Dose fractionation and regeneration in radiotherapy for cancer of the oral cavity and oropharynx: tumor dose-response and repopulation

Higher Rates of Inadequate Adjuvant Radiation Dose Among Older Adults with Head and Neck Cancer

OBJECTIVE

To determine the rate of inadequate radiotherapy and identify risk factors associated with inadequate adjuvant radiotherapy for head and neck cancer among older adults.

METHODS

A retrospective review of the National Cancer Database (NCDB) was performed to identify patients diagnosed with squamous cell cancer of the head and neck between 2004 and 2017. Patients with a single malignancy, negative surgical margins, no extranodal extension, and receipt of adjuvant radiation without systemic therapy were included in the study cohort. The main outcome of interest was the adjuvant radiation dose received. Participant data were compared using univariable, multivariable, and correlation analyses to evaluate risk factors for inadequate radiation therapy (RT) dosing.

RESULTS

Among 7608 patients, 1010 patients (13.3%) received an inadequate radiation dose and 6598 (86.7%) received an adequate dose. Patients living in a higher income zip-code, younger age, and those who received intensity-modulated RT (IMRT) were more likely to receive an adequate radiation dose (p < 0.05). Patients older than 70 and 80 years old had a greater likelihood of receiving an inadequate radiation dose (≥70 vs. <70: 16.9% vs. 12.5%; p < 0.05 and ≥80 vs. <80: 20.6% vs. 13.0%%; p < 0.05). Similarly, increasing age was negatively correlated with radiation dose (correlation coefficient: -0.05; p < 0.001).

CONCLUSION

A substantial proportion of older patients receiving adjuvant radiation do not complete the full treatment. Older age, year of diagnosis, non-IMRT, and living in a lower-income zip code were associated with early termination of RT. Future studies should examine strategies to improve tolerance of adjuvant RT so that more patients complete the full treatment.

LEVEL OF EVIDENCE

3; Cohort Study Laryngoscope, 134:2206-2211, 2024.

Platinum-based adjuvant chemoradiotherapy versus adjuvant radiotherapy in patients with head and neck adenoid cystic carcinoma

PURPOSE

The objective of the study was to assess the effectiveness and toxicity of platinum-based adjuvant chemoradiotherapy (POCRT) in comparison to postoperative radiotherapy (PORT) in patients with head and neck adenoid cystic carcinoma (HNACC).

MATERIALS AND METHODS

This retrospective study analyzed patients diagnosed with HNACC at our center between January 2010 and April 2020. A 1:1 propensity score matching method was used to create a matched cohort.

RESULTS

In this study, 206 patients were analyzed, with 147 patients (71.4%) receiving postoperative radiotherapy (PORT) and 59 patients (28.6%) receiving POCRT. Twenty-one patients experienced local-regional failure. The 3-, 5-, and 10-yr local-regional control (LRC) rate for the cohort were 92.0%, 90.6%, and 86.9%, respectively. In both the entire cohort and the matched cohort, the POCRT group exhibited superior LRC compared to the PORT group (Gray's test, all P < 0.05*). Multivariate analysis identified adjuvant concurrent chemotherapy as an independent prognostic factor for LRC (Competing risks regression, HR = 0.144, 95% CI 0.026-0.802, P = 0.027*). In addition, the POCRT group had higher incidences of upper gastrointestinal toxicity and hematologic toxicities, including leukopenia, neutropenia, and anemia (all P < 0.05*).

CONCLUSION

In terms of reducing locoregional failures in HNACC patients, POCRT may potentially offer a more effective therapeutic approach than using PORT alone, although it also entails an augmented burden of treatment-related toxicity.

Optimal Radiation Therapy Fractionation Regimens for Early-Stage Non-Small Cell Lung Cancer

PURPOSE

A series of radiobiological models were developed to study tumor control probability (TCP) for stereotactic body radiation therapy (SBRT) of early-stage non-small cell lung cancer (NSCLC) per the Hypofractionated Treatment Effects in the Clinic (HyTEC) working group. This study was conducted to further validate 3 representative models with the recent clinical TCP data ranging from conventional radiation therapy to SBRT of early-stage NSCLC and to determine systematic optimal fractionation regimens in 1 to 30 fractions for radiation therapy of early-stage NSCLC that were found to be model-independent.

METHODS AND MATERIALS

Recent clinical 1-, 2-, 3-, and 5-year actuarial or Kaplan-Meier TCP data of 9808 patients from 56 published papers were collected for radiation therapy of 2 to 4 Gy per fraction and SBRT of early-stage NSCLC. This data set nearly triples the original HyTEC sample, which was used to further validate the HyTEC model parameters determined from a fit to the clinical TCP data.

RESULTS

TCP data from the expanded data set are well described by the HyTEC models with α/β ratios of about 20 Gy. TCP increases sharply with biologically effective dose and reaches an asymptotic maximal plateau, which allows us to determine optimal fractionation schemes for radiation therapy of early-stage NSCLC.

CONCLUSIONS

The HyTEC radiobiological models with α/β ratios of about 20 Gy determined from the fits to the clinical TCP data for SBRT of early-stage NSCLC describe the recent TCP data well for both radiation therapy of 2 to 4 Gy per fraction and SBRT dose and fractionation schemes of early-stage NSCLC. A steep dose response exists between TCP and biologically effective dose, and TCP reaches an asymptotic maximum. This feature results in model-independent optimal fractionation regimens determined whenever safe for SBRT and hypofractionated radiation therapy of early-stage NSCLC in 1 to 30 fractions to achieve asymptotic maximal tumor control, and T2 tumors require slightly higher optimal doses than T1 tumors. The proposed optimal fractionation schemes are consistent with clinical practice for SBRT of early-stage NSCLC.

Importance of tumor volume, overall treatment time and fractionation sensitivity for p16-positive and p16-negative oropharyngeal tumors

BACKGROUND

Analyses of clinical outcomes following radiotherapy (RT) have advanced our understanding of fundamental radiobiological characteristics in head and neck squamous cell carcinoma (HNSCC). Low fractionation sensitivity appears to be a common feature, as well as susceptibility to changes in overall treatment time (OTT). Large tumors should be harder to cure if a successful RT requires the sterilization of all clonogenic cells. Congruently, primary tumor volume has proven to be an important parameter. However, most findings come from an era when p16-negative HNSCC was the dominant tumor type. HPV-associated, p16-positive, oropharyngeal tumors (OPSCC) are more radiosensitive and have better outcome. The current study aims to investigate the role of primary tumor volume, OTT and estimate α/ β -ratio for p16-positive OPSCC, and to quantify the differences in radiosensitivity depending on p16-status.

METHODS

A cohort of 523 patients treated with RT was studied using a tumor control probability (TCP)-model that incorporates primary tumor volume (V) raised to an exponent c, OTT and α/ β -estimation. The significance of V was also investigated in Cox-regression models.

RESULTS

In the p16-positive cohort (n = 433), the volume exponent c was 1.44 (95%CI 1.06-1.91), compared to 0.90 (0.54-1.32) for p16-negative tumors (n = 90). Hazard ratios per tumor volume doubling were 2.37 (1.72-3.28) and 1.83 (1.28-2.62) for p16-positive and p16-negative, respectively. The estimated α/ β -ratio was 9.7 Gy (-2.3-21.6), and a non-significant daily loss of 0.30 Gy (-0.17-0.92) was found. An additional dose of 6.8 Gy (interquartile range 4.8-9.1) may theoretically counteract the more radioresistant behavior of p16-negative tumors.

CONCLUSION

Primary tumor volume plays a crucial role in predicting local tumor response, particularly in p16-positive OPSCC. The estimated α/β-ratio for p16-positive oropharyngeal tumors aligns with previous HNSCC studies, whereas the impact of prolonged OTT was slightly less than previously reported. The differences in radiosensitivity depending on p16-status were quantified. The findings should be validated in independent cohorts.

Electron paramagnetic resonance dose measurements in teeth of tissue donors to the United States Transuranium and Uranium Registries

The United States Transuranium and Uranium Registries (USTUR) is a research program that studies actinide biokinetics in occupationally exposed individuals with known intakes of these elements. Electron paramagnetic resonance (EPR) in tooth enamel was applied to reconstruct external doses of nine USTUR registrants. Only in two cases there is a reasonable agreement between the EPR-measured dose and the worksite external dose record. For two registrants, high EPR doses can be explained by possible cancer radiotherapy. For the remaining five cases, EPR doses significantly exceed official occupational doses with no plausible explanation for the observed discrepancy. More EPR dose measurements need to be done to explain this anomaly.

