Quality of interstitial PDR-brachytherapy-implants of head-and-neck-cancers: predictive factors for local control and late toxicity?

Dose escalation in oropharyngeal cancer: a comparison of simultaneous integrated boost and brachytherapy boost

BACKGROUND

Local recurrence is the most common pattern of failure in head and neck cancer. It can therefore be hypothesised that some of these patients would benefit from an intensified local treatment, such as radiation dose escalation of the primary tumour. This study compares treatment and toxicity outcomes from two different boost modalities in oropharyngeal cancer: simultaneous integrated boost (SIB) and brachytherapy boost.

METHODS

Two hundred and forty-four consecutive patients treated with > 72 Gy for oropharyngeal squamous cell carcinoma between 2011 and 2018 at our institution were retrospectively analysed. Data on side effects were collected from a local quality registry and supplemented with a review of medical records. Patients receiving a brachytherapy boost first had external beam radiotherapy consisting of 68 Gy in 2 Gy fractions to the gross tumour volume (GTV), and elective radiotherapy to the neck bilaterally. The brachytherapy boost was typically given using pulsed dose rate, 15 fractions and 0.56-0.66 Gy per fraction [total dose in EQD2 = 75.4-76.8 Gy (α/β = 10)]. The typical dose escalated radiotherapy with external beam radiotherapy only, was delivered using SIB with 74,8 Gy in 2.2 Gy fractions [EQD2 = 76.0 Gy (α/β = 10)] to the primary tumour, 68 Gy in 2 Gy fractions to GTV + 10 mm margin and elective radiotherapy to the neck bilaterally.

RESULTS

Dose escalation by SIB was given to 111 patients and brachytherapy boost to 134 patients. The most common type of cancer was base of tongue (55%), followed by tonsillar cancer (42%). The majority of patients had T3- or T4-tumours and 84% were HPV-positive. The 5-year OS was 72,4% (95% CI 66.9-78.3) and the median follow-up was 6.1 years. Comparing the two different dose escalation modalities we found no significant differences in OS or PFS and these results remained after a propensity-score matched analysis was performed. The analysis of grade ≥ 3 side effects showed no significant differences between the two different dose escalation techniques.

CONCLUSIONS

We found no significant differences in survival or grade ≥ 3 side effects comparing simultaneous integrated boost and brachytherapy boost as alternative dose escalation modalities in the treatment of oropharyngeal cancer.

Results of sole postoperative interstitial, high-dose-rate brachytherapy of T1–2 tongue tumours

Purpose

To describe the results of treating tongue cancer patients with single postoperative interstitial, high-dose-rate (HDR) brachytherapy (BT) after resection.

Methods

Between January 1998 and April 2019, 45 patients with squamous cell histology, stage T1–2N0–1M0 tongue tumours were treated by surgery followed by a single HDR BT in case of negative prognostic factors (close or positive surgical margin, lymphovascular and/or perineural invasion). The average dose was 29 Gy (range: 10–45 Gy) and rigid metal needles were used in 11 (24%) and flexible plastic catheters in 34 cases (76%). Survival parameters, toxicities and the prognostic factors influencing survival were analysed.

Results

During a mean follow-up of 103 months (range: 16–260 months) for surviving patients, the 10-year local and regional control (LC, RC), overall survival (OS), and disease-specific survival (DSS) probabilities were 85, 73, 34 and 63%, respectively. The incidence of local grade 1, 2 and 3 mucositis was 23, 73 and 4%, respectively. As a serious (grade 4), late side effect, soft tissue necrosis developed in 3 cases (7%). In a univariate analysis, there was a significant correlation between lymphovascular invasion and RC (p = 0.0118) as well as cervical recurrence and DSS (p < 0.0001).

Conclusion

Sole postoperative HDR brachytherapy can be an effective method in case of negative prognostic factors in the treatment of early, resectable tongue tumours. Comparing the results of patients treated with postoperative BT to those who were managed with surgery or BT alone known from the literature, a slightly more favourable LC can be achieved with the combination therapy, demonstrating the potential compensating effect of BT on adverse prognostic factors, while the developing severe, grade 4 toxicity rate remains low.

