rate of adverse events.

METHODS AND MATERIALS

Demographic, staging, and treatment details were retrospectively collected for patients treated at a safety-net hospital (n = 56) or adjacent private academic hospital (n = 183) from January 1, 2014, to June 30, 2016. Supportive care services evaluated were limited to speech/swallowing therapy and nutrition therapy. Adverse events and performance measures examined included weight loss during RT, gastric tube placement, emergency department visits, hospital admissions, and missed RT days.

RESULTS

On multivariable analysis, patients receiving treatment at the safety-net hospital were less likely to receive speech/swallowing services. Receiving speech/swallowing therapy before treatment was associated with less weight loss during treatment, and in conjunction with nutrition therapy, was associated with fewer missed RT days.

CONCLUSION

Safety-net hospital treatment was associated with a lack of utilization of pre-RT speech/swallowing therapy which in turn was associated with increased weight loss. Interventions aimed at improving utilization of these services would improve treatment tolerance and patient outcomes.

Barriers affecting adherence to radiation treatment and strategies to overcome those barriers

BACKGROUND

The WHO defines adherence as the extent to which a patient's behavior coincides with recommendations from a health-care provider. Nonadherence to cancer treatment has a major impact on the therapeutic outcome.

AIM OF THE STUDY

To assess the prevalence of nonadherence to radiation regimen and to analyze the factors that affect adherence to cancer treatment.

MATERIALS AND METHODS

Patients receiving radiation treatment in our hospital were screened for adherence to appointment keeping and to the prescribed radiation regimen and patients who had unplanned treatment breaks during treatment were interviewed. Between January and July 2013, we identified 61 patients who had unplanned breaks during treatment. We analyzed the social, emotional, educational, economic, and therapeutic barriers that led to nonadherence.

RESULTS

Of the 61 patients who had unplanned breaks during treatment, 54% were males and 46% were females. Fifty-seven percent of patients had head and neck cancers and 25% had gynecological cancers. Seventy-one percent of patients were planned for concurrent chemoradiation. The number of days of unplanned treatment breaks ranged from 3 to 27 days. Social and therapeutic barriers were found to be the most common factor that led to nonadherence in these patients.

CONCLUSION

Identification of barriers that lead to nonadherence, designing strategies to overcome such barriers and effective communication becomes imperative to ensure uninterrupted treatment. Based on the above analysis, we have designed several strategies to improve adherence to treatment among our patients.

When and how to treat an IMRT patient on a second accelerator without replanning?

When a linear accelerator is unavailable for treatment, a clinical decision is imminent regarding whether a patient should be treated on a linear accelerator other than the machine the patient was scheduled on, or whether treatment should be postponed until the original Linac becomes available. This work investigates the feasibility of switching patients to different accelerators for intensity-modulated radiation therapy (IMRT). We have performed Monte Carlo simulations of photon beams from different Linac models and vendors. Prostate and head and neck (H&N) treatment plans for Siemens Primus, Primart, and Varian 21EX accelerators are studied in this work. Dose distributions for given plans are recalculated using different beam data with the same nominal energy from different Linacs. We have compared dose-volume histograms (DVHs) and the maximum, the minimum, and the mean doses to the target and critical structures because of switching accelerators. In the process of switching a treatment plan to a different accelerator, issues exist, including optimum penumbra compensation, dose distribution at the boundary of target and critical structures, and multileaf collimator (MLC) leaf-width effects, which need to be considered and verified with measurements. Our Monte Carlo simulation results confirm that, for the cases we tested, the dose received by 95% of the planning target volume differs by 0.2% to 1.5% between Siemens Primus and Varian 21EX Linacs. The discrepancy is within our clinical acceptance criteria of 3% for IMRT treatments. In making the final decision on whether to switch machines or not, the tumor control probabilities (TCPs) based on a linear-quadratic model are compared. Based on the analyses performed in this work, it is therapeutically more beneficial to switch a patient to a different machine than to postpone a treatment until the original machine is available, especially for fast-growing tumors such as H&N cancers.

Significant suppression of radiation dermatitis in breast cancer patients using a topically applied adrenergic vasoconstrictor

Background

Our previous studies showed that vasoconstrictor applied topically to rat skin minutes before irradiation completely prevented radiodermatitis. Here we report on a Phase IIa study of topically applied NG12-1 vasoconstrictor to prevent radiodermatitis in post-lumpectomy breast cancer patients who received at least 40 Gray to the whole breast using standard regimens.