The Prognostic Impact of Radiotherapy Delays in Oropharynx Carcinoma and the Role of p16 Status

OBJECTIVE

A retrospective analysis was performed to evaluate the prognostic significance of treatment delays (TDs) for oropharynx carcinoma patients treated with definitive radiotherapy (RT), comparing p16+ versus p16- disease.

MATERIALS AND METHODS

Patients treated between 2012 and 2016 were analyzed (n=763). TD was defined as the time from pathologic diagnosis to initiation of RT. TD thresholds of ≤60, 61 to 90, and >90 days were used to stratify outcomes. Time on treatment (TOT) delays were estimated based on the RT fractionation. TOT delay of 1 to 3 days was compared with >3 days. Predictors of cancer-specific survival (CSS) and locoregional recurrence (LRR) were evaluated on multivariable analysis.

RESULTS

Six hundred fifty (85%) patients had p16+ disease. On multivariable analysis, TOT delay of 1 to 3 days versus <1 day was associated with inferior CSS (hazard ratio [HR]=1.81; 95% confidence interval [CI]: 1.02-3.22). TD >90 versus ≤60 days (HR=1.68; 95% CI: 0.98-3.04) and 61 to 90 versus ≤60 days (HR=0.94; 95% CI: 0.60-1.48) was not associated with CSS. TD >90 versus ≤60 days (HR=1.29; 95% CI: 0.66-2.52), TD 61 to 90 versus ≤60 days (HR=0.98; 95% CI: 0.64-1.52), TOT 1 to 3 versus <1 day (HR=0.91; 95% CI: 0.39-2.11), and TOT >3 versus <1 day (HR=1.79; 95% CI: 0.80-3.99) were not associated with LRR. There was no interaction between p16 status and TD in relation to LRR (P=0.27) or CSS (P=0.17).

CONCLUSIONS

TDs were not significantly associated with CSS or LRR. TOT of 1 to 3 days was associated with inferior CSS. p16 status should not be a significant factor when triaging RT start dates.

Evaluation of Efficacy and Tolerance of Radical Radiotherapy and Radiochemotherapy in Treatment of Locally Advanced, Unresectable Rectal Cancer

Background: A retrospective evaluation of tolerance and efficacy of two schemes of neoadjuvant treatment in patients (pts) with unresectable rectal cancer: radiochemotherapy (CRT) and radiotherapy (RT), including conventional and accelerated hyperfractionation. Material and Method: A total of 145 consecutive pts with unresectable, locally advanced rectal cancer. The schemes used are RT in 73 (50%) or CRT in 72 (50%). In CRT, 54 Gy in 1.8 Gy fractions was given with chemotherapy, In the RT group, conventional fractionation (CFRT) and hyperfractionated accelerated radiotherapy (HART). HART was introduced at first as an alternative to CFRT, after radiobiological studies suggesting a therapeutic gain of hyperfractionation in other cancers, and second to administer relatively high dose needed in unresectable cancer, which is not feasible in hypofractionation because of critical organs sensitivity to high fraction doses (fd). HART was an alternative option in pts with medical contraindications to chemotherapy and to shorten overall treatment time with greater radiobiological effectiveness than CFRT. Results: Objective response (OR) in the RT and CRT group was 60% versus 75%. Resection rate (RR) in RT and CRT: 37% versus 65%. Tumor mobility and laparotomy-based unresectability were significant factors for OR. Performance status (PS), tumor mobility, and neoadjuvant treatment method were significant for RR.

Hemoglobin A1c level is a prognostic factor for locoregional recurrence in stage III non-small cell lung cancer patients treated with radiotherapy

Background

The level of hemoglobin A1c (HbA1c) might be associated with the severity of tumor hypoxia in patients with cancer. Here, we evaluated the association between the level of HbA1c and survival outcome in stage III non‐small cell lung cancer patients treated with radical radiotherapy.

Methods

We retrospectively analysed the clinical data of 104 patients with lung cancer treated with radiotherapy. The HbA1c levels of all patients were checked 1 week before the start of radiotherapy. Survival outcomes were analysed according to the HbA1c level.

Results

The 1‐, 2‐, and 3‐year locoregional recurrence‐free survival rates were 88.3%, 68.8%, and 63.0%, respectively, in the patient group with HbA1c levels ≤6% and 75.5%, 54.4%, and 41.8%, respectively, in the patient group with HbA1c levels >6% (p = 0.015). The HbA1c level remained a significant prognostic factor for locoregional recurrence‐free survival on multivariable analysis (hazard ratio = 2.014, 95% confidence interval = 1.088–3.726, p = 0.026).

Conclusions

Pretreatment HbA1c level is a significant prognostic factor for locoregional recurrence‐free survival in patients with stage III non‐small cell lung cancer treated with radical radiotherapy. Routine monitoring of pretreatment HbA1c levels and aggressive glycemic control may be considered to prevent the development of locoregional recurrence in these patients.

Long-Term Results of Postoperative Hypofractionated Accelerated Breast and Lymph Node Radiotherapy (HypoAR) with Hypofractionated Boost

We report long-term results (median follow-up 12 years) of hypofractionated accelerated radiotherapy (HypoAR) in patients treated with breast-conserving surgery. In total, 367 women were treated with HypoAR. Axillary and supraclavicular area (ASA) were treated in patients with involved nodes. In total, 290 patients (scheme A) received 3.5 Gy/day ×10 fractions (breast/ASA) followed by two 4 Gy fractions with electrons to the affected breast quadrant within 16 days. In total, 77 patients (Scheme B) received 2.7 Gy/day for 16 consecutive fractions (breast/ASA) within 22 days, while concurrently, the affected breast quadrant received an electron booster dose of 0.8 Gy for the first 13 fractions. Amifostine was offered to 252/367 patients. Early radiation toxicity was minimal. Regarding late toxicities, symptomatic breast edema was noted in 2.2%, asymptomatic breast fibrosis in 1.9%, and arm lymphedema in 3.7% of patients. Amifostine reduced early radiation dermatitis (p = 0.001). In total, 2.2% of patients developed contralateral breast and 1.6% other carcinomas. Locoregional recurrence (LR) occurred in 3.1% of patients (0% for in situ carcinomas). Positive margins after surgery, extracapsular node invasion, and HER2-enriched/triple-negative tumors were linked with significantly worse LR-free survival. The involvement of more than three nodes and luminal type other than A were independent prognostic variables of metastasis and death events. HypoAR delivering a biological dose of 50–52 Gy to the breast/ASA is a safe and effective therapy for patients treated with conservative surgery. The risk of carcinogenesis is low. Positive surgical margins, extracapsular node invasion, and HER2-enriched/triple-negative phenotypes appear as a cluster of features linked with a higher risk for locoregional relapse.

Single-Institute Clinical Experiences Using Whole-Field Simultaneous Integrated Boost (SIB) Intensity-Modulated Radiotherapy (IMRT) and Sequential IMRT in Postoperative Patients With Oral Cavity Cancer (OCC)

This study aimed to review clinical experiences using whole-field simultaneous integrated boost (SIB) intensity-modulated radiotherapy (IMRT) and sequential IMRT in postoperative patients with oral cavity cancer (OCC). From November 2006 to December 2014, a total of 182 postoperative patients with OCC who underwent either SIB-IMRT (n = 63) or sequential IMRT (n = 119) were enrolled retrospectively and matched randomly according to multiple risk factors by a computer. The differences were well balanced after patient matching (P = .38). The median follow-up time was 65 months. For patients treated with the SIB technique and the sequential technique, the respective mortality rates were 36.8% and 20.0% (P = .04). The primary recurrence rates were 26.3% and 10.0% (P = .02), respectively. The respective marginal failure rates were 26.7% and 16.7%. A multivariate logistic regression analysis showed that patients who received the SIB technique had a 2.74 times higher risk of death than those who received the sequential technique (95% confidence interval = 1.10-6.79, P = .03). Sequential IMRT provided a significantly lower dose to the esophagus (5.2 Gy, P = .02) and trachea (4.6 Gy, P = .03) than SIB-IMRT. For patients with locally advanced OCC, postoperative sequential IMRT may overcome an unpredictable geographic miss, potentially with a lower marginal failure rate in the primary area. Patients treated by sequential IMRT show equal overall survival benefits to those treated by SIB-IMRT and a lower mortality rate than those treated by SIB-IMRT. Additionally, a reduced dose to the esophagus and trachea compared to sequential IMRT was noted.