Long term outcomes of Carcinoma Buccal Mucosa treated with High Dose Rate Interstitial Brachytherapy

PURPOSE

To analyze the long-term local control, overall survival and toxicity in Carcinoma Buccal Mucosa patients treated with interstitial brachytherapy.

METHODS AND MATERIALS

This analysis included patients diagnosed as Carcinoma Buccal Mucosa on biopsy and treated with radical brachytherapy or External Beam Radiotherapy (EBRT) followed by brachytherapy boost. All patients received High dose rate (HDR) interstitial brachytherapy. The total dose was 35 Gy in ten fractions for brachytherapy alone. Patients who received EBRT (50-54 Gy) were boosted by brachytherapy to a dose of 18-24 Gy in 6-8 fractions. All patients were treated using CT based planning.

RESULTS

Between 2007 to 2017, a total of 24 patients of Carcinoma Buccal Mucosa received HDR interstitial brachytherapy either alone or as a boost. Majority of the patients were tobacco chewers (80%). 17(71%) patients were clinical stage T2N0M0 and 7(29%) were clinically T1N0M0. At a median follow up of 7 years (3-12 years), the local control rate was 100% in stage I and 88% in stage II. The 5 year overall survival rate was 80%. Two patients developed nodal recurrence and one patient developed distant metastasis within two years of treatment. Tumor size and brachytherapy technique (radical vs. boost) did not impact local control or overall survival (p > 0.05). Majority of the acute toxicities were Grade 1 and 2. One patient developed osteoradionecrosis of the mandible.

CONCLUSIONS

Interstitial brachytherapy in early-stage Buccal Mucosa cancer either alone or as a boost provides excellent long term local control and overall survival. The acute and late toxicities are acceptable with majority of the patients presenting with Grade 1 or 2 toxicity.

Brachytherapy in head and neck malignancies: Indian Brachytherapy Society (IBS) recommendations and guidelines

PURPOSE

Brachytherapy (BT) forms major treatment modality in squamous cell carcinoma of head and neck cancers (HNC). However, there is a dearth of literature and guidelines for the use in various indications. High-dose-rate brachytherapy (HDR-BT) in Indian scenario is an important treatment modality, and the recommendations in this guidelines aim to provide the necessary recommendations for the use of HDR-BT for uniform application across the country in patients with HNC.

MATERIAL AND METHODS

A panel consisting of members of the Indian Brachytherapy Society (IBS), based on their clinical experience was invited. The process involved defining important steps, precautions, target volumes and indications, thorough literature review, and discussion with fellow members. The guidelines were established and formulated the recommendations for HDR-BT based on available evidences and individual experience for sites, relevant to Indian settings.

RESULTS

The IBS recommends the use of HDR brachytherapy as a part of treatment of head and neck tumors. The scope of these guidelines and recommendations included practical suggestions, ensuring efficient use of brachytherapy treatment as radical with external beam radiotherapy (EBRT) boost, palliative and adjuvant as definitive, or re-radiation as salvage for HNC in India. The IBS has made specific site-wise recommendations for previously untreated and recurrent HNC patients on their selection criteria, implant techniques, target volume definition, and HDR treatment parameters, such as time, dose rate, total dose, and fractionation schedules. Limited experience exists with HDR-BT in patients with head and neck cancers in India and across the globe.

CONCLUSIONS

IBS provided a consensus statement and guidelines for the head and neck brachytherapy and believed that these recommendations will overcome the fear of practicing radiation oncologists. This should generate interest amongst students and will help radiation oncologists all across the country to use the art of brachytherapy carefully in HNC patients, with better curative and salvage options.

Dose volume histogram constraints in patients with head and neck cancer treated with surgery and adjuvant HDR brachytherapy: A proposal of the head and neck and skin GEC ESTRO Working group

BACKGROUND

The Head and Neck and Skin (HNS) Working group of the GEC-ESTRO acknowledges the lack of widely accepted Dose Volume Histogram (DVH) constraints in adjuvant head and neck brachytherapy and issues recommendations to minimize mandibular Osteoradionecrosis (ORN) and Soft Tissue Necrosis (STN).

