Management of deep-seated malformations with photodynamic therapy: a new guiding imaging modality

From Basic Mechanisms to Clinical Research: Photodynamic Therapy Applications in Head and Neck Malignancies and Vascular Anomalies

Head and neck cancers are largely squamous cell carcinomas derived from the epithelial lining of the structures in the region, and are often classified anatomically into oral, oropharyngeal, nasopharyngeal and laryngeal carcinomas. The region’s component structures serve complex and intricate functions, such as speaking, swallowing and breathing, which are often compromised by these neoplasms. Such lesions may also cause disfigurement, leading to distressing social and psychological issues. Conventional treatments of these neoplasms usually involve surgical intervention with or without chemoradiotherapy. These have shown to be efficacious; however, they can also cause damage to healthy as well as diseased tissue, exacerbating the aforementioned problems. Access to a given region to deliver the treatments is also often a problem, due to the complex anatomical structures involved. The use of photodynamic therapy in the head and neck region has been established for about two decades. In this review, we looked at the basic mechanisms of this intervention, examined its use in common head and neck malignancies and vascular anomalies, and reported on the most recent clinical studies. We further included a clinical guide which can help replicate the use of this technology by any unit. Based on this review, photodynamic therapy has been shown to be efficacious in the treatment of head and neck malignancies and vascular tumours. This therapy can be targeted to the diseased tissue and causes no damage to underlying structures. Recent studies have shown this therapy to be as effective as conventional therapies, without causing major adverse effects.

Surface markers for guiding cylindrical diffuser fiber insertion in interstitial photodynamic therapy of head and neck cancer

BACKGROUND AND OBJECTIVES

Image-based treatment planning can be used to compute the delivered light dose during interstitial photodynamic therapy (I-PDT) of locally advanced head and neck squamous cell carcinoma (LA-HNSCC). The objectives of this work were to evaluate the use of surface fiducial markers and flexible adhesive grids in guiding interstitial placement of laser fibers, and to quantify the impact of discrepancies in fiber location on the expected light dose volume histograms (DVHs).

METHODS

Seven gel-based phantoms were made to mimic geometries of LA-HNSCC. Clinical flexible grids and fiducial markers were used to guide the insertion of optically transparent catheters, which are used to place cylindrical diffuser fibers within the phantoms. A computed tomography (CT) was used to image the markers and phantoms before and after catheter insertion and to determine the difference between the planned and actual location of the catheters. A finite element method was utilized to compute the light DVHs. Statistical analysis was employed to evaluate the accuracy of fiber placement and to investigate the correlation between the location of the fibers and the calculated DVHs.

RESULTS

There was a statistically significant difference (P = 0.018) between all seven phantoms in terms of the mean displacement. There was also statistically significant correlation between DVHs and depth of insertion (P = 0.0027), but not with the lateral displacement (P = 0.3043). The maximum difference between actual and planned DVH was related to the number of fibers (P = 0.0025) and the treatment time.

CONCLUSIONS

Surface markers and a flexible grid can be used to assist in the administration of a prescribed DVH within 15% of the target dose provided that the treatment fibers are placed within 1.3 cm of the planned depth of insertion in anatomies mimicking LA-HNSCC. The results suggest that the number of cylindrical diffuser fibers and treatment time can impact the delivered DVHs. Lasers Surg. Med. 49:599-608, 2017. © 2017 Wiley Periodicals, Inc.

Photodynamic therapy in the upper aerodigestive tract. Overview and outlook

The gold standard in the treatment of (pre)malignancies of the upper aerodigestive tract (UADT) is either surgery or (chemo)radiotherapy. Nevertheless, there are special indications where an alternative treatment, such as photodynamic therapy (PDT), might be as effective for and better tolerated by the patients concerned. This article aims to present a contemporary and comprehensive review on the role of photodynamic therapy in the treatment of (pre)malignancies of the UADT. PubMed was searched for "photodynamic therapy larynx/oral cavity/oropharynx/head and neck" in 01/2016. PDT can be efficient in the treatment of recurrent, residual or multiple carcinomas of the UADT without other treatment options. It has also been used with success in the treatment of early oral or laryngeal carcinomas, widespread precancerous lesions or "difficult-to-treat" skin cancer, even though these treatments are off-label. For now, unsolved scientific and economical challenges hinder the methods spread. In special cases, PDT is a highly effective method to treat head and neck (pre)malignancies. Nevertheless, further clinical studies are needed to better define its true value in head and neck oncology.