Methods

Patients had undergone surgery for Stage Ia, Ib, or IIa infiltrating ductal or lobular carcinoma of the breast or ductal carcinoma in situ. NG12-1 formulation was applied topically to the same 50-cm² treatment site within the radiation field 20 min before each daily radiotherapy fraction.

Results

Scores indicated significant reductions in radiodermatitis at the NG12-1 treatment site versus control areas in the same radiotherapy field. The mean dermatitis score for all subjects was 0.47 (SD 0.24) in the NG12-1-treated area versus 0.72 (SD 0.22) in the control area (P = 0.022). Analysis by two independent investigators indicated radiodermatitis reductions in 9 of the 9 patients with scorable radiodermatitis severity, and one patient with insufficient radiodermatitis to enable scoring. There were no serious adverse events from NG12-1 treatment.

Conclusions

Thirty, daily, NG12-1 treatments, topically applied minutes before radiotherapy, were well tolerated and conferred statistically significant reductions in radiodermatitis severity (P = 0.022).

Trial registration

NCT01263366; clinicaltrials.gov

The "rocky treatment course": identifying a high-risk subgroup of head and neck cancer patients for supportive interventions

PURPOSE

We aim to identify the risk factors for a "rocky" treatment course (RTC) in head and neck cancer.

METHODS

A retrospective case-control study was conducted utilizing data from a prospective study. We defined the RTC as a composite of adverse outcomes including G-tube dependence and increased nursing interventions. Statistically associative variables were included in a multivariable logistic regression. We also evaluated whether the RTC, or its components, associated with worse cancer outcomes.

RESULTS

Being single, unemployed, having N2/3 disease and receiving chemoradiotherapy were associated with a RTC. In turn, G-tube dependence was associated with worse 3-year OS (73 vs 91 %; p = 0.02) and increased nursing interventions with worse 3-year locoregional recurrence-free survival (LRFS) (85 vs 92 %; p = 0.03) and locoregional recurrence (LRR) (14 vs 7 %; p = 0.03).

CONCLUSIONS

We identified baseline factors associated with a RTC for head and neck cancer patients. Future supportive care interventions could be evaluated using the RTC as a marker of benefit.

Complete prevention of radiation-induced dermatitis using topical adrenergic vasoconstrictors

Radiation dermatitis is a commonly occurring, painful, side effect of cancer radiotherapy that causes some patients to withdraw from the radiotherapy course. Our goal was to test and optimize topical application of an adrenergic vasoconstrictor to rat skin in a preclinical test to prevent radiation-induced dermatitis. A radiation dermatitis assay was developed in which 17.2 Gy to a 1.5 × 3.0 cm rectangle on the clipped dorsal back of rats yielded Grade 3 radiation dermatitis over the irradiated area 13 days later. Single, topical applications of each of three adrenergic vasoconstrictors, epinephrine, norepinephrine, or phenylephrine, in various vehicle formulations, doses, and application schedules, were tested to determine their efficacy in preventing radiation dermatitis. Each of the three adrenergic agonists conferred 100 % prevention of radiation dermatitis in linear, dose-dependent manners and their EC₅₀ potencies in preventing radiation dermatitis correlated well with their individual K _d association constants for binding to mammalian α-adrenergic receptors. Topical vasoconstrictor application as little as 3-12 min before irradiation gave 80-100 % prevention, respectively, of radiation dermatitis. There was a strong correlation between the extent (0-100 %) of skin blanch present in skin immediately before irradiation and prevention of radiation dermatitis scored 13 days after irradiation. The data presented here demonstrate that topical application of adrenergic vasoconstrictors to rat skin before a large, 17.2 Gy, radiation insult confers 100 % protection against radiation dermatitis and support ongoing clinical trials and commercial development of a vasoconstrictor-based product to prevent radiotherapy-induced dermatitis.

What is changing in radiotherapy for the treatment of locally advanced nonsmall cell lung cancer patients? A review

Radiotherapy treatment continues to have a relevant impact in the treatment of nonsmall cell cancer (NSCLC). Use of concurrent chemotherapy and radiotherapy is considered the gold standard in the treatment of locally advanced NSCLC but clinical outcomes are not satisfactory. Introduction of new radiotherapy technology and chemotherapy regimens are under investigation in this setting with the goal to improve unsatisfactory results. We report how radiotherapy is changing in the treatment of locally advanced NSCLC.