METHODS

A total of 227 patients with the diagnosis of head and neck cancer treated with surgery and adjuvant HDR brachytherapy alone or combined with other treatment modalities during the period 2000-2018 were analyzed.

RESULTS

STN was observed in 28 out of 227 cases (12.3%) with an average time to appearance of 4.0 months. In previously unirradiated cases, there was a positive correlation between CTV size and STN (p = 0.017) and a trend towards significance between Total EQD2-DVH TV₁₀₀ dose and STN (p = 0.06). The risk of STN in the absence of both factors (i.e, CTV < 15 cm³ and Total EQD2-DVH TV₁₀₀ dose < 87 Gy) was 2%, with one factor present 15.7% and with both factors 66.7% (p = 0.001). ORN was observed in 13 out of 227 cases (5.7%) with an average time to appearance of 26.2 months. In unirradiated cases, ORN correlated with Total Physical Dose to Mandible_2cm3 (p = 0.027). Patients receiving Total Physical Doses greater than 61 Gy had a 20-fold increased risk of ORN.

CONCLUSIONS

In Unirradiated patients the panel recommends to avoid implantation of postoperative CTVs exceeding 15 cm³ at Total EQD2-DVH TV₁₀₀ doses in excess of 87 Gy as well as to limit the irradiation of the Mandible_2cm3 to 61 Gy. In previously irradiated patients the panel cannot make a recommendation based on the available results.

Second-line treatment of recurrent HNSCC: tumor debulking in combination with high-dose-rate brachytherapy and a simultaneous cetuximab-paclitaxel protocol

BACKGROUND AND PURPOSE

After the failure of first-line treatment, the clinical prognosis in head and neck cancer (HNSCC) deteriorates. Effective therapeutic strategies are limited due to the toxicity of previous treatments and the diminished tolerance of surrounding normal tissue. This study demonstrates a promising second-line regimen, with function preserving surgical tumor debulking, followed by a combination of postoperative interstitial brachytherapy and a simultaneous protocol of cetuximab and taxol.

PATIENTS AND METHODS

From January 2006 to May 2013, 197 patients with HNSCC were treated with brachytherapy at the University Hospital Schleswig-Holstein Campus Lübeck, including 94 patients due to recurrent cancer. Within these, 18 patients were referred to our clinic because of early progressive disease following first- or second-line treatment failure. They received the new palliative regimen. A matched-pair analysis including recurrent tumor stage, status of resection margins, tissue invasion and previous therapy was performed to evaluate this treatment retrospectively. Overall survival (OS), disease-free survival (DFS), functional outcome and treatment toxicity was analyzed on the basis of medical records and follow-up data.

RESULTS

DFS and OS of the study group were 8.7 and 14.8 months. Whereas, DFS and OS of the control group, treated only by function preserving tumor debulking and brachytherapy, was 3.9 and 6.1 months respectively. This demonstrates a positive trend through the additional use of the cetuximab-taxane protocol. Furthermore, no increase of therapy induced toxicities was displayed.

CONCLUSION

Pre-treated patients with a further relapse benefit from the 'cetuximab-taxane recurrency scheme'. It seems to be a valuable complement to interdisciplinary and multimodal tumor therapy, which improves OS and results in acceptable toxicity.

Modern head and neck brachytherapy: from radium towards intensity modulated interventional brachytherapy

Intensity modulated brachytherapy (IMBT) is a modern development of classical interventional radiation therapy (brachytherapy), which allows the application of a high radiation dose sparing severe adverse events, thereby further improving the treatment outcome. Classical indications in head and neck (H&N) cancers are the face, the oral cavity, the naso- and oropharynx, the paranasal sinuses including base of skull, incomplete resections on important structures, and palliation. The application type can be curative, adjuvant or perioperative, as a boost to external beam radiation as well as without external beam radiation and with palliative intention. Due to the frequently used perioperative application method (intraoperative implantation of inactive applicators and postoperative performance of radiation), close interdisciplinary cooperation between surgical specialists (ENT-, dento-maxillary-facial-, neuro- and orbital surgeons), as well interventional radiotherapy (brachytherapy) experts are obligatory. Published results encourage the integration of IMBT into H&N therapy, thereby improving the prognosis and quality of life of patients.

