Repopulation during radical radiotherapy for T1 glottic cancer

Prognostic factors in patients with T1 glottic cancer treated with radiotherapy

PURPOSE

Presentation of long-term results of radiation treatment in patients with T1 glottic cancer and evaluation of prognostic factors.

METHODS

We performed a retrospective analysis in a group of 569 patients with T1 squamous cell glottic carcinoma treated with radiotherapy at the Center of Oncology in Cracow between 1977 and 2007. In all, 503 (88%) patients presented with T1a stage disease and 66 (12%) with T1b. Anterior commissure infiltration was present in 179 (31%) patients. Average hemoglobin level prior to therapy was 13.9 g/dl. Using the body mass index (BMI), 114 (20%) patients were underweight, and 91 (16%) were overweight. Median time between collecting tumor specimen and beginning of radiotherapy was 56 days (range 14-145 days). Treatment regimen was normofractionated with single fraction ≤2 Gy in 102 (18%) and hypofractionated in 467 (82%) patients.

RESULTS

The 5‑ and 10-year overall survival (OS), disease-specific survival (DSS) and local control (LC) rates were 85 and 68%, 88 and 86%, 89 and 87%, respectively. Multivariate analysis showed that tobacco smoking, low hemoglobin level (<13 g/dl), anterior commissure infiltration, fraction dose ≤2 Gy and time from collecting specimen to beginning of therapy longer than 30 days had negative impact on LC and DSS. Patients' age over 60 years, worse performance status and malnutrition (BMI <18.5) had negative impacts on OS.

CONCLUSIONS

Radiotherapy is a highly effective treatment method in patients with T1N0M0 glottic cancer. LC and DSS may be improved following hypofractionation, smoking cessation, and shortening of waiting-time until start of treatment. OS was mainly influenced by nutritional and performance status.

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.

A prospective randomized trial comparing hypofractionation with conventional fractionation radiotherapy for T1-2 glottic squamous cell carcinomas: results of a Korean Radiation Oncology Group (KROG-0201) study

BACKGROUND AND PURPOSE

To prospectively investigate the effect of radiotherapy fraction size on clinical outcomes in early glottic carcinoma

METHODS AND MATERIALS

Patients with T1-2 glottic carcinoma were eligible for the protocol. Although 282 patients were required, the study was closed prematurely due to poor accrual with only 156 patients. Of these, 82 patients were allocated to conventional fractionation (CONV) arm (66 Gy/33 fractions for T1 and 70 Gy/35 fractions for T2), with 74 patients to hypofractionation (HYPO) arm (63 Gy/28 fractions for T1 and 67.5 Gy/30 fractions for T2). The primary objective was local progression-free survival (LPFS).

RESULTS

With a median follow-up of 67 months (range, 2-122 months), the 5-year LPFS was 77.8% for CONV arm and 88.5% for HYPO arm (HR 1.55, p=0.213). No significant difference was observed in the toxicity profile between the two arms. In a subgroup exploratory analysis for T1a disease, the 5-year LPFS trended positively in HYPO arm (76.7% vs. 93.0%, HR 3.65, p=0.056).

CONCLUSIONS

Given that HYPO is at least not inferior to CONV with a similar toxicity profile, the hypofractionation scheme used in this study can be offered to patients with T1-2 glottic carcinoma with potential advantages in terms of local control and a shortened overall treatment time.

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.

Radical radiotherapy for early glottic cancer: Results in a series of 1087 patients from two Italian radiation oncology centers. I. The case of T1N0 disease

PURPOSE

To retrospectively evaluate local control rates, late damage incidence, functional results, and second tumor occurrence according to the different patient, tumor, and treatment features in a large bi-institutional series of T1 glottic cancer.

METHODS AND MATERIALS

A total of 831 T1 glottic cancer cases treated consecutively with radical intent at the Florence University Radiation Oncology Department (FLO) and at the Radiation Oncology Department of the University of Brescia-Istituto del Radio "O. Alberti" (BS) were studied. Actuarial cumulative local control probability (LC), disease-specific (DSS), and overall survival (OS) rates have been calculated and compared in the different clinical and therapeutic subgroups with both univariate and multivariate analysis. Types of relapse and their surgical salvage have been evaluated, along with the functional results of treatment. Late damage incidence and second tumor cumulative probability (STP) have been also calculated.

RESULTS

In the entire series, 3-, 5-, and 10-year OS was equal to 86%, 77%, and 57%, respectively. Corresponding values for LC were 86%, 84%, and 83% and for DSS 96%, 95%, and 93%, taking into account surgical salvage of relapsed cases. Eighty-seven percent of the patients were cured with function preserved. Main determinants of a worse LC at univariate analysis were: male gender, earlier treatment period, larger tumor extent, anterior commissure involvement, and the use of Cobalt 60. At multivariate analysis, only gender, tumor extent, anterior commissure involvement, and beam type retained statistical significance. Higher total doses and larger field sizes are significantly related (logistic regression) with a higher late damage incidence. Scatterplot analysis of various combinations of field dimensions and total dose showed that field dimensions >35 and <49 cm2, together with doses of >65 Gy, offer the best local control results together with an acceptably low late damage incidence. Twenty-year STP was equal to 23%, with second tumor deaths being more frequent than larynx cancer deaths (67 of 831 vs. 46/831).

CONCLUSION

The results of this study support the opinion, suggested by some international guidelines, that radiotherapy is standard treatment for T1 glottic cancer. Better results are obtained in patients with less extended disease and with 4-6 MV photon beams. The use of doses in excess of 65 Gy and of field sizes of 36-49 cm2 is probably the best technical choice available. Late damage is infrequent, but careful follow-up is warranted to detect early not only relapses (because conservative salvage surgery is feasible), but also second malignant tumors, which constitute the main cause of death in these patients and are potentially curable.