[Overall treatment time assessment of radiotherapy delivered in a curative intent: A prospective study]

PURPOSE

To assess the overall treatment time of radiotherapy delivered with curative intent in a cohort of 185 consecutive patients and the causes of this possible delay. If delay, to propose corrective actions.

MATERIALS AND METHODS

We report a single-center prospective study including all consecutive patients receiving a radiation therapy with curative intent, from 1st December 2013 to 28th February 2014, on the three linear accelerators of the radiotherapy department. For each fraction missed, the causes of non-completion were prospectively collected. This analysis took into account the following parameters: age, sex, occupation, transport type and duration, tumour localization, radiation dose, concomitant chemotherapy, hospitalization, type of linear accelerator.

RESULTS

One hundred and fifty-five patients were included in the study (183 evaluable, two did not complete treatment). The overall treatment time was respected for 31 patients (17%). It was lengthened on 4.6 days (d) (0-29 d; median: 3d). The mean number of delayed fractions was 3.4 (0-17; median: 2). The reasons of delay were: breakdown 32.2%; maintenance 29.3%; holiday 11%; treatment toxicity 9.4%; inadequate planning 8.6%; other disease 3.9%; treatment refusal 2.1%; unspecified personal reasons 1.5%; refusal to wait 0.8%; transportation 0.3%; error of communication 0.3%; other 0.6%. Two parameters had a significant impact on the overall treatment time: the type of linear accelerator in relation to breakdown occurrence (P<0.001) and transportation duration (more or less than 40 min, P=0.022). One hundred and thirty-eight patients (75%) and 79 patients (43%) were treated on one or more than two Saturdays. Treatment on Saturday significantly reduced the overall treatment time (median, 1.9 d; P<0.001).

CONCLUSION

The overall treatment time was globally respected excluding break down and maintenance. Their impact on the overall treatment time is minimized by the systematic opening of the department on Saturdays.

Effect of radiotherapy delay in overall treatment time on local control and survival in head and neck cancer: Review of the literature

Treatment delays in completing radiotherapy (RT) for many neoplasms are a major problem affecting treatment outcome, as increasingly shown in the literature. Overall treatment time (OTT) could be a critical predictor of local tumor control and/or survival. In an attempt to establish a protocol for managing delays during RT, especially for heavily overloaded units, we have extensively reviewed the available literature on head and neck cancer. We confirmed a large deleterious effect of prolonged OTT on both local control and survival of these patients.

Accelerated repopulation as a cause of radiation treatment failure in non-small cell lung cancer: review of current data and future clinical strategies

Despite convincing evidence that the principles of accelerated repopulation would open up additional therapeutic opportunities in the treatment of advanced-stage non-small cell lung cancer, this strategy has been generally underexplored. The implementation of accelerated radiotherapy schedules has been hampered by logistical barriers, concerns about acute toxicity, and the prioritization of integrating concurrent chemotherapy into the standard treatment platform. At present, it is unclear to what extent accelerated fractionation will influence future treatment paradigms in non-small cell lung cancer, although technical advances in radiotherapy, allowing higher dose delivery with reduced toxicity, could permit the development of more convenient and tolerable forms of accelerated schedules.

A matter of timing: identifying significant multi-dose radiotherapy improvements by numerical simulation and genetic algorithm search

Multi-dose radiotherapy protocols (fraction dose and timing) currently used in the clinic are the product of human selection based on habit, received wisdom, physician experience and intra-day patient timetabling. However, due to combinatorial considerations, the potential treatment protocol space for a given total dose or treatment length is enormous, even for relatively coarse search; well beyond the capacity of traditional in-vitro methods. In constrast, high fidelity numerical simulation of tumor development is well suited to the challenge. Building on our previous single-dose numerical simulation model of EMT6/Ro spheroids, a multi-dose irradiation response module is added and calibrated to the effective dose arising from 18 independent multi-dose treatment programs available in the experimental literature. With the developed model a constrained, non-linear, search for better performing cadidate protocols is conducted within the vicinity of two benchmarks by genetic algorithm (GA) techniques. After evaluating less than 0.01% of the potential benchmark protocol space, candidate protocols were identified by the GA which conferred an average of 9.4% (max benefit 16.5%) and 7.1% (13.3%) improvement (reduction) on tumour cell count compared to the two benchmarks, respectively. Noticing that a convergent phenomenon of the top performing protocols was their temporal synchronicity, a further series of numerical experiments was conducted with periodic time-gap protocols (10 h to 23 h), leading to the discovery that the performance of the GA search candidates could be replicated by 17-18 h periodic candidates. Further dynamic irradiation-response cell-phase analysis revealed that such periodicity cohered with latent EMT6/Ro cell-phase temporal patterning. Taken together, this study provides powerful evidence towards the hypothesis that even simple inter-fraction timing variations for a given fractional dose program may present a facile, and highly cost-effecitive means of significantly improving clinical efficacy.

