Effect on tumour control of time interval between surgery and postoperative radiotherapy: an empirical approach using Monte Carlo simulation

Delays Starting Postoperative Radiotherapy Among Head and Neck Cancer Patients: A Systematic Review and Meta-analysis

OBJECTIVE

Initiating postoperative radiotherapy (PORT) within 6 weeks (42 days) of surgery is the first and only Commission on Cancer (CoC) approved quality metric for head and neck squamous cell carcinoma (HNSCC). No study has systematically reviewed nor synthesized the literature to establish national benchmarks for delays in starting PORT.

DATA SOURCES

Following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, we performed a systematic review of PubMed, Scopus, and CINAHL.

REVIEW METHODS

Studies that described time-to-PORT or PORT delays in patients with HNSCC treated in the United States after 2003 were included. Meta-analysis of proportions and continuous measures was performed on nonoverlapping datasets to examine the pooled frequency of PORT delays and time-to-PORT.

RESULTS

Thirty-six studies were included in the systematic review and 14 in the meta-analysis. Most studies utilized single-institution (n = 17; 47.2%) or cancer registry (n = 16; 44.4%) data. Twenty-five studies (69.4%) defined PORT delay as >6 weeks after surgery (the definition utilized by the CoC and National Comprehensive Cancer Network Guidelines), whereas 4 (11.1%) defined PORT delay as a time interval other than >6 weeks, and 7 (19.4%) characterized time-to-PORT without defining delay. Meta-analysis revealed that 48.6% (95% confidence interval [CI], 41.4-55.9) of patients started PORT > 6 weeks after surgery. Median and mean time-to-PORT were 45.8 (95% CI, 42.4-51.4 days) and 47.4 days (95% CI, 43.4-51.4 days), respectively.

CONCLUSION

Delays in initiating guideline-adherent PORT occur in approximately half of patients with HNSCC. These meta-analytic data can be used to set national benchmarks and assess progress in reducing delays.

Automated planning stage tracking and analysis through an integrated whiteboard system

PURPOSE

One of the common challenges in delivering complex healthcare procedures such as radiation oncology is the organization and sharing of information in ways that facilitate workflow and prevent treatment delays. Within the major vendors of Oncology Information Systems (OIS) is a lack of tools and displays to assist in task timing and workflow processes. To address this issue, we developed an electronic whiteboard integrated with a local OIS to track, record, and evaluate time frames associated with clinical radiation oncology treatment planning processes.

METHODS

We developed software using an R environment hosted on a local web-server at Seattle Cancer Care Alliance (SCCA) in 2017. The planning process was divided into stages, and time-stamped moves between planning stages were recorded automatically via Mosaiq (Elekta, Sweden) Quality Check Lists (QCLs). Whiteboard logs were merged with Mosaiq-extracted diagnostic factors and evaluated for significance. Interventional changes to task time expectations were evaluated for 6 months in 2021 and compared with 6 month periods in 2018 and 2019.

RESULTS

Whiteboard/Mosaiq data from the SCCA show that treatment intent, number of prescriptions, and nodal involvement were main factors influencing overall time to plan completion. Contouring and Planning times were improved by 2.6 days (p<10^-14) and 2.5 days (p<10^-11), respectively. Overall time to plan completion was reduced by 33% (5.1 days; p<10^-11).

CONCLUSIONS

This report establishes the utility of real-time task tracking tools in a radiotherapy planning process. The whiteboard results provide data-driven evidence to add justification for practice change implementations.

American Brachytherapy Society (ABS) consensus statement for soft-tissue sarcoma brachytherapy

PURPOSE

Growing data supports the role of radiation therapy in the treatment of soft tissue sarcoma (STS). Brachytherapy has been used for decades in the management of STS and can be utilized as monotherapy or as a boost to external beam radiation. We present updated guidelines from the American Brachytherapy Society regarding the utilization of brachytherapy in the management of STS.

METHODS AND MATERIALS

Members of the American Brachytherapy Society with expertise in STS and STS brachytherapy created an updated clinical practice guideline including step-by-step details for performing STS brachytherapy based on a literature review and clinical experience.