Radioresistant laryngeal cancer: beyond the TNM stage

Early stage squamous cell carcinoma of the larynx can be effectively cured by radiotherapy. Unfortunately treatment failures do occur and at present cannot be predicted by the clinician. This article reviews the potential molecular and cellular markers that may help to predict radioresistance in early stage laryngeal cancer.

The effect of waiting time on local control and survival in head and neck carcinoma patients treated with radiotherapy

PURPOSE

To determine the influence of waiting time for radiotherapy on local control and survival in a cohort of patients with head and neck carcinoma of different locations and stages treated with radiotherapy.

MATERIAL AND METHODS

Retrospective study of 797 patients with squamous cell carcinoma located in the oral cavity, pharynx or larynx, treated with radiotherapy, and with a minimum follow-up of 3 years. Local recurrence and survival were analyzed in function of the waiting time, defined as the interval between date of histologic diagnosis and date of radiotherapy. A univariate and multivariate analysis was carried out.

RESULTS

Median waiting time to radiotherapy was 44 days (25 and 75% quartiles: 33 and 60 days). There were significant differences in the waiting time period in relation to the primary location and the local extension of the tumor. Both univariate and multivariate analysis showed that waiting time had no significant impact either on local control or survival.

CONCLUSION

Within the range of the waiting time observed in our study, delay in the initiation of radiotherapy did not affect local control or survival in patients with head and neck carcinoma.

[Treatment of T1N0 glottis carcinoma with radiotherapy. Results at our center and review of the literature]

OBJECTIVE

To evaluate the results of radiotherapy in the treatment of patients with T1N0 glottic squamous cell carcinoma.

MATERIAL AND METHODS

Retrospective study of a cohort of 338 patients with T1N0 glottic carcinoma treated with radiotherapy at our institution between 1985-1997. A review of the literature published during the last ten years was carried out.

RESULTS

Local control with radiotherapy in our patients was 82%, reaching 97% when salvage surgery was included. The local control with radiotherapy in most of the published series ranges between 81.90%.

CONCLUSIONS

Treatment with radiotherapy achieves local control in early glottic carcinomas (T1N0) in 80-90% of cases. In our centre such treatment achieved local control in 82% of cases.

Hyperfractionated-accelerated or conventionally fractionated radiotherapy for early glottic cancer

PURPOSE

To evaluate the effect of shortening overall treatment time by hyperfractionated-accelerated radiotherapy for T2N(0)M(0) glottic carcinomas. Results for local control and survival were calculated and compared to those for T1N(0)M(0) tumors treated with a once-a-day fractionated schedule.

METHODS AND MATERIALS

Between 1990 and 1998, 92 patients with T1N(0)M(0) and 45 patients with T2N(0)M(0) glottic cancers were treated with radical radiotherapy. The T1N(0)M(0) tumors were treated with a once-a-day fractionated schedule lasting 6.5 weeks to a total dose of 62.4 Gy. The T2N(0)M(0) tumors received a split-course hyperfractionated-accelerated treatment over a total of 4.5 weeks to a total dose of 64.6 Gy.

RESULTS

The 5-year local control was 85% for T1N(0)M(0) and 88% for T2N(0)M(0), whereas the 5-year locoregional control was 85% for both groups. The 5-year overall survival was 70% and 53% for T1N(0)M(0) and T2N(0)M(0), respectively. No significant statistical difference was found between the two groups for the parameters analyzed. The number of serious late complications was few and comparable for the two groups.

CONCLUSIONS

Hyperfractionated-accelerated radiotherapy proved beneficial for T2N(0)M(0) glottic cancer, giving local control rates comparable to those for T1N(0)M(0) tumors.

Proliferative capacity in head and neck cancer

BACKGROUND

Shortening of overall treatment time (accelerated radiotherapy) appears to result in an increase of the efficacy of irradiation. In this study, we compared the proliferative capacity between tumors originating in different sites of the head and neck region. Tumors with a large proliferating capacity might, theoretically, benefit most from accelerated radiotherapy.

MATERIAL AND METHODS

BrdUrd was administered intravenously in patients with head and neck carcinomas. Tumor samples were analyzed with flow cytometry. T and N stages were assessed in accordance with the TNM classification system (UICC 1987).

RESULTS

No significant differences in proliferation parameters were observed with respect to site of origin of head and neck tumors. For T3/T4 tumors, DNA ploidy is an important tumor characteristic: G1- and S-phase fractions, labeling index, and tumor doubling time Tpot differences were statistically significant; the aneuploid tumors showed the largest proliferative potential.

CONCLUSIONS

(1) In general, no significant differences in proliferation parameters were observed with respect to site of origin. (2) Aneuploid head and neck tumors have a higher proliferative capacity than diploid ones, they might benefit most from accelerated irradiation.

Determination of tumor kinetics: strategies for the delivery of radiotherapy and chemotherapy

Both clinical and laboratory evidence indicates that local control rates for many experimental and clinical human tumors decrease with protraction of the overall duration of radiation therapy and that a likely basis for this decrease is tumor cell repopulation during treatment. Such observations have stimulated interest in tumor kinetics, and a number of techniques have been developed that increase the potential for meaningful clinical study of the proliferative behavior of tumors. This review discusses the clinical and experimental evidence for proliferation during treatment, describes two potential approaches-accelerated fractionation and concurrent chemotherapy and radiotherapy-that can be employed to counteract such intratreatment proliferation, explores methods available for measuring tumor cell kinetics, and discusses how kinetics information may be used in the future to tailor therapy to a tumor's individual characteristics.