A unified multi-activation (UMA) model of cell survival curves over the entire dose range for calculating equivalent doses in stereotactic body radiation therapy (SBRT), high dose rate brachytherapy (HDRB), and stereotactic radiosurgery (SRS)

PURPOSE

Application of linear-quadratic (LQ) model to large fractional dose treatments is inconsistent with observed cell survival curves having a straight portion at high doses. We have proposed a unified multi-activation (UMA) model to fit cell survival curves over the entire dose range that allows us to calculate EQD2 for hypofractionated SBRT, SRT, SRS, and HDRB.

METHODS

A unified formula of cell survival S = n / e D D o + n - 1 using only the extrapolation number of n and the dose slope of D_o was derived. Coefficient of determination, R² , relative residuals, r, and relative experimental errors, e, normalized to survival fraction at each dose point, were calculated to quantify the goodness in modeling of a survival curve. Analytical solutions for α and β, the coefficients respectively describe the linear and quadratic parts of the survival curve, as well as the α/β ratio for the LQ model and EQD2 at any fractional doses were derived for tumor cells undertaking any fractionated radiation therapy.

RESULTS

Our proposed model fits survival curves of in-vivo and in-vitro tumor cells with R²  > 0.97 and r < e. The predicted α, β, and α/β ratio are significantly different from their values in the LQ model. Average EQD2 of 20-Gy SRS of glioblastomas and melanomas metastatic to the brain, 10-Gy × 5 SBRT of the lung cancer, and 7-Gy × 5 HDRB of endometrial and cervical carcinomas are 36.7 (24.3-48.5), 114.1 (86.6-173.1),, and 45.5 (35-52.6) Gy, different from the LQ model estimates of 50.0, 90.0, and 49.6 Gy, respectively.

CONCLUSION

Our UMA model validated through many tumor cell lines can fit cell survival curves over the entire dose range within their experimental errors. The unified formula theoretically indicates a common mechanism of cell inactivation and can estimate EQD2 at all dose levels.

Simultaneous Integrated Boost Radiotherapy in Unresectable Stage IV (M0) Head and Neck Squamous Cell Cancer Patients: Daily Clinical Practice

AIM

To evaluate clinical outcome in locally-advanced stage IV (M0) head and neck cancer patients treated using intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) in daily clinical practice.

BACKGROUND

Despite SIB-IMRT has been reported as a feasible and effective advanced head and neck cancer treatment, there are few data about its concurrent use with systemic therapies.

MATERIAL AND METHODS

We reviewed 41 staged IV (M0) head and neck cancer patients treated in two radiotherapy units in the city of Messina (Italy) during the last six years, using intensity modulated techniques-SIB. 22/41 patients had concomitant chemotherapy or cetuximab. Acute and late toxicities, objective response (OR) rate, local control (LC) and overall survival (OS) have been evaluated.

RESULTS

37/41 patients received the planned doses of radiotherapy, 2 patients died during the therapy. The major acute regional toxicities were skin reaction and mucositis. A case of mandibular osteoradionecrosis was recorded. At completion of treatment, OR was evaluated in 38 patients: 32/38 patients (84.2%) had complete (55.3%) and partial (28.9%) response. The 1- and 5-year LC rates were 73.4% and 69.73%, respectively. The 1-, 3-, and 5-year OS rates were 85.93%, 51.49% and 44.14%, respectively. No statistically significant differences in outcomes have been observed in patients treated with radiotherapy alone vs. irradiation concomitant to chemo/biotherapy. The median OS was 45 months.

CONCLUSION

SIB-IMRT is safeand can be used with concomitant chemotherapy/biotherapy in real-life daily clinical practice. SIB-IMRT alone is a valid alternative in patients unfit for systemic therapies.

Treatment outcomes in oropharynx cancer patients who did not complete planned curative radiotherapy

PURPOSE

To evaluate outcomes in oropharyngeal cancer (OPC) patients who did not complete their planned curative radiation therapy (RT).

METHODS

OPC Patients who received less than planned curative RT dose between 2002 and 2016 were identified for analysis. HPV status was assessed. Radiation dose was normalized for fractionation variations using biological effective doses assuming tumor α/β = 10 Gy [BED10]. Outcomes were compared using BED10. Multivariable and univariable analysis identified OS predictors.

RESULTS

From a total of 80 patients who did not complete therapy, 64 patients were eligible for analysis. RT incompletion was due to: RT side effects (n = 23), patients' decision (n = 21), disease progression or metastases (n = 3), and other causes (n = 7). Median BED10 (Gy) was 56.2 for the HPV-positive and 58 for the HPV-negative. Three-year OS was 74% vs 13% (p < 0.001) for the HPV-positive (n = 29) and HPV-negative (n = 24), respectively. HPV-positive patients who received BED10 ≥55 had higher OS than those received BED10 <55 (94% vs 47%, p = 0.002) while no difference in OS by BED10 ≥55 vs <55 for the HPV-negative (12 vs 13%, p = NS). HPV-positive status was associated with a higher OS (HR 12.5, 95% CI, 4.54 to 33.3, p < 0.001). A total of 37 patients were available to estimate TD₅₀ for local control assessment. TD₅₀ (BED10) was estimated at 60.5 Gy for HPV-negative patients compared to 27.2 Gy for HPV-positive patients.

CONCLUSION

Overall, in patients with incomplete treatment, HPV-positive OPC patients demonstrated a better OS compared to HPV-negative patients. HPV-positive patients who received BED10 ≥55 have higher rates of OS.

A comparison of clinical outcomes between simultaneous integrated boost (SIB) versus sequential boost (SEQ) intensity modulated radiation therapy (IMRT) for head and neck cancer: A meta-analysis

BACKGROUND

The optimal intensity modulated radiation therapy (IMRT) technique for head and neck cancer (HNC) has not been determined yet. The present study aimed to compare the clinical outcomes of the simultaneous integrated boost (SIB)-IMRT versus the sequential boost (SEQ)-IMRT in HNC.

METHODS

A meta-analysis of 7 studies involving a total of 1049 patients was carried out to compare the treatment outcomes together with severe acute adverse effects of the SIB-IMRT versus the SEQ-IMRT in HNC patients.

RESULTS

Comparison of the SIB-IMRT and SEQ-IMRT showed no significant difference in the measurement of overall survival (OS) (hazard ratio [HR] 0.94; 95% confidence inerval [CI], 0.70-1.27; P = .71), progression free survival (PFS) (HR 1.03; 95% CI, 0.82-1.30; P = .79), locoregional recurrence free survival (LRFS) (HR 0.98; 95% CI, 0.65-1.47; P = .91), and distance metastasis free survival (DMFS) (HR 0.87; 95% CI, 0.50-1.53; P = .63). Moreover, there were no significant differences in adverse effect occurrence between the SIB-IMRT and SEQ-IMRT groups.

CONCLUSION

SIB-IMRT and SEQ-IMRT can provide comparable outcomes in the treatment of patients afflicted by HNC. Both IMRT techniques were found to carry a similar risk of severe acute adverse effect. SIB-IMRT may have advantages due to its convenience and short-course of treatment; however, the optimum fractionation and prescribed dose remained unclear. Furthermore, both IMRT techniques can be advocated as the technique of choice for HNC. Treatment plan should be individualized for patients.

Accelerated vs. conventionally fractionated adjuvant radiotherapy in high-risk head and neck cancer: a meta-analysis

Background

Adjuvant radiotherapy in advanced head and neck squamous cell cancer (HNSCC) reduces the risk of local-regional failure and most likely increases the survival rate. Patients at high risk for tumor recurrence may benefit from more aggressive altered fractionation schedules in order to reduce the overall time from surgery to completion of radiotherapy. Here, we reviewed the results of six randomized trials addressing the above hypothesis.

Methods

In the six trials of interest, a total of 988 patients with locally advanced HNSCC were randomly assigned to receive either accelerated or conventionally fractionated adjuvant radiotherapy. Hazard ratios (HR) were extracted from available publications for local-regional control, distant metastasis as well as overall-, cancer specific- and disease-free survival. Meta-analysis of the effect sizes was performed using fixed and random effect models. Acute and late side effects were categorized and summarized for comparison.

Results

Accelerated radiotherapy did not improve the loco-regional control (n = 988, HR = 0.740, CI = 0.48–1.13, p = 0.162), progression-free survival (HR = 0.89, CI = 0.76–1.04, p = 0.132) or overall survival (HR = 0.88, CI = 0.75–1.04, p = 0.148) significantly. Acute confluent mucositis occurred with significant higher frequency with accelerated radiotherapy. Late side effects did not differ significantly in either group.