Competing causes of death and medical comorbidities among patients with human papillomavirus-positive vs human papillomavirus-negative oropharyngeal carcinoma and impact on adherence to radiotherapy

IMPORTANCE

Survival of patients with head and neck cancer can be affected by competing causes of mortality, as well as comorbidities that result in radiation treatment interruptions.

OBJECTIVE

To discern how differences in preexisting medical and psychosocial comorbidities potentially influence adherence to radiation therapy according to human papillomavirus (HPV) status.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective analysis at a comprehensive cancer center of 162 consecutive patients with locally advanced squamous cell carcinoma of the oropharynx treated with primary chemoradiation (n = 95) or primary surgery followed by adjuvant radiation (n = 67). Immunostaining for p16 was used to determine HPV status.

MAIN OUTCOMES AND MEASURES

Difference in alcohol, tobacco, and marijuana use was compared between patients with HPV-positive and HPV-negative tumors, as well as the prevalence of the following comorbidities: diabetes mellitus, chronic obstructive pulmonary disease (COPD), anxiety disorder, and major depression. The number of total missed treatment days was analyzed as both a continuous and categorical variable.

RESULTS

Rates of self-reported heavy alcohol use (47% vs 16%; P = .02) and any marijuana use (47% vs 23%; P = .003) were significantly higher among HPV-negative patients. Fifty-four percent of HPV-positive patients self-identified as never smokers, compared with only 12% of HPV-negative patients (P < .001). HPV-negative patients had more missed treatment days (mean, 2.8 vs 1.7 days; P = .02), as well as an increased rate of at least 5 missed days (24% vs 10%; P = .04), and higher prevalences of COPD (12% vs 7%; P = .37) and anxiety disorder (12% vs 6%; P = .35).

CONCLUSIONS AND RELEVANCE

Pronounced differences exist in lifestyle habits between patients with HPV-negative and HPV-positive oropharyngeal cancer at diagnosis. These differences, as well as those of medical and psychosocial burden, may contribute to observed discrepancies in treatment adherence and need to be considered in outcomes reporting and clinical trial design.

Modern post-operative radiotherapy for stage III non-small cell lung cancer may improve local control and survival: a meta-analysis

BACKGROUND

We hypothesized that modern postoperative radiotherapy (PORT) could decrease local recurrence (LR) and improve overall survival (OS) in patients with stage IIIA-N2 non-small-cell lung cancer (NSCLC).

METHODS

To investigate the effect of modern PORT on LR and OS, we identified published phase III trials for PORT and stratified them according to use or non-use of linear accelerators. Non-individual patient data were used to model the potential benefit of modern PORT in stage IIIA-N2 NSCLC treated with induction chemotherapy and resection.

RESULTS

Of the PORT phase III studies, eleven trials (2387 patients) were included for OS analysis and eight (1677 patients) for LR. PORT decreased LR, whether given with cobalt, cobalt and linear accelerators, or with linear accelerators only. An increase in OS was only seen when PORT was given with linear accelerators, along with the most significant effect on LR (relative risk for LR and OS 0.31 (p=0.01) and 0.76 (p=0.02) for PORT vs. controls, respectively). Four trials (357 patients) were suitable to assess LR rates in stage III NSCLC treated with surgery, in most cases after induction chemotherapy. LR as first relapse was 30% (105/357) after 5 years. In the modeling part, PORT with linear accelerators was estimated to reduce LR rates to 10% as first relapse and to increase the absolute 5-year OS by 13%.

CONCLUSIONS

This modeling study generates the hypothesis that modern PORT may increase both LR and OS in stage IIIA-N2 NSCLC even in patients being treated with induction chemotherapy and surgery.