RESULTS

Brachytherapy monotherapy should be considered for lower-recurrence risk patients or after a local recurrence following previous external beam radiation; a brachytherapy boost can be considered in higher-risk patents meeting implant criteria. Multiple dose/fractionation regimens are available, with determination based on tumor location and treatment intent. Techniques to limit wound complications are based on the type of wound closure; wound complication can be mitigated with a delay in the start of brachytherapy with immediate wound closure or by utilizing a staged reconstruction technique, which allows an earlier treatment start with a delayed wound closure.

CONCLUSIONS

These updated guidelines provide clinicians with data on indications for STS brachytherapy as well as guidelines on how to perform and deliver high quality STS brachytherapy safely with minimal toxicity.

Association of Treatment Delays With Survival for Patients With Head and Neck Cancer: A Systematic Review

Importance

Delays in the delivery of care for head and neck cancer (HNC) are a key driver of poor oncologic outcomes and thus represent an important therapeutic target.

Objective

To synthesize information about the association between delays in the delivery of care for HNC and oncologic outcomes.

Evidence Review

A systematic review of the English-language literature in PubMed/MEDLINE and Scopus published between January 1, 2007, and February 28, 2018, was performed to identify articles addressing the association between treatment delays and oncologic outcomes for patients with HNC. Articles that were included (1) addressed cancer of the oral cavity, oropharynx, hypopharynx, or larynx; (2) discussed patients treated in 2004 or later; (3) analyzed time of diagnosis to treatment initiation (DTI), time from surgery to the initiation of postoperative radiotherapy, and/or treatment package time (TPT; the time from surgery through the completion of postoperative radiotherapy); (4) included a clear definition of treatment delay; and (5) analyzed the association between the treatment time interval and an oncologic outcome measure. Quality assessment was performed using the Institute of Health Economics Quality Appraisal Checklist for Case Series Studies.

Findings

A total of 18 studies met inclusion criteria and formed the basis of the systematic review. Nine studies used the National Cancer Database and 6 studies were single-institution retrospective reviews. Of the 13 studies assessing DTI, 9 found an association between longer DTI and poorer overall survival; proposed DTI delay thresholds ranged from more than 20 days to 120 days or more. Four of the 5 studies assessing time from surgery to the initiation of postoperative radiotherapy (and all 4 studies assessing guideline-adherent time to postoperative radiotherapy) found an association between a timely progression from surgery to the initiation of postoperative radiotherapy and improved overall or recurrence-free survival. Of the 5 studies examining TPT, 4 found that prolonged TPT correlated with poorer overall survival; proposed thresholds for prolonged TPT ranged from 77 days or more to more than 100 days.

Conclusions and Relevance

Timely care regarding initiation of treatment, postoperative radiotherapy, and TPT is associated with survival for patients with HNC, although significant heterogeneity exists for defining delayed DTI and TPT. Further research is required to standardize optimal time goals, identify barriers to timely care for each interval, and design interventions to minimize delays.

Proton radiotherapy and treatment delay in head and neck squamous cell carcinoma

OBJECTIVE

For patients with head and neck squamous cell carcinoma (HNSCC), delays in the initiation of radiotherapy (RT) have been closely associated with worse outcomes. We sought to investigate whether RT modality (proton vs. photon) is associated with differences in the time to initiation of RT.

METHODS

The National Cancer Database was queried for patients diagnosed with nonmetastatic HNSCC between 2004 and 2015 who received either proton or photon RT as part of their initial treatment. Wilcoxon rank-sum and chi-square tests were used to compare continuous and categorical variables, respectively. Multivariable logistic regression was used to determine the association between use of proton RT and delayed RT initiation.

RESULTS

A total of 175,088 patients with HNSCC receiving either photon or proton RT were identified. Patients receiving proton RT were more likely to be white, reside in higher income areas, and have private insurance. Proton RT was associated with delayed RT initiation compared to photon RT (median 59 days vs. 45, P < 0.001). Receipt of proton therapy was independently associated with RT initiation beyond 6 weeks after diagnosis (adjusted OR [aOR, definitive RT] = 1.69; 95% confidence interval [CI] 1.26-2.30) or surgery (aOR [adjuvant RT] = 4.08; 95% CI 2.64-6.62). In the context of adjuvant proton RT, increases in treatment delay were associated with worse overall survival (weeks, adjusted hazard ratio = 1.099, 95% CI 1.011-1.194).