Conclusion

Accelerated radiotherapy does not result in a significant improvement of loco-regional control or overall survival in high-risk patients. Acute but not late radiation toxicity were more frequent with the accelerated RT technique. In clinical practice accelerated postoperative radiation therapy might be a suitable option only for a subset of patients.

Continuous hyperfractionated accelerated radiotherapy using modern radiotherapy techniques for nonsmall cell lung cancer patients unsuitable for chemoradiation

INTRODUCTION

The continuous hyperfractionated and accelerated radiotherapy (CHART) regimen of radiotherapy (RT) for nonsmall cell lung cancer is underused outside the UK. We present the first Indian experience of using CHART for patients, who were not suitable for chemotherapy or concurrent chemo-RT.

METHODS

We retrospectively reviewed the data of patients treated using CHART at our institution between January 2014 and December 2015.

RESULTS

Thirty-seven patients were treated using CHART. Planning methods and dosimetry parameters are described. Three-dimensional conformal RT was used for treatment planning and delivery in 23 patients and volumetric modulated arc RT was necessary for 14 patients. Patients in our series had a median age of 70 years (interquartile range 65.50-74.00) and 86.5% had Stage III disease. Median follow-up was short at 13.0 months. Actuarial rates of 1-year progression-free survival, 1-year overall survival (OS), and 2-year OS were 31.9%, 59.5%, and 28.5%, respectively. This treatment was well tolerated with manageable and some reversible acute esophageal toxicity (91.9% CONCLUSION: Our results indicate that CHART is feasible, safe, and well tolerated in Indian patients who are clinically found to be not suitable for either sequential or concurrent chemo- RT.

The alfa and beta of tumours: a review of parameters of the linear-quadratic model, derived from clinical radiotherapy studies

BACKGROUND

Prediction of radiobiological response is a major challenge in radiotherapy. Of several radiobiological models, the linear-quadratic (LQ) model has been best validated by experimental and clinical data. Clinically, the LQ model is mainly used to estimate equivalent radiotherapy schedules (e.g. calculate the equivalent dose in 2 Gy fractions, EQD₂), but increasingly also to predict tumour control probability (TCP) and normal tissue complication probability (NTCP) using logistic models. The selection of accurate LQ parameters α, β and α/β is pivotal for a reliable estimate of radiation response. The aim of this review is to provide an overview of published values for the LQ parameters of human tumours as a guideline for radiation oncologists and radiation researchers to select appropriate radiobiological parameter values for LQ modelling in clinical radiotherapy.

METHODS AND MATERIALS

We performed a systematic literature search and found sixty-four clinical studies reporting α, β and α/β for tumours. Tumour site, histology, stage, number of patients, type of LQ model, radiation type, TCP model, clinical endpoint and radiobiological parameter estimates were extracted. Next, we stratified by tumour site and by tumour histology. Study heterogeneity was expressed by the I² statistic, i.e. the percentage of variance in reported values not explained by chance.

RESULTS

A large heterogeneity in LQ parameters was found within and between studies (I² > 75%). For the same tumour site, differences in histology partially explain differences in the LQ parameters: epithelial tumours have higher α/β values than adenocarcinomas. For tumour sites with different histologies, such as in oesophageal cancer, the α/β estimates correlate well with histology. However, many other factors contribute to the study heterogeneity of LQ parameters, e.g. tumour stage, type of LQ model, TCP model and clinical endpoint (i.e. survival, tumour control and biochemical control).

CONCLUSIONS

The value of LQ parameters for tumours as published in clinical radiotherapy studies depends on many clinical and methodological factors. Therefore, for clinical use of the LQ model, LQ parameters for tumour should be selected carefully, based on tumour site, histology and the applied LQ model. To account for uncertainties in LQ parameter estimates, exploring a range of values is recommended.

The alfa and beta of tumours: a review of parameters of the linear-quadratic model, derived from clinical radiotherapy studies

Background

Prediction of radiobiological response is a major challenge in radiotherapy. Of several radiobiological models, the linear-quadratic (LQ) model has been best validated by experimental and clinical data. Clinically, the LQ model is mainly used to estimate equivalent radiotherapy schedules (e.g. calculate the equivalent dose in 2 Gy fractions, EQD₂), but increasingly also to predict tumour control probability (TCP) and normal tissue complication probability (NTCP) using logistic models. The selection of accurate LQ parameters α, β and α/β is pivotal for a reliable estimate of radiation response. The aim of this review is to provide an overview of published values for the LQ parameters of human tumours as a guideline for radiation oncologists and radiation researchers to select appropriate radiobiological parameter values for LQ modelling in clinical radiotherapy.

Methods and materials

We performed a systematic literature search and found sixty-four clinical studies reporting α, β and α/β for tumours. Tumour site, histology, stage, number of patients, type of LQ model, radiation type, TCP model, clinical endpoint and radiobiological parameter estimates were extracted. Next, we stratified by tumour site and by tumour histology. Study heterogeneity was expressed by the I² statistic, i.e. the percentage of variance in reported values not explained by chance.

Results

A large heterogeneity in LQ parameters was found within and between studies (I² > 75%). For the same tumour site, differences in histology partially explain differences in the LQ parameters: epithelial tumours have higher α/β values than adenocarcinomas. For tumour sites with different histologies, such as in oesophageal cancer, the α/β estimates correlate well with histology. However, many other factors contribute to the study heterogeneity of LQ parameters, e.g. tumour stage, type of LQ model, TCP model and clinical endpoint (i.e. survival, tumour control and biochemical control).

Conclusions

The value of LQ parameters for tumours as published in clinical radiotherapy studies depends on many clinical and methodological factors. Therefore, for clinical use of the LQ model, LQ parameters for tumour should be selected carefully, based on tumour site, histology and the applied LQ model. To account for uncertainties in LQ parameter estimates, exploring a range of values is recommended.

Electronic supplementary material

The online version of this article (10.1186/s13014-018-1040-z) contains supplementary material, which is available to authorized users.

Altered Fractionation in Radiotherapy

Differences between late-responding (slowly proliferating) normal tissues and early-responding (rapidly proliferating) normal tissues and tumor cells and the event of tumor cell repopulation occurring during treatment have essentially led to the development of altered fractionation schemes. Altered fractionation regimens mainly refer to schedules utilising two or more (small dose) fractions per day for part of or for the entire treatment course. It must be underlined that a true standard or conventional fractionation regimen does not exist: no schedule is universally recognised as the standard of reference to be compared with. However, continental European and U.S. conventional regimens are the considered control arm with which the new experimental regimens have to be compared. For this reason they are generally recognised as the standards. The basic rationale for hyperfractionated or accelerated regimens respectively lies in the possibility (a) to deliver higher total doses reducing late-responding normal tissue damage, (b) to deliver total doses in a reduced overall treatment time to defeat tumor clonogen repopulation. Multiple fractions per day should not be delivered with interfraction intervals smaller than 6 hours. Clinical results of phase I-II and limited but convincing phase III randomised trials suggest that a therapeutic benefit can be achieved with new altered regimens.

Accelerated Bifractionated Radiation with Concurrent Cisplatin Administration in Locally Advanced Head and Neck Cancer: A Feasibility Study

Aims and Background

To test the feasibility of accelerated interrupted twice-daily radiation and concurrent cisplatin administration in patients with locally advanced head and neck cancer.

Patients and Methods

Nineteen patients with locally advanced head and neck cancer were treated with accelerated bifractionated radiation with concurrent administration of cisplatin. There were 18 men and 1 female with a median age of 60 years (range, 17–71) and median performance status of 90 (-range, 80–100). Sixteen patients (85%) presented with stage IV disease. Primary site included the nasopharynx (n = 7), oropharynx (n = 5), hypopharynx (n = 1) and larynx (n = 6). Radiation consisted of two fractions of 1.6 Gy each daily, five times weekly to a total dose of 64 Gy. Cisplatin was administered at a dose of 100 mg/m2 on days 2 and 28 of the treatment period.

Results

Nine patients achieved a complete response (47%; 95% CI, 25%–70%) and 5 a partial response (26%; 95% CI, 7%–46%). Grade III–IV toxicity included leukopenia (16%), mucositis (26%), dry mouth (5%), weight loss (16%) and infection (5%). After a median follow-up of 27.11 months (range, 1–33+), 9 patients have died. Median time to progression was 11 months (range, 1–32+) and median survival 25 months (range, 1–32+).

Conclusions

Accelerated twice-daily radiation with concurrent cisplatin is effective in locally advanced head and neck cancer and can be safely given with manageable toxicity.

