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

GEC-ESTRO recommendations for head & neck cancer brachytherapy (interventional radiotherapy): 2nd update with focus on HDR and PDR

Modern brachytherapy (BT) is playing an important role in the multidisciplinary treatment of Head and Neck (H&N) cancer, as an organ- and function-preserving therapy. Low-dose-rate (LDR) technology has been replaced by modern remote afterloading and stepping source equipment using pulsed dose rate (PDR) or high dose rate (HDR) sources, improved image guidance and 3D treatment planning systems. This is an update of the previous GEC-ESTRO recommendations for H&N tumors, mainly applied to squamous carcinomas. Indications, results and recommended doses for different tumor sites are presented according to the published studies.

Inverse planning optimization with lead block effectively suppresses dose to the mandible in high-dose-rate brachytherapy for tongue cancer

PURPOSE

In this study, we developed in-house software to evaluate the effect of the lead block (LB)-inserted spacer on the mandibular dose in interstitial brachytherapy (ISBT) for tongue cancer. In addition, an inverse planning algorithm for LB attenuation was developed, and its performance in mandibular dose reduction was evaluated.

METHODS

Treatment plans of 30 patients with tongue cancer treated with ISBT were evaluated. The prescribed dose was 54 Gy/9 fractions. An in-house software was developed to calculate the dose distribution based on the American Association of Physicists in Medicine (AAPM) Task Group No.43 (TG-43) formalism. The mandibular dose was calculated with consideration of the LB attenuation. The attenuation coefficient of the lead was computed using the PHITS Monte Carlo simulation. The software further optimized the treatment plans using an attraction-repulsion model (ARM) to account for the LB attenuation.

RESULTS

Compared to the calculation in water, the D2 cc of the mandible changed by - 2.4 ± 2.3 Gy (range, - 8.6 to - 0.1 Gy) when the LB attenuation was considered. The ARM optimization with consideration of the LB resulted in a - 2.4 ± 2.4 Gy (range, - 8.2 to 0.0 Gy) change in mandibular D2 cc.

CONCLUSIONS

This study enabled the evaluation of the dose distribution with consideration of the LB attenuation. The ARM optimization with lead attenuation further reduced the mandibular dose.

Interventional Radiotherapy (Brachytherapy) for Nasal Vestibule: Novel Strategies to Prevent Side Effects

Interventional radiotherapy (brachytherapy) has become the new therapeutic standard in the management of early stages nasal vestibule tumors; in fact it allows for high local control rates and low toxicity profiles. However, since more and more patients will receive interventional radiotherapy (brachytherapy) as primary treatment, it is desirable to implement novel strategies to reduce the dose to organs at risk with the future aim to result in further lowering long-term side effects.

MATERIALS AND METHODS

We were able to identify two different strategies to reduce dose to the treatment volume, including the implantation technique (the implant can be interstitial, endocavitary or mixed and the catheters may be placed either using the Paris system rules or the anatomical approach) and the dose distribution within the implant (the most commonly used parameter to consider is the dose non-uniformity ratio). We subsequently propose two novel strategies to reduce dose to organs at risk, including the use of metal shields for fixed organs as in the case of the eyes and the use of a mouth swab to push away mobile organs, such in the case of the mandible. We used two different algorithms to verify the values namely the TG-43 and the TG-186.

RESULTS

We provided an accurate literature review regarding strategies to reduce toxicity to the treatment volume, underlining the pros and cons of all implantation techniques and about the use dose non-uniformity ratio. Regarding the innovative strategies to reduce the dose to organs at risk, we investigated the use of eye shielding and the use of swabs to push away the mandible by performing an innovative calculation using two different algorithms in a series of three consecutive patients. Our results show that the dose reduction, both in the case of the mandible and in the case of eye shielding, was statistically significant.

CONCLUSION

Proper knowledge of the best implantation technique and dose non-uniformity ratio as highlighted by existing literature is mandatory in order to reduce toxicity within the treatment volume. With regard to the dose reduction to the organs at risk we have demonstrated that the use of eye shielding and mouth swab could play a pivotal role in clinical practice; in fact, they are effective at lowering the doses to the surrounding organs and do not require any change to the current clinical workflow.

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.