CONCLUSION

Use of proton therapy is associated with delayed RT in both the definitive and adjuvant settings for patients with HNSCC and could be associated with poorer outcomes.

LEVEL OF EVIDENCE

2b Laryngoscope, 122:0000-0000, 2019 Laryngoscope, 130:E598-E604, 2020.

Association of Survival With Shorter Time to Radiation Therapy After Surgery for US Patients With Head and Neck Cancer

Importance

Shortening the time from surgery to the start of radiation (TS-RT) is a consideration for physicians and patients. Although the National Comprehensive Cancer Network recommends radiation to start within 6 weeks, a survival benefit with this metric remains controversial.

Objective

To determine the association of delayed TS-RT with overall survival (OS) using a large cancer registry.

Design, Setting, and Participants

In this observational cohort study, 25 216 patients with nonmetastatic stages III to IV head and neck cancer were identified from the National Cancer Database (NCDB).

Exposures

Patients received definitive surgery followed by adjuvant radiation therapy, with an interval duration defined as TS-RT.

Main Outcomes and Measures

Overall survival as a function of TS-RT and the effect of clinicopathologic risk factors and accelerated fractionation.

Results

We identified 25 216 patients with nonmetastatic squamous cell carcinoma of the head and neck. There were 18 968 (75%) men and 6248 (25%) women and the mean (SD) age of the cohort was 59 (10.9) years. Of the 25 216 patients, 9765 (39%) had a 42-days or less TS-RT and 4735 (19%) had a 43- to 49-day TS-RT. Median OS was 10.5 years (95% CI, 10.0-11.1 years) for patients with a 42-days or less TS-RT, 8.2 years (95% CI, 7.4-8.6 years; absolute difference, -2.4 years, 95% CI, -1.5 to -3.2 years) for patients with a 43- to 49-day TS-RT, and 6.5 years (95% CI, 6.1-6.8 years; absolute difference, -4.1 years, 95% CI, -3.4 to -4.7 years) for those with a 50-days or more TS-RT. Multivariable analysis found that compared with a 42-days or less TS-RT, there was not a significant increase in mortality with a 43- to 49-day TS-RT (HR, 0.98; 95% CI, 0.93-1.04), although there was for a TS-RT of 50 days or more (HR, 1.07; 95% CI, 1.02-1.12). A significant interaction was identified between TS-RT and disease site. Subgroup effect modeling found that a delayed TS-RT of 7 days resulted in significantly worse OS for patients with tonsil tumors (HR, 1.22; 95% CI, 1.05-1.43) though not other tumor subtypes. Accelerated fractionation of 5.2 fractions or more per week was associated with improved survival (HR, 0.93; 95% CI, 0.87-0.99) compared with standard fractionation.

Conclusions and Relevance

Delayed TS-RT of 50 days or more was associated with worse overall survival. The multidisciplinary care team should focus on shortening TS-RT to improve survival. Unavoidable delays may be an indication for accelerated fractionation or other dose intensification strategies.

Timing of Postoperative Radiotherapy in Surgically Treated HPV-Positive Oropharyngeal Squamous Cell Carcinoma

OBJECTIVE

Optimal timing of postoperative radiotherapy (PORT) remains understudied in human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma. Objectives are to determine if delays between surgery and radiotherapy, breaks during radiotherapy, disease, or patient factors are associated with recurrence or survival decrements in HPV-related disease.

DESIGN

Retrospective review.

SETTING

Academic medical center.

SUBJECTS

A total of 240 cases of HPV-positive oropharyngeal squamous cell carcinoma from 2000 to 2016.

METHODS

Patient and tumor characteristics (American Joint Committee on Cancer, eighth edition), delays to radiation initiation, and breaks during radiation were recorded. Overall survival (OS) and recurrence-free survival (RFS) were analyzed.