Decision support systems for personalized and participative radiation oncology

A paradigm shift from current population based medicine to personalized and participative medicine is underway. This transition is being supported by the development of clinical decision support systems based on prediction models of treatment outcome. In radiation oncology, these models 'learn' using advanced and innovative information technologies (ideally in a distributed fashion - please watch the animation: http://youtu.be/ZDJFOxpwqEA) from all available/appropriate medical data (clinical, treatment, imaging, biological/genetic, etc.) to achieve the highest possible accuracy with respect to prediction of tumor response and normal tissue toxicity. In this position paper, we deliver an overview of the factors that are associated with outcome in radiation oncology and discuss the methodology behind the development of accurate prediction models, which is a multi-faceted process. Subsequent to initial development/validation and clinical introduction, decision support systems should be constantly re-evaluated (through quality assurance procedures) in different patient datasets in order to refine and re-optimize the models, ensuring the continuous utility of the models. In the reasonably near future, decision support systems will be fully integrated within the clinic, with data and knowledge being shared in a standardized, dynamic, and potentially global manner enabling truly personalized and participative medicine.

A comparative analysis between sequential boost and integrated boost intensity-modulated radiation therapy with concurrent chemotherapy for locally-advanced head and neck cancer

BACKGROUND

Planning and delivery of IMRT for locally advanced head and neck cancer (LAHNC) can be performed using sequential boost or simultaneous integrated boost (SIB). Whether these techniques differ in treatment-related outcomes including survival and acute and late toxicities remain largely unexplored.

METHODS

We performed a single institutional retrospective matched cohort analysis on patients with LAHNC treated with definitive chemoradiotherapy to 69.3 Gy in 33 fractions. Treatment was delivered via sequential boost (n = 68) or SIB (n = 141). Contours, plan evaluation, and toxicity assessment were performed by a single experienced physician. Toxicities were graded weekly during treatment and at 3-month follow up intervals. Recurrence-free survival, disease-free survival, and overall survival were estimated via Kaplan-Meier statistical method.

RESULTS

At 4 years, the estimated overall survival was 69.3% in the sequential boost cohort and 76.8% in the SIB cohort (p = 0.13). Disease-free survival was 63 and 69% respectively (p = 0.27). There were no significant differences in local, regional or distant recurrence-free survival. There were no significant differences in weight loss (p = 0.291), gastrostomy tube placement (p = 0.494), or duration of gastrostomy tube dependence (p = 0.465). Rates of acute grade 3 or 4 dysphagia (82% vs 55%) and dermatitis (78% vs 58%) were significantly higher in the SIB group (p < 0.001 and p = 0.012 respectively). Moreover, a greater percentage of the SIB cohort did not receive the prescribed dose due to acute toxicity (7% versus 0, p = 0.028).

CONCLUSIONS

There were no differences in disease related outcomes between the two treatment delivery approaches. A higher rate of grade 3 and 4 radiation dermatitis and dysphagia were observed in the SIB group, however this did not translate into differences in late toxicity. Additional investigation is necessary to further evaluate the acute toxicity differences.

A secretome analysis reveals that PPARα is upregulated by fractionated-dose γ-irradiation in three-dimensional keratinocyte cultures

Studies have shown that γ-irradiation induces various biological responses, including oxidative stress and apoptosis, as well as cellular repair and immune system responses. However, most such studies have been performed using traditional two-dimensional cell culture systems, which are limited in their ability to faithfully represent in vivo conditions. A three-dimensional (3D) environment composed of properly interconnected and differentiated cells that allow communication and cooperation among cells via secreted molecules would be expected to more accurately reflect cellular responses. Here, we investigated γ-irradiation-induced changes in the secretome of 3D-cultured keratinocytes. An analysis of keratinocyte secretome profiles following fractionated-dose γ-irradiation revealed changes in genes involved in cell adhesion, angiogenesis, and the immune system. Notably, peroxisome proliferator-activated receptor-α (PPARα) was upregulated in response to fractionated-dose γ-irradiation. This upregulation was associated with an increase in the transcription of known PPARα target genes in secretome, including angiopoietin-like protein 4, dermokine and kallikrein-related peptide 12, which were differentially regulated by fractionated-dose γ-irradiation. Collectively, our data imply a mechanism linking γ-irradiation and secretome changes, and suggest that these changes could play a significant role in the coordinated cellular responses to harmful ionizing radiation, such as those associated with radiation therapy. This extension of our understanding of γ-irradiation-induced secretome changes has the potential to improve radiation therapy strategies.

Tumor control probability modeling for stereotactic body radiation therapy of early-stage lung cancer using multiple bio-physical models

This work is to analyze pooled clinical data using different radiobiological models and to understand the relationship between biologically effective dose (BED) and tumor control probability (TCP) for stereotactic body radiotherapy (SBRT) of early-stage non-small cell lung cancer (NSCLC). The clinical data of 1-, 2-, 3-, and 5-year actuarial or Kaplan-Meier TCP from 46 selected studies were collected for SBRT of NSCLC in the literature. The TCP data were separated for Stage T1 and T2 tumors if possible, otherwise collected for combined stages. BED was calculated at isocenters using six radiobiological models. For each model, the independent model parameters were determined from a fit to the TCP data using the least chi-square (χ²) method with either one set of parameters regardless of tumor stages or two sets for T1 and T2 tumors separately. The fits to the clinic data yield consistent results of large α/β ratios of about 20Gy for all models investigated. The regrowth model that accounts for the tumor repopulation and heterogeneity leads to a better fit to the data, compared to other 5 models where the fits were indistinguishable between the models. The models based on the fitting parameters predict that the T2 tumors require about additional 1Gy physical dose at isocenters per fraction (⩽5 fractions) to achieve the optimal TCP when compared to the T1 tumors. In conclusion, this systematic analysis of a large set of published clinical data using different radiobiological models shows that local TCP for SBRT of early-stage NSCLC has strong dependence on BED with large α/β ratios of about 20Gy. The six models predict that a BED (calculated with α/β of 20) of 90Gy is sufficient to achieve TCP⩾95%. Among the models considered, the regrowth model leads to a better fit to the clinical data.

Six-year analysis of compliance to weekly concurrent chemoradiotherapy in head and neck carcinomas

OBJECTIVES

To evaluate treatment compliance to weekly concurrent chemoradiotherapy (CRT) in head and neck squamous cell carcinoma (HNSCC).

STUDY DESIGN

Retrospective analysis.

SETTING

Tertiary care hospital.

MAIN OUTCOME MEASURES

Overall treatment time (OTT), acute radiation morbidity and treatment completion rate without prolongation of overall treatment time of more than 2 days.

RESULTS

Three hundred and seventy-eight head and neck carcinoma patients treated with radical CRT with 70 Gy/35 fractions of radiotherapy with weekly cisplatin 40 mg/m(2) were included in the study. Median age was 52 years (range 22-77 years), oropharynx was most commonly (54%) involved site, and 55% were in stage IV disease. Majority (86%) of patients were able to complete cancer-directed therapy, median OTT was 52 days (46-140 days). Nineteen per cent of patients completed treatment without prolongation of OTT beyond 2 days and 68% of patients there completed treatment prolongation of OTT beyond 7 days. Nearly, sixty-six of the patients experienced grade II or higher acute radiation morbidities.

CONCLUSIONS

Delivery of weekly low-dose concurrent CRT is safe and feasible. Two-thirds of the patients experienced treatment prolongation of more than 2 days and 14% could not complete treatment. Results within in the study suggest to a greater need to lay emphasis on continuity of a course of radical CRT for HNSCC.

Long-term results of chemoradiotherapy for stage II-III thoracic esophageal cancer in a single institution after 2000 -with a focus on comparison of three protocols

Background

To evaluate the long-term results of chemoradiotherapy (CRT) for stage II-III thoracic esophageal cancer mainly by comparing results of three protocols retrospectively.

Methods

Between 2000 and 2012, 298 patients with stage II-III thoracic esophageal cancer underwent CRT. Patients in Group A received two cycles of cisplatin (CDDP) at 70 mg/m² (day 1 and 29) and 5-fluorouracil (5-FU) at 700 mg/m²/24 h (day 1–4 and 29–32) with radiotherapy (RT) of 60 Gy without a break. Patients in Group B received two cycles of CDDP at 40 mg/m² (day 1, 8, 36 and 43) and 5-FU at 400 mg/m²/24 h (day 1–5, 8–12, 36–40 and 43–47) with RT of 60 Gy with a 2-week break. Patients in Group C received two cycles of nedaplatin at 70 mg/m² (day 1 and 29) and 5-FU at 500 mg/m²/24 h (day 1–4 and 29–32) with RT of 60–70 Gy without a break. Differences in prognostic factors between the groups were analyzed by univariate and multivariate analyses.