Comparison of intensity-modulated radiotherapy, adaptive radiotherapy, proton radiotherapy, and adaptive proton radiotherapy for treatment of locally advanced head and neck cancer

BACKGROUND AND PURPOSE

Various radiotherapy planning methods for locally advanced squamous cell carcinoma of the head and neck (SCCHN) have been proposed to decrease normal tissue toxicity. We compare IMRT, adaptive IMRT, proton therapy (IMPT), and adaptive IMPT for SCCHN.

MATERIALS AND METHODS

Initial and re-simulation CT images from 10 consecutive patients with SCCHN were used to quantify dosimetric differences between photon and proton therapy. Contouring was performed on both CTs, and plans (n=40 plans) and dose-volume histograms were generated.

RESULTS

The mean GTV volume decreased 53.4% with re-simulation. All plans provided comparable PTV coverage. Compared with IMRT, adaptive IMRT significantly reduced the maximum dose to the mandible (p=0.020) and mean doses to the contralateral parotid gland (p=0.049) and larynx (p=0.049). Compared with IMRT and adaptive IMRT, IMPT significantly lowered the maximum doses to the spinal cord (p<0.002 for both) and brainstem (p<0.002 for both) and mean doses to the larynx (p<0.002 for both) and ipsilateral (p=0.004 IMRT, p=0.050 adaptive) and contralateral (p<0.002 IMRT, p=0.010 adaptive) parotid glands. Adaptive IMPT significantly reduced doses to all critical structures compared with IMRT and adaptive IMRT and several critical structures compared with non-adaptive IMPT.

CONCLUSIONS

Although adaptive IMRT reduced dose to several normal structures compared with standard IMRT, non-adaptive proton therapy had a more favorable dosimetric profile than IMRT or adaptive IMRT and may obviate the need for adaptive planning. Protons allowed significant sparing of the spinal cord, parotid glands, larynx, and brainstem and should be considered for SCCHN to decrease normal tissue toxicity while still providing optimal tumor coverage.

Pulsed dose rate brachytherapy as the boost in combination with external beam irradiation in base of tongue cancer. Long-term results from a uniform clinical series

PURPOSE

To evaluate long time outcome with regard to local tumour control, side effects and quality of life of combined pulsed dose rate (PDR) boost and hyperfractionated accelerated external beam radiotherapy (EBRT) for primary base of tongue (BOT) cancers.

MATERIAL AND METHODS

Between 1994 and 2007, the number of 83 patients were treated with primary T1-T4 BOT cancers. Seven patients (8%) were T1-2N0 (AJCC stage I-II) and 76 (92%) patients were T1-2N+ or T3-4N0-2 (AJCC stage III-IV). The mean estimated primary tumour volume was 15.4 (1-75) cm3. EBRT was given with 1.7 Gy bid to 40.8 Gy to primary tumour and bilateral neck lymph nodes in 2.5 weeks. PDR boost of 35 Gy and a neck dissection in clinical node positive case was performed 2-3 weeks later. The patients were followed for a median of 54 (2-168) months.

RESULTS

The 2-, 5- and 10-years rates of actuarial local control were 91%, 89% and 85%, overall survival 85%, 65% and 44%, disease free survival 86%, 80% and 76%, respectively. The regional control rate was 95%. Six patients (7%) developed distant metastases. A dosimetric analysis showed a mean of 100% isodose volume of 58.2 (16.7-134) cm3. In a review of late complications 11 cases of minor (13%) and 5 of major soft tissue necroses (6%), as well as 6 cases of osteoradionecroses (7%) were found. The patients median subjective SOMA/LENT scoring at last follow up was as follow: grade 0 for pain and trismus, grade 1 for dysphagia and taste alteration, and grade 2 for xerostomia. Global visual-analogue-scale (VAS) scoring of quality of life was 8.

CONCLUSION

Local and regional tumour control rate was excellent in this treatment protocol. The data shows the PDR boost as at least as effective as published continuous low dose rate (CLDR) results.