RESULTS

RFS and OS were not significantly affected by delays to PORT >6 weeks or by treatment intervals >100 days (surgery to PORT completion). Breaks during PORT significantly imparted an OS detriment (hazard ratio [HR], 2.4; 95% CI, 1.2-4.8). Advanced-stage disease was significantly associated with reduced RFS and OS. Subgroup analysis of stage I versus stage II/III disease found that >6 weeks to PORT initiation and treatment intervals >100 days did not significantly decrease RFS or OS in either stage group. Advanced-stage disease was significantly associated with worsened OS (HR, 6.6; 95% CI, 2.3-19.1) and RFS (HR, 5.3; 95% CI, 1.5-18.4). Breaks during PORT significantly reduced RFS (HR, 3.6; 95% CI, 1.2-10.8) and OS (HR, 3.2; 95% CI, 1.2-9.0) in the stage II/III subset.

CONCLUSION

Delays to radiotherapy initiation and prolonged treatment time did not affect recurrence or survival in HPV-related oropharyngeal disease. Locoregionally advanced disease was consistently associated with worse outcomes. Breaks during PORT may affect recurrence and survival, although larger studies are needed to confirm this finding.

The impact of treatment package time on survival in surgically managed head and neck cancer in the United States

OBJECTIVES

Delays in the initiation of postoperative radiation have been associated with worse outcomes; however, the effect of the overall treatment package time (interval from surgery through the completion of radiation) remains undefined. The purpose of this study was to determine the impact of package time on survival and to evaluate this effect among different subgroups of head and neck cancer patients.

PATIENTS AND METHODS

In this observational cohort study, the National Cancer Database was used to identify 35,167 patients with resected nonmetastatic head and neck cancer who underwent adjuvant radiation from 2004 to 2014. Kaplan-Meier survival estimates and multivariate Cox regression analyses were performed to determine the effect of treatment package time on overall survival.

RESULTS

Median package time was 96 days (interquartile range, 85-112 days). After adjusting for covariates, package times of 11 weeks or less were associated with improved survival (adjusted hazard ratio (aHR), 0.90; 95% confidence interval, 0.83-0.97) compared to an interval of 12-13 weeks, whereas package times of more than 14 weeks were associated with worse survival (aHR, 1.14, 1.14, and 1.22 for 14-15, 15-17, and >17 weeks, respectively). A significant interaction was identified between package time and disease site, nodal status, and stage. Specifically, patients with oropharyngeal tumors, advanced stage (III or IV) disease, or nodal involvement experienced more pronounced increases in mortality risk with delays in treatment time.

CONCLUSIONS

Treatment package time independently impacts survival. This effect may be strongest for patients with oropharyngeal tumors or advanced stage disease.

Radiobiological parameters for breast cancer: a Monte Carlo analysis of START trial published results

OBJECTIVE:

Trial results are usually given in terms of end point confidence intervals, the data concerning the participating patients being not available. Sometimes, it would be useful or necessary to obtain derived quantities, such as dose-response relationships, from the known information. In this work, we describe a methodology that allows to do that and illustrate it by analyzing the UK standardization of breast radiotherapy (START) trials.

METHODS:

Using Monte Carlo techniques, virtual data sets were generated by sampling trial outcome distributions in terms of the tumor control probability (described by means of a logistic dose response and the equations of isoeffect in the linear-quadratic model). After fitting the available experimental data, the radiobiological parameters of interest and their confidence intervals were obtained from the TCP vs 'EQD2 curve in which the surgery effect is also taken into account.

RESULTS:

The value of [Formula: see text] obtained for breast cancer was 3.6 Gy, with a 95% confidence interval of (1.5,15.5) Gy, in agreement with the one estimated by the START group. The time factor, referred to a scheme of 2 Gy per fraction, was 0.74 (0.41,2.67) Gy day^-1, of the same order than that estimated for head and neck cancers.

CONCLUSION:

A methodology permitting an analysis of trial results was developed and tested with the results of the START trials. The procedure does not require detailed knowledge of the distributions actually found in the trials. The values obtained for the parameters are similar to those of the START estimations and this can be considered an independent confirmation of their validity, thus showing the model usefulness. The methodology presented here relies on basic statistical methods that are general enough to permit it to be applied to any kind of trial. This may be particularly interesting when the original data are no longer available.