Function Preservation in Head and Neck Cancers

The treatment of head and neck cancers can have a significant impact on function and appearance, which results in impairment of quality of life. Various long-term sequelae of treatment include speech and swallowing difficulty, oral incompetence, trismus, xerostomia, dental caries and osteoradionecrosis. Management has evolved from single modality treatment of either surgery or radiation to multimodality treatment to attain acceptable functional outcomes. Brachytherapy, also known as interventional radiotherapy, with its ability to deliver high doses centrally to the target, has been shown to improve local control rates. Due to the rapid fall-off of the dose of brachytherapy there is better organ at risk sparing as compared with that of external beam radiotherapy. In the head and neck region, brachytherapy has been practiced in various sites, including the oral cavity, oropharynx, nasopharynx, nasal vestibule and paranasal sinuses. Additionally, brachytherapy has also been considered for reirradiation as a salvage. Brachytherapy can also be considered as a perioperative technique together with surgery. Close multidisciplinary cooperation is required for a successful brachytherapy programme. In oral cavity cancers, depending on the location of the tumour, brachytherapy has been shown to preserve oral competence, maintain tongue mobility, maintain speech, swallowing and the hard palate. Brachytherapy in oropharyngeal cancers has been shown to reduce xerostomia and also reduce dysphagia and aspiration post-radiation therapy. For the nasopharynx, paranasal sinus and nasal vestibule, brachytherapy preserves the respiratory function of the mucosa. Despite such an incomparable impact on function and organ preservation, brachytherapy is an underutilised technique for head and neck cancers. There is a strong need to improve brachytherapy utilisation in head and neck cancers.

Is There Still a Place for Brachytherapy in the Modern Treatment of Early-Stage Oral Cancer?

Simple Summary

Brachytherapy involves the direct application of radioactive sources to the tumour. This technique is characterised by a delivery of high dose of radiation to the target volume and simultaneous sparring of healthy tissues. Historically, low-dose-rate brachytherapy played an important role in the treatment of early-stage oral cancer, with treatment outcomes that were comparable to surgery. Interest in brachytherapy as a primary treatment for oral cancer has declined in recent years due to the emergence of better surgical techniques, to advances in external beam radiotherapy, and to concerns regarding toxicity of modern high-dose-rate brachytherapy. At present, the main indications for brachytherapy are in the postoperative setting due to the superior dose conformity and better quality of life offered by brachytherapy compared to external beam radiation therapy. Postoperative brachytherapy can be administered as a monotherapy in early-stage tumours (T1N0) and in combination with elective neck dissection or EBRT to treat larger or deeper tumours. Brachytherapy yields excellent results for lip carcinoma in older patients and in tumours with unfavourable localisations. Brachytherapy is an effective salvage therapy for local recurrences in previously-irradiated areas.

Abstract

Brachytherapy (BT) involves the direct application of radioactive sources to the tumour. This technique is characterised by a steep dose gradient, the delivery of high-dose radiation to the target volume centre, and the sparing of surrounding healthy tissues. Low-dose-rate (LDR) BT and manual afterloading played an important role in the treatment of early-stage oral cancer, with treatment outcomes that were comparable to surgery. Interest in BT as a primary treatment for oral cancer has declined in recent years due to the emergence of better surgical techniques, the switch from LDR BT to high-dose-rate (HDR) BT (which has a higher risk of complications), and to advances in external beam radiotherapy (EBRT). At present, the main indications for BT are in the postoperative setting due to the superior dose conformity and better quality of life offered by BT versus EBRT. Postoperative BT can be administered as monotherapy in early-stage (T1N0) cancers and in combination with elective neck dissection or EBRT to treat larger or deeper tumours. BT yields excellent results for lip carcinoma in older patients and in tumours with unfavourable localisations. BT is an effective salvage therapy for local recurrences in previously-irradiated areas. Despite its many advantages, brachytherapy is a complex treatment requiring meticulous technique and close cooperation between the radiation oncologist, physicist, and surgeon.

Recurrent/Metastatic Squamous Cell Carcinoma of the Head and Neck: A Big and Intriguing Challenge Which May Be Resolved by Integrated Treatments Combining Locoregional and Systemic Therapies

Squamous cell carcinoma of the head and neck (SCCHN) is a complex group of malignancies, posing several challenges to treating physicians. Most patients are diagnosed with a locally advanced disease and treated with strategies integrating surgery, chemotherapy, and radiotherapy. About 50% of these patients will experience a recurrence of disease. Recurrent/metastatic SCCHN have poor prognosis with a median survival of about 12 months despite treatments. In the last years, the strategy to manage recurrent/metastatic SCCHN has profoundly evolved. Salvage treatments (surgery or re-irradiation) are commonly employed in patients suffering from locoregional recurrences and their role has gained more and more importance in the last years. Re-irradiation, using some particularly fractionating schedules, has the dual task of reducing the tumor mass and eliciting an immune response against cancer (abscopal effect). In this review, we will analyze the main systemic and/or locoregional strategies aimed at facing the recurrent/metastatic disease, underlining the enormous importance of the multidisciplinary approach in these types of patients.