Photodynamic therapy in the management of lesions of the head and neck

Photodynamic therapy (PDT) is a promising and effective treatment for lesions of the head and neck. It uses illumination with light of a specific wavelength, which activates a photosensitising drug in the presence of oxygen. It can be used in combination with other treatments or on its own, and results in the cellular destruction of the lesion through a free-radical process. Photosensitisers can be applied topically or given systemically depending on the lesion being treated. Results indicate that PDT is an effective adjunct to standard conventional treatments. We review its use.

Prospective evaluation of 110 patients following ultrasound-guided photodynamic therapy for deep seated pathologies

INTRODUCTION

Photodynamic therapy, the fourth oncological interventional modality has proved its success in the management of variety of pathologies involving the human body. Our aim in this prospective clinical study was to continue evaluating the outcome following ultrasound-guided interstitial PDT of pathologies involving the human body. Patients' reports on quality of life with clinical and radiological evaluation were the main end point parameters used to assess the outcome.

MATERIALS AND METHODS

One hundred and ten patients were referred to the UCLH Head and Neck Centre, London for treatment of various deep-seated pathologies. These included tumours in the head and neck as well as vascular anomalies of the limbs. After multidisciplinary discussion, all patients underwent interstitial photodynamic therapy (iPDT) under general anaesthesia, using 0.15mg/kg mTHPC as the photosensitising agent. Following treatment, patients were followed-up for a mean of 26 months.

RESULTS

Four out of five patients who presented with visual problems reported improvement after treatment. Also, 27/32 reported improvement of breathing. Improvement of swallowing was reported by 30/37 patients; while speech improvement was evident in 22/29 patients and 43/52 reported reduction in the disfigurement caused by their pathology. Seven out of nine patients with impeded limb function reported some degree of improvement. Clinical assessment showed that nearly half of the patients had "good response" to the treatment and 5 became disease free. Moderate clinical response was reported by 39 patients. Radiological assessment comparing radiological imaging 6-week post-PDT to the baseline showed moderate response in 45 patients and significant response in 32 patients.

CONCLUSION

This study on 110 patients with deep-seated pathologies undergoing interstitial photodynamic therapy provided further evidence that PDT is a useful modality in the management of these pathologies that are otherwise resistant to conventional treatments, and with minimal side effects.

The surgical palliation of advanced head and neck cancer using photodynamic therapy

End-stage head and neck cancer is a difficult disease to manage. The only curative treatment option remains surgery, but this is frequently not feasible. Often, however, significant palliation can be achieved with minimally invasive surgically directed treatments, such as photodynamic therapy. To avoid the morbidity of treating non-cancer areas, photodynamic therapy can now be very accurately directed by radiological imaging along pre-planned grids to document and optimise laser-guided photo-activation of the chemo-sensitiser. Rapid local tumour control often results, enabling the patient to benefit from both a higher quality and length of life.

Ultrasound-guided photodynamic therapy for deep seated pathologies: prospective study

INTRODUCTION

Interstitial photodynamic therapy remains an attractive remedial option in minimally invasive surgery. Our aim in this prospective study was to evaluate the outcome following ultrasound-guided iPDT of deep-seated pathologies. Patients' reports on quality of life with clinical and radiological evaluation were the main end point parameters used to assess the outcome.

MATERIALS AND METHODS

Sixty-eight patients were referred to the UCLH Head and Neck Centre for treatment of various deep-seated pathologies involving the head and neck region, upper and lower limbs. All patients underwent interstitial photodynamic therapy under general anaesthesia, using 0.15 mg/kg mTHPC as the photosensitising agent. Following treatment, patients were followed-up for a mean of 7 months.

RESULTS

All three patients who presented with visual problems reported improvement after treatment. Also, 14/17 patients reported improvement of breathing. Improvement of swallowing was reported by 25/30 patients; while speaking improvement was evident in 16/22 patients and 33/40 reported reduction in the disfigurement caused by their pathology. All five patients with impeded limb function reported some degree of improvement. Clinical assessment showed that half of the patients had 'good response' to the treatment and a third reported 'moderate response' with two patients being free of disease. Radiological assessment comparing imaging 6-week post-PDT to the baseline showed stable pathology with no change in size in 13 patients, minimal response in 18 patients, moderate response in 23 patients and significant response in 11 patients.

CONCLUSION

This study on 68 patients with deep-seated pathologies undergoing interstitial photodynamic therapy provided evidence that PDT can be the fourth modality in the management of tissue disease.