ADVANCES IN KNOWLEDGE:

The main novelty of this paper is to provide with a Monte Carlo based tool that permits an independent analysis of published trial results in order to obtain radiobiological parameters without a detailed knowledge of the data corresponding to the participating patients.

Effect of time to initiation of postoperative radiation therapy on survival in surgically managed head and neck cancer

BACKGROUND

The objective of this study was to determine the effects of National Comprehensive Cancer Network (NCCN) guideline-adherent initiation of postoperative radiation therapy (PORT) and different time-to-PORT intervals on the overall survival (OS) of patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

The National Cancer Data Base was reviewed for the period of 2006-2014, and patients with HNSCC undergoing surgery and PORT were identified. Kaplan-Meier survival estimates, Cox regression analysis, and propensity score matching were used to determine the effects of initiating PORT within 6 weeks of surgery and different time-to-PORT intervals on survival.

RESULTS

This study included 41,291 patients. After adjustments for covariates, starting PORT >6 weeks postoperatively was associated with decreased OS (adjusted hazard ratio [aHR], 1.13; 99% confidence interval [CI], 1.08-1.19). This finding remained in the propensity score-matched subset (hazard ratio, 1.21; 99% CI, 1.15-1.28). In comparison with starting PORT 5 to 6 weeks postoperatively, initiating PORT earlier was not associated with improved survival (aHR for ≤ 4 weeks, 0.93; 99% CI, 0.85-1.02; aHR for 4-5 weeks, 0.92; 99% CI, 0.84-1.01). Increasing durations of delay beyond 7 weeks were associated with small, progressive survival decrements (aHR, 1.09, 1.10, and 1.12 for 7-8, 8-10, and >10 weeks, respectively).

CONCLUSIONS

Nonadherence to NCCN guidelines for initiating PORT within 6 weeks of surgery was associated with decreased survival. There was no survival benefit to initiating PORT earlier within the recommended 6-week timeframe. Increasing durations of delay beyond 7 weeks were associated with small, progressive survival decrements. Cancer 2017;123:4841-50. © 2017 American Cancer Society.

Minimizing the uncertainties regarding the effects of delaying radiotherapy for Glioblastoma: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Previous studies have provided no clear conclusions regarding the effects of delaying radiotherapy (RT) in GBM patients. We present a systematic review and meta-analysis to address the effect of delayed RT on the overall survival (OS) of GBM patients.

METHODS

A systematic search retrieved 19 retrospective studies published between 1975 and 2014 reporting on the waiting time (WT) to RT for GBM patients. The meta-analysis was performed by converting WT to RT studies intervals into a regression coefficient (β) and standard error expressing the effect size on OS per week of delay.

RESULTS

Data required to calculate the effect size on OS per week of delay were available for 12 studies (5212 patients). A non-adjusted model and a meta-regression model based on well-recognized prognostic factors were performed. No association between WT to RT, per week of delay, and OS was found (HR=0.98; 95% CI 0.90-1.08; p=0.70). The meta-regression adjusted for prognostic factors weighted by the inverse-variance (1/SE(2)) showed no clear evidence of the effect of WT to RT, per week of delay, on OS.

CONCLUSIONS

This meta-analysis, despite limitations, provided no evidence of a true effect on OS by delaying RT in GBM patients.

Empirically-based estimates for the burden of subclinical metastases

PURPOSE

To describe the frequency distribution for the number of residual subclinical metastatic tumor cells after removal of the primary cancer.

MATERIALS AND METHODS

Previously obtained autopsy, surgical pathological and laboratory data were used to characterize the size and number distributions for hematogenous and lymphatic metastases. Monte Carlo simulations were used to estimate the numbers of residual tumor cells based upon the assumption of a lognormal distribution for the sizes of metastases and Poisson, Poisson negative binomial, or negative binomial distributed numbers of metastases (corresponding to lymphatic metastases within individuals, hematogenous metastases within individuals, and lymphatic metastases within populations, respectively).