Results

The 5-year overall survival rates for patients in Group A, Group B and Group C were 52.4, 45.2 and 37.2 %, respectively. The 5-year overall survival rates for patients in Stage II, Stage III (non-T4) and Stage III (T4) were 64.0, 40.1 and 22.5 %, respectively. The 5-year overall survival rates for patients who received 1 cycle and 2 cycles of concomitant chemotherapy were 27.9 and 46.0 %, respectively. In univariate analysis, stage, performance status and number of concomitant chemotherapy cycles were significant prognostic factors (p < 0.001, p = 0.008 and p < 0.001, respectively). In multivariate analysis, stage, protocol and number of concomitant chemotherapy cycles were significant factors (p < 0.001, p = 0.043 and p < 0.001, respectively).

Conclusions

The protocol used in Group A may be an effective protocol of CRT for esophageal cancer. It may be important to complete the scheduled concomitant chemotherapy with the appropriate intensity of CRT.

A proliferation saturation index to predict radiation response and personalize radiotherapy fractionation

BACKGROUND

Although altered protocols that challenge conventional radiation fractionation have been tested in prospective clinical trials, we still have limited understanding of how to select the most appropriate fractionation schedule for individual patients. Currently, the prescription of definitive radiotherapy is based on the primary site and stage, without regard to patient-specific tumor or host factors that may influence outcome. We hypothesize that the proportion of radiosensitive proliferating cells is dependent on the saturation of the tumor carrying capacity. This may serve as a prognostic factor for personalized radiotherapy (RT) fractionation.

METHODS

We introduce a proliferation saturation index (PSI), which is defined as the ratio of tumor volume to the host-influenced tumor carrying capacity. Carrying capacity is as a conceptual measure of the maximum volume that can be supported by the current tumor environment including oxygen and nutrient availability, immune surveillance and acidity. PSI is estimated from two temporally separated routine pre-radiotherapy computed tomography scans and a deterministic logistic tumor growth model. We introduce the patient-specific pre-treatment PSI into a model of tumor growth and radiotherapy response, and fit the model to retrospective data of four non-small cell lung cancer patients treated exclusively with standard fractionation. We then simulate both a clinical trial hyperfractionation protocol and daily fractionations, with equal biologically effective dose, to compare tumor volume reduction as a function of pretreatment PSI.

RESULTS

With tumor doubling time and radiosensitivity assumed constant across patients, a patient-specific pretreatment PSI is sufficient to fit individual patient response data (R(2) = 0.98). PSI varies greatly between patients (coefficient of variation >128 %) and correlates inversely with radiotherapy response. For this study, our simulations suggest that only patients with intermediate PSI (0.45-0.9) are likely to truly benefit from hyperfractionation. For up to 20 % uncertainties in tumor growth rate, radiosensitivity, and noise in radiological data, the absolute estimation error of pretreatment PSI is <10 % for more than 75 % of patients.

CONCLUSIONS

Routine radiological images can be used to calculate individual PSI, which may serve as a prognostic factor for radiation response. This provides a new paradigm and rationale to select personalized RT dose-fractionation.

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.

Effectiveness of PET/CT with (18)F-fluorothymidine in the staging of patients with squamous cell head and neck carcinomas before radiotherapy

AIM

The aim of our study was to compare the staging of the disease declared before anticancer treatment was begun with the staging that was found after the planning PET/CT scanning with (18)F-FLT was performed.

BACKGROUND

PET/CT in radiotherapy planning of head and neck cancers can facilitate the contouring of the primary tumour and the definition of metastatic lymph nodes.

MATERIALS AND METHODS

Between November 2010 and November 2013, 26 patients suffering from head and neck carcinomas underwent planning PET/CT examination with (18)F-FLT. We compared the staging of the disease and the treatment strategy declared before and after (18)F-FLT-PET/CT was performed.

RESULTS

The findings from (18)FLT-PET/CT led in 22 patients to a change of staging: in 19 patients it led to upstaging of the disease and in 3 patients it led to downstaging of the disease. In one patient, a secondary malignancy was found.

CONCLUSIONS

We have confirmed in this study that the use of (18)F-FLT-PET/CT scanning in radiotherapy planning of squamous cell head and neck carcinomas has a great potential in the precise evaluation of disease staging and consequently in the precise determination of target volumes.

Hypoxia imaging with [18F]-FMISO-PET for guided dose escalation with intensity-modulated radiotherapy in head-and-neck cancers

BACKGROUND AND PURPOSE

Positron emission tomography (PET) with [(18)F]-fluoromisonidazole ([(18)F]-FMISO) provides a non-invasive assessment of hypoxia. The aim of this study is to assess the feasibility of a dose escalation with volumetric modulated arc therapy (VMAT) guided by [(18)F]-FMISO-PET for head-and-neck cancers (HNC).

PATIENTS AND METHODS

Ten patients with inoperable stages III-IV HNC underwent [(18)F]-FMISO-PET before radiotherapy. Hypoxic target volumes (HTV) were segmented automatically by using the fuzzy locally adaptive Bayesian method. Retrospectively, two VMAT plans were generated delivering 70 Gy to the gross tumour volume (GTV) defined on computed tomography simulation or 79.8 Gy to the HTV. A dosimetric comparison was performed, based on calculations of tumour control probability (TCP), normal tissue complication probability (NTCP) for the parotid glands and uncomplicated tumour control probability (UTCP).

RESULTS

The mean hypoxic fraction, defined as the ratio between the HTV and the GTV, was 0.18. The mean average dose for both parotids was 22.7 Gy and 25.5 Gy without and with dose escalation respectively. FMISO-guided dose escalation led to a mean increase of TCP, NTCP for both parotids and UTCP by 18.1, 4.6 and 8% respectively.

CONCLUSION

A dose escalation up to 79.8 Gy guided by [(18)F]-FMISO-PET with VMAT seems feasible with improvement of TCP and without excessive increase of NTCP for parotids.

What would be the most appropriate α/β ratio in the setting of stereotactic body radiation therapy for early stage non-small cell lung cancer

We hypothesize that the correlation between the radiation dose expressed as the biologically effective dose (BED) and the clinical endpoints will correlate better as the value of the α/β ratio is increased to >10 Gy, which theoretically minimizes the overestimation of the dose potency associated with the linear quadratic (LQ) formula in the setting of stereotactic body radiation therapy (SBRT) for early stage non-small cell lung cancer (NSCLC). A search was conducted in the PubMed electronic databases in August 2011. In the studies analyzed, increasing the α/β ratio is associated with an increase in the strength of the correlation between isocenter BED and local control, especially in the studies with median followup of ≥24 months, for which Spearman's correlation coefficients of 0.74-0.76 were achieved for α/β of 20 Gy, 30 Gy, and 50 Gy (P =  0.007-0.008). A trend toward statistical significance was observed for the correlation of isocenter BED and the 2-year overall survival when an α/β of 20 Gy was used approached statistical significance (P = 0.073). Our results suggest that an α/β > 10 Gy may be more appropriate for the prediction of dose response in the setting of lung SBRT.

[IMRT and head and neck tumors: does differential fractionation have a role?]

For head and neck cancer, intensity-modulated radiation therapy (IMRT) provides benefits in terms of coverage of the target tumour volume and reduction of the dose to organs at risk. Altered fractionation called SMART (simultaneous modulated accelerated radiation therapy) or SIB (simultaneous integrated boost), equivalent to the "concomitant boost" of conventional techniques, provides additional theoretical gain in the therapeutic index and simplifies the practical implementation of the treatment. The impact on tumour control and acute and late toxicities is encouraging but needs to be confirmed by prospective clinical studies with sufficient follow-up. A lot of different protocols have been tested without really bringing out a "gold standard". However, the current results tend to suggest a SIB/SMART-IMRT moderately accelerated without combined chemotherapy for limited stages (I and II), and SIB-IMRT slightly accelerated with induction and/or concomitant chemotherapy for more advanced stages (III and IV).

Monitoring tumor proliferative response to radiotherapy using (18)F-fluorothymidine in human head and neck cancer xenograft in comparison with Ki-67

OBJECTIVE

Although radiotherapy is an important treatment strategy for head and neck cancers, it induces tumor repopulation which adversely affects therapeutic outcome. In this regard, fractionated radiotherapy is widely applied to prevent tumor repopulation. Evaluation of tumor proliferative activity using (18)F-fluorothymidine (FLT), a noninvasive marker of tumor proliferation, may be useful for determining the optimal timing of and dose in the repetitive irradiation. Thus, to assess the potentials of FLT, we evaluated the sequential changes in intratumoral proliferative activity in head and neck cancer xenografts (FaDu) using FLT.