Modelling the interplay between hypoxia and proliferation in radiotherapy tumour response

A tumour control probability computational model for fractionated radiotherapy was developed, with the goal of incorporating the fundamental interplay between hypoxia and proliferation, including reoxygenation over a course of radiotherapy. The fundamental idea is that the local delivery of oxygen and glucose limits the amount of proliferation and metabolically-supported cell survival a tumour sub-volume can support. The model has three compartments: a proliferating compartment of cells receiving oxygen and glucose; an intermediate, metabolically-active compartment receiving glucose; and a highly hypoxic compartment of starving cells. Following the post-mitotic cell death of proliferating cells, intermediate cells move into the proliferative compartment and hypoxic cells move into the intermediate compartment. A key advantage of the proposed model is that the initial compartmental cell distribution is uniquely determined from the assumed local growth fraction (GF) and volume doubling time (TD) values. Varying initial cell state distributions, based on the local (voxel) GF and TD, were simulated. Tumour response was simulated for head and neck squamous cell carcinoma using relevant parameter values based on published sources. The tumour dose required to achieve a 50% local control rate (TCD50) was found for various GFs and TD's, and the effect of fraction size on TCD50 was also evaluated. Due to the advantage of reoxygenation over a course of radiotherapy, conventional fraction sizes (2-2.4 Gy fx(-1)) were predicted to result in smaller TCD50's than larger fraction sizes (4-5 Gy fx(-1)) for a 10 cc tumour with GFs of around 0.15. The time to eliminate hypoxic cells (the reoxygenation time) was estimated for a given GF and decreased as GF increased. The extra dose required to overcome accelerated stem cell accumulation in longer treatment schedules was estimated to be 0.68 Gy/day (in EQD26.6), similar to published values derived from clinical data. The model predicts, for a 2 Gy/weekday fractionation, that increased initial proliferation (high GF) should, surprisingly, lead to moderately higher local control values. Tumour hypoxia is predicted to increase the required dose for local control by approximately 30%. Predicted tumour regression patterns are consistent with clinical observations. This simple yet flexible model shows how the local competition for chemical resources might impact local control rates under varying fractionation conditions.

Modelling the correlation between EGFr expression and tumour cell radiosensitivity, and combined treatments of radiation and monoclonal antibody EGFr inhibitors

Purpose

To estimate the effects of heterogeneity on tumour cell sensitivity to radiotherapy combined with radiosensitizing agents attributable to differences in expression levels of Epidermal Growth Factor Receptor (EGFr).

Materials and methods

Differences in radiosensitivity are not limited to cells of different cancer histotypes but also occur within the same cancer, or appear during radiotherapy if radiosensitizing drugs are combined with ionizing radiation. A modified biologically effective dose (MBED), has been introduced to account for changes in radiosensitivity parameters (α and α/β) rather than changes in dose/fraction or total dose as normally done with standard biologically effective dose (BED). The MBED approach was applied to cases of EGFr over-expression and cases where EGFr inhibitors were combined with radiation. Representative examples in clinical practice were considered.

Results

Assuming membrane EGFr over-expression corresponds to reduced radiosensitivity (α_H = 0.15 Gy^-1 and α_H/β_H = 7.5 Gy) relative to normal radiosensitivity (α = 0.2 Gy^-1 and α/β = 10 Gy), an increased dose per fraction of 2.42 Gy was obtained through the application of MBED, which is equivalent to the effect of a reference schedule with 30 fractions of 2 Gy. An equivalent hypo-fractionated regime with a dose per fraction of 2.80 Gy is obtained if 25 fractions are set. Dose fractionations modulated according to drug pharmacokinetics are estimated for combined treatments with biological drugs. Soft and strong modulated equivalent hypo-fractionations result from subtraction of 5 or 10 fractions, respectively.

Conclusions

During this computational study, a new radiobiological tool has been introduced. The MBED allows the required dose per fraction to be estimated when tumour radiosensitivity is reduced because EGFr is over-expressed. If radiotherapy treatment is combined with EGFr inhibitors, MBED suggests new treatment strategies, with schedules modulated according to drug pharmacokinetics.