RESULTS

In each of the scenarios the resultant distribution for the numbers of subclinical tumor cells was unimodal and positively skewed, with a tail extending to the higher numbers of metastases. When plotted with equal sized counting bins and according the logarithm of the number of tumor cells, the distributions showed deviations from the normal form no greater than several percentage points--a result considered acceptable given the variabilities inherent to metastasis data.

CONCLUSIONS

The distribution for the number of residual subclinical metastases may be extrapolated from data and models derived from the size and number distributions for metastases. In the absence of a closed form description for this distribution, the lognormal distribution could provide a crude, but practical, approximation for cases limited to occult microscopic residual disease. These analyses will facilitate the definition of the dose-response for the adjuvant therapy of subclinical metastases.

Radiotherapy treatment delays and their influence on tumour control achieved by various fractionation schedules

There is often a considerable delay from initial tumour diagnosis to the start of radiotherapy treatment. This paper extends the calculations of a previous paper on the effects of delays before the initiation of radiotherapy treatment to include results from a variety of practical fractionation regimes for three different types of tumour: squamous cell carcinoma (head and neck), breast and prostate. The linear quadratic model of radiation effect, logarithmic tumour growth (coupled with delay times where relevant) and the Poisson model for tumour control probability (TCP) are used to calculate the change in TCP for delays between diagnosis and treatment. Within the limitations of radiobiological modelling, these data can be used to tentatively assess the interactions between delays, dose fractionation and TCP. The results show that delays in the start of radiotherapy treatment do have an adverse effect on tumour control for fast-growing tumours. For example, calculations predict a reduction in local tumour control of up to 1.5% per week's delay for head and neck cancers treated following surgery. In addition, there may be a variety of fractionation regimes that will yield very similar clinical results for each tumour type. It is shown theoretically that, for the tumour types considered here, it is possible to increase the dose per fraction and decrease the number of fractions while maintaining or increasing TCP relative to standard 2 Gy fractionation regimes, although there may be some advantage to using hyperfractionated regimes for head and neck cancers in order to reduce normal tissue effects.

EGFR-TK inhibition before radiotherapy reduces tumour volume but does not improve local control: Differential response of cancer stem cells and nontumourigenic cells?

BACKGROUND AND PURPOSE

Waiting times before radiotherapy may reduce tumour control probability due to proliferation of tumour cells. The aim of the experiment was to test whether the growth inhibiting effect of epidermal growth factor receptor (EGFR)-inhibitors after surgery or tumour transplantation results in a lower tumour mass at time of irradiation and can thereby improve local tumour control.

MATERIALS AND METHODS

The EGFR-tyrosine kinase inhibitor BIBX1382BS was applied over 14days starting from microscopically non-in-sano-resection of FaDu tumours or from tumour transplantation, followed by irradiation (5f/5d). Endpoint was local tumour control. In addition, vital tumour areas, pimonidazole hypoxic fraction, BrdU labelling index, and colony forming ability in vitro were tested in control tumours and after BIBX1382BS treatment (starting from transplantation).

RESULTS

The tumour volume at start of irradiation was significantly lower in the BIBX1382BS treated tumours as compared to the control groups by factors of 11 (post-surgery setting) and 2.7 (transplantation setting). However, the reduced volume did not translate into improved local control after irradiation. The TCD(50) values after surgery were 25.4Gy [95% CI 18; 33Gy] in the control group and 30.5Gy [24; 37] in the BIBX1382BS group (p=0.25). Treatment after transplantation resulted in TCD(50) values of 41.1Gy [35; 47] in the control group and 41.1Gy [33; 49] in the BIBX1382BS group (p=1). While the proportion of S-phase cells decreased after BIBX1382BS treatment, no differences were observed between the pimonidazole hypoxic fractions and in vitro colony forming ability.

CONCLUSIONS

EGFR-TK inhibition with BIBX1382BS over 14days between macroscopically complete tumour resection or tumour transplantation and start of radiotherapy significantly reduced tumour volume but did not improve local tumour control. One possible explanation is that the EGFR-TK inhibitor has a higher activity in nontumourigenic cancer cells compared to cancer stem cells. This hypothesis, along with the observation that tumours of similar size were significantly more radiosensitive after surgery than without surgery, warrants further investigation.