METHODS

FaDu tumor xenografts were established in nude mice and assigned to control and two radiation-treated groups (10 and 20 Gy). Tumor volume was measured daily. (3)H-FLT was injected intravenously 2 h before killing. Mice were killed 6, 24, 48 h, and 7 days after the radiation treatment. Intratumoral (3)H-FLT level was visually and quantitatively assessed by autoradiography. Ki-67 immunohistochemistry (IHC) was performed.

RESULTS

In radiation-treated mice, the tumor growth was significantly suppressed compared with the control group, but the tumor volume in these mice gradually increased with time. In the visual assessment, intratumoral (3)H-FLT level diffusely decreased 6 h after the radiation treatment and then gradually increased with time, whereas no apparent changes were observed in Ki-67 IHC. Six hours after the radiation treatment at 10 and 20 Gy, the intratumoral (3)H-FLT level markedly decreased to 45 and 40 % of the control, respectively (P < 0.0001 vs control), and then gradually increased with time. In each radiation-treated group, the (3)H-FLT levels at 48 h and on day 7 were significantly higher than that at 6 h. The intratumoral (3)H-FLT levels in both treated groups were 68 and 60 % at 24 h (P < 0.001), 71 and 77 % at 48 h (P < 0.001), and 83 and 81 % on day 7 (P = NS) compared with the control group.

CONCLUSION

Intratumoral FLT uptake level markedly decreased at 6 h and then gradually increased with time. Sequential evaluation of intratumoral proliferative activity using FLT can be beneficial for determining the optimal timing of and dose in repetitive irradiation of head and neck cancer.

Predicting outcomes in radiation oncology--multifactorial decision support systems

With the emergence of individualized medicine and the increasing amount and complexity of available medical data, a growing need exists for the development of clinical decision-support systems based on prediction models of treatment outcome. In radiation oncology, these models combine both predictive and prognostic data factors from clinical, imaging, molecular and other sources to achieve the highest accuracy to predict tumour response and follow-up event rates. In this Review, we provide an overview of the factors that are correlated with outcome-including survival, recurrence patterns and toxicity-in radiation oncology and discuss the methodology behind the development of prediction models, which is a multistage process. Even after initial development and clinical introduction, a truly useful predictive model will be continuously re-evaluated on different patient datasets from different regions to ensure its population-specific strength. In the future, validated decision-support systems will be fully integrated in the clinic, with data and knowledge being shared in a standardized, instant and global manner.

The HYP-RT hypoxic tumour radiotherapy algorithm and accelerated repopulation dose per fraction study

The HYP-RT model simulates hypoxic tumour growth for head and neck cancer as well as radiotherapy and the effects of accelerated repopulation and reoxygenation. This report outlines algorithm design, parameterisation and the impact of accelerated repopulation on the increase in dose/fraction needed to control the extra cell propagation during accelerated repopulation. Cell kill probabilities are based on Linear Quadratic theory, with oxygenation levels and proliferative capacity influencing cell death. Hypoxia is modelled through oxygen level allocation based on pO₂ histograms. Accelerated repopulation is modelled by increasing the stem cell symmetrical division probability, while the process of reoxygenation utilises randomised pO₂ increments to the cell population after each treatment fraction. Propagation of 10⁸ tumour cells requires 5–30 minutes. Controlling the extra cell growth induced by accelerated repopulation requires a dose/fraction increase of 0.5–1.0 Gy, in agreement with published reports. The average reoxygenation pO₂ increment of 3 mmHg per fraction results in full tumour reoxygenation after shrinkage to approximately 1 mm. HYP-RT is a computationally efficient model simulating tumour growth and radiotherapy, incorporating accelerated repopulation and reoxygenation. It may be used to explore cell kill outcomes during radiotherapy while varying key radiobiological and tumour specific parameters, such as the degree of hypoxia.

Quantification of the effect of treatment duration on local-regional failure after definitive concurrent chemotherapy and intensity-modulated radiation therapy for squamous cell carcinoma of the head and neck

BACKGROUND

The purpose of this study was to quantify the effect of treatment duration on locoregional progression after definitive concurrent chemoradiation (CCRT) for squamous cell carcinoma of the head and neck (SCCHN).

METHODS

We conducted a retrospective chart review of patients treated between 2004 and 2010. After a prior analysis, measures were taken to limit therapy beyond 7 weeks. Comparison of outcomes were made between cohorts 1 (2004-2007, n = 78) and 2 (2007-2010, n = 62).

RESULTS

Median therapy duration was statistically significantly different between cohorts as follows: 51 days, cohort 1 and 46 days, cohort 2 (p < .01). Locoregional progression in cohorts 1 and 2 was 19% and 5% (p = .01), respectively. On multivariate analysis, patients with prolonged treatment (≥57 days) had an 8-fold increase in risk of locoregional progression compared to patients who completed on time (p < .01).

CONCLUSION

Treatment duration was a significant predictor of locoregional progression in patients with SCCHN who received definitive CCRT.

Monte Carlo radiotherapy simulations of accelerated repopulation and reoxygenation for hypoxic head and neck cancer

OBJECTIVE

A temporal Monte Carlo tumour growth and radiotherapy effect model (HYP-RT) simulating hypoxia in head and neck cancer has been developed and used to analyse parameters influencing cell kill during conventionally fractionated radiotherapy. The model was designed to simulate individual cell division up to 10(8) cells, while incorporating radiobiological effects, including accelerated repopulation and reoxygenation during treatment.

METHOD

Reoxygenation of hypoxic tumours has been modelled using randomised increments of oxygen to tumour cells after each treatment fraction. The process of accelerated repopulation has been modelled by increasing the symmetrical stem cell division probability. Both phenomena were onset immediately or after a number of weeks of simulated treatment.

RESULTS

The extra dose required to control (total cell kill) hypoxic vs oxic tumours was 15-25% (8-20 Gy for 5 × 2 Gy per week) depending on the timing of accelerated repopulation onset. Reoxygenation of hypoxic tumours resulted in resensitisation and reduction in total dose required by approximately 10%, depending on the time of onset. When modelled simultaneously, accelerated repopulation and reoxygenation affected cell kill in hypoxic tumours in a similar manner to when the phenomena were modelled individually; however, the degree was altered, with non-additive results. Simulation results were in good agreement with standard linear quadratic theory; however, differed for more complex comparisons where hypoxia, reoxygenation as well as accelerated repopulation effects were considered.

CONCLUSION

Simulations have quantitatively confirmed the need for patient individualisation in radiotherapy for hypoxic head and neck tumours, and have shown the benefits of modelling complex and dynamic processes using Monte Carlo methods.

Improved tumour response prediction with equivalent uniform dose in pre-clinical study using direct intratumoural infusion of liposome-encapsulated ¹⁸⁶Re radionuclides

Crucial to all cancer therapy modalities is a strong correlation between treatment and effect. Predictability of therapy success/failure allows for the optimization of treatment protocol and aids in the decision of whether additional treatment is necessary to prevent tumour progression. This work evaluated the relationship between cancer treatment and effect for intratumoural infusions of liposome-encapsulated ¹⁸⁶Re to head and neck squamous cell carcinoma xenografts of nude rats. Absorbed dose calculations using a dose-point kernel convolution technique showed significant intratumoural dose heterogeneity due to the short range of the beta-particle emissions. The use of three separate tumour infusion locations improved dose homogeneity compared to a single infusion location as a result of a more uniform radioactivity distribution. An improved dose-response correlation was obtained when using effective uniform dose (EUD) calculations based on a generic set of radiobiological parameters (R² = 0.84) than when using average tumour absorbed dose (R² = 0.22). Varying radiobiological parameter values over ranges commonly used for all types of tumours showed little effect on EUD calculations, which suggests that individualized parameter use is of little significance as long as the intratumoural dose heterogeneity is taken into consideration in the dose-response relationship. The improved predictability achieved when using EUD calculations for this cancer therapy modality may be useful for treatment planning and evaluation.