ROS-scavenger and radioprotective efficacy of the new PrC-210 aminothiol

To identify new aminothiol radioprotectors that are active when applied topically and have fewer side effects when administered systemically, a new family of aminothiol radioprotectors was designed and synthesized. Three key elements in the aminothiol design were, (1) small size for efficient transmembrane diffusion, (2) positive charged amines in alkyl backbone for strong ionic interaction with DNA backbone, and (3) a perpendicular, alkyl side-chain with a terminal thiol that is projected away from the DNA backbone to enable reactive oxygen species scavenging around DNA. Several in vitro assays were used to characterize the prototype aminothiol, PrC-210, for efficacy: protection against reactive oxygen species-induced plasmid DNA nicking, mass spectrometry to detect aminothiol-reactive oxygen species by-products, S. typhimurium mutagenesis, human cell growth inhibition, Western blot for p21 expression, and FACS analysis. Additionally, two in vivo assays were used to assess radioprotective efficacy; a Sprague-Dawley rat dorsal skin radiodermatitis assay was developed to screen for aminothiol efficacy when topically applied, and ICR mouse survival was scored after systemic PrC-210 administration and whole-body radiation. PrC-210 efficiently scavenged reactive oxygen species and completely protected supercoiled plasmid DNA against reactive oxygen species-induced damage. Neither PrC-210 nor its analog PrC-211 were bacterial mutagens. In cell culture, PrC-210 application to diploid human fibroblasts showed: (1) inhibition of cell growth with an IC(70) of 4.1 mM, (2) induced levels of p21 expression, and (3) a G(1)/S-cell cycle block that was reversed after washout of PrC-210-containing medium. In rodents, PrC-210 was an effective radioprotector showing: (1) complete prevention of Grade 2-3 radiodermatitis when applied topically (370 mM in ethanol:propylene glycol:water solution) prior to skin irradiation, (2) complete prevention of Grade 2-3 radiodermatitis when administered by i.p. injection (200 μg/g of body weight) before skin irradiation, (3) 100% survival of mice from an otherwise 100% lethal dose of whole-body radiation (8.75 Gy) when administered by i.p. injection (252 μg/g of body weight = 0.5 × maximum tolerated dose) before irradiation, and (4) a dose reduction factor of 1.6, the same as amifostine. These data suggest that the PrC-210 aminothiol is a plausible candidate for drug development as a human pre-exposure radioprotector.

Stereotactic body radiation therapy in non-small-cell lung cancer: linking radiobiological modeling and clinical outcome

For patients with peripheral, early-stage non-small-cell lung cancer, it has been found feasible to deliver 5 or fewer fractions of large doses through stereotactic body radiation therapy (SBRT) without causing severe early or late injury and with impressive tumor control. In this review, we employ radiobiological modeling with the linear quadratic formulation to explore the adequacy of various dose schedules used for tumor control in the lung as supported by clinical evidence, the influence of dose distribution and delivery time on local control, and how to decrease the likelihood of severe toxicity following SBRT. Furthermore, the validity of the linear quadratic formalism in the high dose range of SBRT for lung cancer is explored.

"Mind the gap"--the impact of variations in the duration of the treatment gap and overall treatment time in the first UK Anal Cancer Trial (ACT I)

PURPOSE

The United Kingdom Coordinating Committee on Cancer Research anal cancer trial demonstrated the benefit of combined modality treatment (CMT) using radiotherapy (RT), infusional 5-fluorouracil, and mitomycin C over RT alone. The present study retrospectively examines the impact of the recommended 6-week treatment gap and local RT boost on long-term outcome.

METHODS AND MATERIALS

A total of 577 patients were randomly assigned RT alone or CMT. After a 6-week gap responders received a boost using either additional external beam radiotherapy (EBRT) (15 Gy) or iridium-192 implant (25 Gy). The effect of boost, the gap between initial treatment (RT alone or CMT) and boost (Tgap), and overall treatment time (OTT) were examined for their impact on outcome.

RESULTS

Among the 490 good responders, 436 (89%) patients received a boost after initial treatment. For boosted patients, the risk of anal cancer death decreased by 38% (hazard ratio [HR]: 0.62, 99% CI 0.35-1.12; p=0.04), but there was no evidence this was mediated via a reduction in locoregional failure (LRF) (HR: 0.90, 99% CI 0.48-1.68; p=0.66). The difference in Tgap was only 1.4 days longer for EBRT boost, compared with implant (p=0.51). OTT was longer by 6.1 days for EBRT (p=0.006). Tgap and OTT were not associated with LRF. Radionecrosis was reported in 8% of boosted, compared with 0% in unboosted patients (p=0.03).