A review of in vitro experimental evidence for the effect of spatial and temporal modulation of radiation dose on response

BACKGROUND

Intensity modulated radiation therapy introduces strong spatial and temporal modulation of the dose delivery that may have therapeutic benefits, as yet unrealized.

MATERIAL AND METHODS

Experimental evidence for spatial and temporal modulation affecting the cell survival following in vitro irradiation has been derived using clonogenic assays.

RESULTS AND DISCUSSION

The experimental results show that the survival status of a cell is strongly influenced by the spatial dose modulation. The classical bystander effect of decreased survival has now been supplemented by observations of increased survival, which may result from the same or different signaling mechanisms. Temporal dose modulation experiments show that dose protraction significantly increases cell survival. An appropriate choice of temporal dose modulation pattern enables cell death to be maximized or minimized for a constant dose and delivery time.

CONCLUSION

Bystander effects challenge the assumption that outcome is solely dependent on local dose. Intra-fractional temporal modulation via protracted treatments and time varying dose delivery both affect the cell survival. The presence of bystander and temporal effects emphasize the need for a mathematical framework which incorporates their influence on cell survival.

Dose volume uniformity index: a simple tool for treatment plan evaluation in brachytherapy

Purpose

In radiotherapy treatment planning, dose homogeneity inside the target volume plays a significant role in the final treatment outcome. Especially in brachytherapy where there is a steep dose gradient in the dose distribution inside the target volume, comparing the plans based on the dose homogeneity helps in assessing the high dose volume inside the final treatment plan. In brachytherapy, the dose inhomogeneity inside the target volume depends on many factors such as the type of sources, placement of these radioactive sources, distance between the applicators/implant tubes, dwell time of the source, etc. In this study, a simple index, the dose volume uniformity index (DVUI), has been proposed to study the dose homogeneity inside the target volume. This index gives the total dose volume inhomogeneity inside a given prescription isoline.

Material and methods

To demonstrate the proposed DVUI in this study, a single plane implant (breast: 6 catheters), a double plane implant (breast: 9 catheters) and a tongue implant (5 catheters) were selected. The catheters were reconstructed from the CT image datasets in the Plato treatment planning system. The doses for the single, double and tongue implants were prescribed to the reference dose rate as per the Paris technique. DVUI was computed from the cumulative dose volume histogram.

Results

For a volume receiving a uniform dose inside the prescription isoline, the DVUI is 1. Any value of DVUI > 1 shows the presence of a relatively high dose volume inside the prescription isoline. In addition to the concept of DVUI, a simple conformality index, the dose volume conformality index (DVCI), has also been proposed in this study based on the DVUI.

Conclusion

The DVUI and the proposed DVCI in this study provide an easy way of comparing the rival plans in brachytherapy.

GEC-ESTRO recommendations for brachytherapy for head and neck squamous cell carcinomas

Both primary and recurrent squamous cell carcinoma of the head and neck are classic indications for brachytherapy. A high rate of local tumor control at the cost of limited morbidity can be achieved with brachytherapy through good patient selection, meticulous source implantation and careful treatment planning. However, no randomized trials have been performed, and there is scant evidence in the literature especially regarding practical clinical recommendations for brachytherapy for head and neck subsites. The Head and Neck Working Group of the European Brachytherapy Group (Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) therefore decided to formulate the present consensus recommendations for low-dose rate, pulsed-dose rate and high-dose rate brachytherapy. The use of brachytherapy in combination with external beam radiotherapy and/or surgery is also covered as well as the use of brachytherapy in previously irradiated patients. Given the paucity of evidence in the literature, these recommendations are mainly based on clinical experience accumulated by the members of the working group over several decades and the respective publications. The recommendations cover in a general part (1) patient selection, the pre-treatment work up and patient care, (2) treatment strategy, (3) target definition, (4) implant techniques, (5) dose and dose rate prescription, (6) treatment planning and reporting, (7) treatment monitoring (8) catheter removal, and (9) post-treatment patient care and follow-up. The recommendations are then specified for the classical brachytherapy tumor sites following an analogue more focussed structure (patient selection, implant technique, target definition, dose and dose rate prescription, results): lip, oral mucosa, mobile tongue, floor of mouth, oropharynx, nasopharynx, paranasal sinuses.