Hypoxia imaging with [F-18] FMISO-PET in head and neck cancer: potential for guiding intensity modulated radiation therapy in overcoming hypoxia-induced treatment resistance

BACKGROUND AND PURPOSE

Positron emission tomography (PET) imaging with [F-18] fluoromisonidazole (FMISO) has been validated as a hypoxic tracer. Head and neck cancer exhibits hypoxia, inducing aggressive biologic traits that impart resistance to treatment. Delivery of modestly higher radiation doses to tumors with stable areas of chronic hypoxia can improve tumor control. Advanced radiation treatment planning (RTP) and delivery techniques such as intensity modulated radiation therapy (IMRT) can deliver higher doses to a small volume without increasing morbidity. We investigated the utility of co-registered FMISO-PET and CT images to develop clinically feasible RTPs with higher tumor control probabilities (TCP).

MATERIALS AND METHODS

FMISO-PET images were used to determine hypoxic sub-volumes for boost planning. Example plans were generated for 10 of the patients in the study who exhibited significant hypoxia. We created an IMRT plan for each patient with a simultaneous integrated boost (SIB) to the hypoxic sub-volumes. We also varied the boost for two patients.

RESULT

A significant (mean 17%, median 15%) improvement in TCP is predicted when the modest additional boost dose to the hypoxic sub-volume is included.

CONCLUSION

Combined FMISO-PET imaging and IMRT planning permit delivery of higher doses to hypoxic regions, increasing the predicted TCP (mean 17%) without increasing expected complications.

Direct intratumoral infusion of liposome encapsulated rhenium radionuclides for cancer therapy: effects of nonuniform intratumoral dose distribution

PURPOSE

Focused radiation therapy by direct intratumoral infusion of lipid nanoparticle (liposome)-carried beta-emitting radionuclides has shown promising results in animal model studies; however, little is known about the impact the intratumoral liposomal radionuclide distribution may have on tumor control. The primary objective of this work was to investigate the effects the intratumoral absorbed dose distributions from this cancer therapy modality have on tumor control and treatment planning by combining dosimetric and radiobiological modeling with in vivo imaging data.

METHODS

99mTc-encapsulated liposomes were intratumorally infused with a single injection location to human head and neck squamous cell carcinoma xenografts in nude rats. High resolution in vivo planar imaging was performed at various time points for quantifying intratumoral retention following infusion. The intratumoral liposomal radioactivity distribution was obtained from 1 mm resolution pinhole collimator SPECT imaging coregistered with CT imaging of excised tumors at 20 h postinfusion. Coregistered images were used for intratumoral dosimetric and radiobiological modeling at a voxel level following extrapolation to the therapeutic analogs, 186Re/ 18Re liposomes. Effective uniform dose (EUD) and tumor control probability (TCP) were used to assess therapy effectiveness and possible methods of improving upon tumor control with this radiation therapy modality.

RESULTS

Dosimetric analysis showed that average tumor absorbed doses of 8.6 Gy/MBq (318.2 Gy/mCi) and 5.7 Gy/MBq (209.1 Gy/mCi) could be delivered with this protocol of radiation delivery for 186Re/188Re liposomes, respectively, and 37-92 MBq (1-2.5 mCi)/g tumor administered activity; however, large intratumoral absorbed dose heterogeneity, as seen in dose-volume histograms, resulted in insignificant values of EUD and TCP for achieving tumor control. It is indicated that the use of liposomes encapsulating radionuclides with higher energy beta emissions, dose escalation through increased specific activity, and increasing the number of direct tumor infusion sites improve tumor control. For larger tumors, the use of multiple infusion locations was modeled to be much more efficient, in terms of activity usage, at improving EUD and TCP to achieve a tumoricidal effect.

CONCLUSIONS

Direct intratumoral infusion of beta-emitting radionuclide encapsulated liposomes shows promise for cancer therapy by achieving large focally delivered tumor doses. However, the results of this work also indicate that average tumor dose may underestimate tumoricidal effect due to substantial heterogeneity in intratumoral liposomal radionuclide distributions. The resulting intratumoral distribution of liposomes following infusion should be taken into account in treatment planning and evaluation in a clinical setting for an optimal cancer therapy.

[Current therapy options in recurrent head and neck cancer]

Recurrent disease is one of the main reasons for the persistently poor prognosis of squamous cell carcinoma of the head and neck (HNSCC; European 5-year survival, 42%). The main treatment option for primary and secondary malignancy as well as recurrent disease is surgical therapy. If R0 resection (resection margin >5 mm) for a primary tumor is not viable, survival probability is reduced by 50%. In recurrent or secondary tumors with R1- or -2 resection or in the presence of non-resectable metastases, a palliative situation results in more than 80% of cases. In the case of surgery following radiotherapy or radiochemotherapy, attention should be paid to the criteria for salvage surgery (tissue perfusion, fibrosis, wound healing) and the procedure adapted to focus on functionality. In the case of relapse, primary surgery can potentially be supplemented with adjuvant therapy protocols such as (re-) irradiation, as well as possibly with chemotherapeutic agents or targeted therapies. Interdisciplinary collaboration and case discussions should take place in the context of a tumor board.

[Accelerated postoperative radiotherapy in patients with advanced larynx cancer]

AIM

The aim of study was test efficacy of accelerated postoperative radiotherapy--concomitant boost in patients with advanced larynx cancer.

METHODS AND MATERIALS

The prospective study included 112 patients with advanced larynx cancer after radical surgical treatment. Patients had postoperative radiation therapy, conventional (C) or accelerated (CB).

RESULTS

The 3-year overall survival in CB was 59%, in C--58% (p = 0.2), 3-year locoregional control in CB--83%, in C--75% (p = 0.01), the 3-year disease free survival was in CB--72%, C--66% (p = 0.1).

CONCLUSION

Concomitant boost postoperative radiation therapy did not improve overall survival, loco-regional control, disease free survival. Patients with close surgical margins, longer interval between surgery and radiation, high level of hemoglobin, T4 had benefit from accelerated radiotherapy.

Treatment Interruptions in Radiation Therapy for Head-and-Neck Cancer: Rates and Causes

BACKGROUND AND PURPOSE

Extending the period over which a course of radiation therapy is delivered can have detrimental effects on treatment success. This is especially true for fast growing tumors of the head-and-neck region. The goal of this study was to establish the rates and causes of treatment interruptions for head-and-neck patients at the Vancouver Cancer Centre of the BC Cancer Agency, and to explore the link between emotional distress and missed appointments.

METHODS

Head-and-neck patients who had missed treatments other than public holidays were identified using the Oncology Reporting System. The charts of these patients were pulled and examined for cause of treatment interruption. The Psychosocial Screen for Cancer (PSSCAN) found in these patients' charts was used to establish anxiety and depression levels. A random sample of PSSCANs from the charts of patients who had not missed appointments was recorded for comparison.

RESULTS

Of the 471 head-and-neck patients included in our analysis, 74% had interruptions in treatment. Gaps of greater than three days were present in 11% of treatment courses. The most common cause of treatment breaks was statutory holidays, responsible for 69% of interruptions. The anxiety and depression scores of patients who had missed appointments for reasons other than holidays were not significantly higher than patients who had not missed appointments.

CONCLUSION

Rates of treatment time extension in Vancouver were higher than expected, given rates reported from other parts of the world. Policies aimed at reducing or compensating for treatment interruptions have been successful elsewhere, and could also be instituted here. Although many published studies have shown emotional distress can lead to noncompliance in health care, this link was not found here. Several weaknesses in our study design may have contributed to the lack of correlation between anxiety and depression and missed appointments.

From cell population models to tumor control probability: including cell cycle effects

BACKGROUND

Classical expressions for the tumor control probability (TCP) are based on models for the survival fraction of cancer cells after radiation treatment. We focus on the derivation of expressions for TCP from dynamic cell population models. In particular, we derive a TCP formula for a generalized cell population model that includes the cell cycle by considering a compartment of actively proliferating cells and a compartment of quiescent cells, with the quiescent cells being less sensitive to radiation than the actively proliferating cells.

METHODS

We generalize previously derived TCP formulas of Zaider and Minerbo and of Dawson and Hillen to derive a TCP formula from our cell population model. We then use six prostate cancer treatment protocols as a case study to show how our TCP formula works and how the cell cycle affects the tumor treatment.

RESULTS

The TCP formulas of Zaider-Minerbo and of Dawson-Hillen are special cases of the TCP formula presented here. The former one represents the case with no quiescent cells while the latter one assumes that all newly born cells enter a quiescent cell phase before becoming active. From our case study, we observe that inclusion of the cell cycle lowers the TCP.

CONCLUSION

The cell cycle can be understood as the sequestration of cells in the quiescent compartment, where they are less sensitive to radiation. We suggest that our model can be used in combination with synchronization methods to optimize treatment timing.