CONCLUSIONS

These results question the benefit of a radiotherapy boost after a 6-week gap. The higher doses of a boost may contribute more to an increased risk of late morbidity, rather than local control.

21 years of biologically effective dose

In 1989 the British Journal of Radiology published a review proposing the term biologically effective dose (BED), based on linear quadratic cell survival in radiobiology. It aimed to indicate quantitatively the biological effect of any radiotherapy treatment, taking account of changes in dose-per-fraction or dose rate, total dose and (the new factor) overall time. How has it done so far? Acceptable clinical results have been generally reported using BED, and it is in increasing use, although sometimes mistaken for "biologically equivalent dose", from which it differs by large factors, as explained here. The continuously bending nature of the linear quadratic curve has been questioned but BED has worked well for comparing treatments in many modalities, including some with large fractions. Two important improvements occurred in the BED formula. First, in 1999, high linear energy transfer (LET) radiation was included; second, in 2003, when time parameters for acute mucosal tolerance were proposed, optimum overall times could then be "triangulated" to optimise tumour BED and cell kill. This occurs only when both early and late BEDs meet their full constraints simultaneously. New methods of dose delivery (intensity modulated radiation therapy, stereotactic body radiation therapy, protons, tomotherapy, rapid arc and cyberknife) use a few large fractions and obviously oppose well-known fractionation schedules. Careful biological modelling is required to balance the differing trends of fraction size and local dose gradient, as explained in the discussion "How Fractionation Really Works". BED is now used for dose escalation studies, radiochemotherapy, brachytherapy, high-LET particle beams, radionuclide-targeted therapy, and for quantifying any treatments using ionising radiation.

Dose escalation for metastatic spinal cord compression in patients with relatively radioresistant tumors

PURPOSE

Radiotherapy alone is the most common treatment for metastatic spinal cord compression (MSCC) from relatively radioresistant tumors such as renal cell carcinoma, colorectal cancer, and malignant melanoma. However, the results of the "standard" regimen 30 Gy/10 fractions need to be improved with respect to functional outcome. This study investigated whether a dose escalation beyond 30 Gy can improve treatment outcomes.

METHODS AND MATERIALS

A total of 91 patients receiving 30 Gy/10 fractions were retrospectively compared to 115 patients receiving higher doses (37.5 Gy/15 fractions, 40 Gy/20 fractions) for motor function and local control of MSCC. Ten further potential prognostic factors were evaluated: age, gender, tumor type, performance status, number of involved vertebrae, visceral or other bone metastases, interval from tumor diagnosis to radiotherapy, pretreatment ambulatory status, and time developing motor deficits before radiotherapy.

RESULTS

Motor function improved in 18% of patients after 30 Gy and in 22% after higher doses (p = 0.81). On multivariate analysis, functional outcome was associated with visceral metastases (p = 0.030), interval from tumor diagnosis to radiotherapy (p = 0.010), and time developing motor deficits (p < 0.001). The 1-year local control rates were 76% after 30 Gy and 80% after higher doses, respectively (p = 0.64). On multivariate analysis, local control was significantly associated with visceral metastases (p = 0.029) and number of involved vertebrae (p = 0.043).

CONCLUSIONS

Given the limitations of a retrospective study, escalation of the radiation dose beyond 30 Gy/10 fractions did not significantly improve motor function and local control of MSCC in patients with relatively radioresistant tumors.

Systemic review of the patterns of failure following stereotactic body radiation therapy in early-stage non-small-cell lung cancer: clinical implications

PURPOSE

To analyze the patterns of failure, the toxicity profile, and the factors influencing efficacy of stereotactic body radiation (SBRT) for early-stage non-small-cell lung cancer (NSCLC).

METHODS AND MATERIALS

A search was based on PubMed electronic databases. All searches were conducted in May, 2009.

RESULTS

The local control ranged from 80% to 100% in most studies with adequate isocentric or peripheral biologically effective dose (BED). Recurrences were associated with increased tumor size. The main pattern of failure after SBRT was distant metastasis. Grades 3-5 toxicity occurred mostly in centrally located tumors, and adjuvant chemotherapy may further decrease all recurrences; possibly translating to a survival benefit in large or centrally located tumors where high BED cannot be safely reached.

CONCLUSION

SBRT is an excellent treatment option for early-stage, and mostly medically inoperable, NSCLC. BED at both the isocenter and the tumor periphery is very important for optimal tumor control; higher doses are required for large (T2) lesions; SBRT for centrally located tumors can be feasible with a much less aggressive dose regimen than 60-66Gy/3 fractions and adjacent critical structures excluded from the target volume; chemotherapy may optimize the clinical outcome in large or centrally located lesions.

A mathematical model for brain tumor response to radiation therapy

Gliomas are highly invasive primary brain tumors, accounting for nearly 50% of all brain tumors (Alvord and Shaw in The pathology of the aging human nervous system. Lea & Febiger, Philadelphia, pp 210-281, 1991). Their aggressive growth leads to short life expectancies, as well as a fairly algorithmic approach to treatment: diagnostic magnetic resonance image (MRI) followed by biopsy or surgical resection with accompanying second MRI, external beam radiation therapy concurrent with and followed by chemotherapy, with MRIs conducted at various times during treatment as prescribed by the physician. Swanson et al. (Harpold et al. in J Neuropathol Exp Neurol 66:1-9, 2007) have shown that the defining and essential characteristics of gliomas in terms of net rates of proliferation (rho) and invasion (D) can be determined from serial MRIs of individual patients. We present an extension to Swanson's reaction-diffusion model to include the effects of radiation therapy using the classic linear-quadratic radiobiological model (Hall in Radiobiology for the radiologist. Lippincott, Philadelphia, pp 478-480, 1994) for radiation efficacy, along with an investigation of response to various therapy schedules and dose distributions on a virtual tumor (Swanson et al. in AACR annual meeting, Los Angeles, 2007).

Causas de interrupção não-programadas da radioterapia

OBJETIVO: Avaliar a ocorrência e as causas de interrupção não-programadas da radioterapia. MATERIAIS E MÉTODOS: Estudo retrospectivo realizado no Serviço de Radioterapia do Hospital Alemão Oswaldo Cruz, na cidade de São Paulo, SP. Os dados foram obtidos dos prontuários dos 560 pacientes submetidos a radioterapia, de 1º de janeiro de 2005 a 31 de dezembro de 2005. Os dados foram analisados pelos testes qui-quadrado e t Student, e os valores de p < 0,05 foram considerados com significância estatística. RESULTADOS: Foram identificados 350 pacientes que interromperam seus tratamentos, o que representou 62,5% do total da amostra. Os motivos foram: manutenção do aparelho (55%), motivos particulares dos pacientes (13%), reações do tratamento ou da associação com quimioterapia (6%), piora clínica (3%), associação de motivos (23%). O intervalo de tempo de interrupção variou de 1 a 24 dias, com média geral de 1,4 dia. Na interrupção de um dia a maior incidência foi ocasionada pela manutenção (84,4%); de dois a cinco dias a interrupção foi causada pela associação de motivos (48,28%). CONCLUSÃO: A causa mais freqüente de interrupção encontrada foi a manutenção preventiva e seu intervalo máximo foi de dois dias.

Gap compensation during accelerated hypofractionated radiotherapy in head and neck cancer

Introduction:In squamous-cell carcinoma (SCC) of the head and neck, unplanned gaps risk prolongation of the overall treatment time (OTT) and reduction in tumour control. This audit determines whether further acceleration can safely be employed to compensate for missed treatments during accelerated hypofractionated radiotherapy.

Methods:Patients receiving accelerated hypofractionated radiotherapy for SCC of the head and neck were prospectively audited. Outcome measures were OTT, degree of compensation and acute toxicity determined by incidence of grade 3 mucositis, prolonged grade 3 mucositis, grade 3 dysphagia and pain.

Results:In the 87 patients identified, the dose administered was 55 Gy in 20 fractions (81 patients), 50 Gy in 20 fractions (1 patient) and 50 Gy in 16 fractions (5 patients). Of those patients receiving 20 fractions, 94% completed within 28 days. Grade 3 mucositis was seen in 56 patients (64%). Compensating for unplanned gaps did not result in any significant increase in toxicity. Administering 6 fractions/week, as compensation, was associated with a lower pain score (p= 0.003) as was receiving 2 fractions on the same day (p= 0.0004).

Conclusions:Accelerated hypofractionation is tolerable with most patients completing treatment within the planned OTT. When unplanned gaps occur, then compensation by further acceleration is possible.