Photodynamic therapy of head and neck cancer

Photodynamic therapy of early stage oral cavity and oropharynx neoplasms: an outcome analysis of 170 patients

The indications of photodynamic therapy (PDT) of oral cavity and oropharynx neoplasms are not well defined. The main reason is that the success rates are not well established. The current paper analyzes our institutional experience of early stage oral cavity and oropharynx neoplasms (Tis-T2) to identify the success rates for each subgroup according to T stage, primary or non-primary treatment and subsites. In total, 170 patients with 226 lesions are treated with PDT. From these lesions, 95 are primary neoplasms, 131 were non-primaries (recurrences and multiple primaries). The overall response rate is 90.7% with a complete response rate of 70.8%. Subgroup analysis identified oral tongue, floor of mouth sites with more favorable outcome. PDT has more favorable results with certain subsites and with previously untreated lesions. However, PDT can find its place for treating lesions in previously treated areas with acceptable results.

Long-term outcome of treatment of early carcinoma of the lip with Nd:YAG laser

BACKGROUND

The aim of this study was to assess the efficacy of the Nd:YAG laser for treating stage I squamous cell carcinoma (SCC) of the lip. The retrospective study was performed in a tertiary care referral hospital in northern India.

METHODS

In January 2007 the records of patients treated by Nd:YAG laser ablation of the lip between January 1997 and January 2000 were reviewed. Patients with a minimum follow-up of 5 years were included. The postoperative integrity of facial nerve, cosmetic and functional results, and disease (recurrence)-free survival (DFS) were assessed.

RESULTS

Of the 46 patients included, 42 were disease-free at the end of the first year and 38 after 5 years. Six patients required repeat lasering for a residual or recurrent lesion. Two patients developed regional lymph node metastasis with no infield recurrence and underwent modified radical neck dissection. The 5-year DFS rate was 82.6%. Site of lip involvement (upper or lower), history of tobacco use, or grade of the tumor had no influence on DFS. Cosmetic results were excellent and without any significant complication.

CONCLUSION

Our results support the use of the Nd:YAG laser for treatment of stage I SCC of the lip with minimal morbidity and good DFS.

Laser applications in oral surgery and implant dentistry

Lasers have been used for many years in oral surgery and implant dentistry. In some indications, laser treatment has become state of the art as compared to conventional techniques. This article is a comprehensive review of new laser applications in oral surgery and implant dentistry. One of the most interesting developments over the last years was the introduction of the 9.6-microm CO(2) laser. It has been shown in the recent literature that the use of this new device can preserve tissue with almost no adverse effects at the light microscopic level. In contrast, modifications of approved CO(2) laser therapies of premalignant lesions resulted in higher recurrence rates than the conventional defocused laser technique. However, several studies indicate that other wavelengths such as Nd-YAG (lambda = 1,064 nm) or diode lasers (lambda = 810 nm) may be also of value in this field. In many other indications, the use of lasers is still experimental. Intraoperatively used photodynamic therapy or peri-implant care of ailing implants with the CO(2) laser seems to be more of value than conventional methods. However, further studies are required to assess standard protocols. Over the past years, research identified some new indications for laser treatment in oral surgery and implant dentistry. Moreover, well-known laser applications were defined as state of the art. Nevertheless, further studies are required for laser treatment in oral surgery and implant dentistry.

Experimental evaluation of possible side effects of intra-operative photodynamic therapy on rabbit blood vessels and nerves

BACKGROUND AND OBJECTIVES

Tumours of the head and neck show a high local tumour recurrence rate ranging between 7 and 30% despite combined treatment modalities. To improve these data, photodynamic therapy (PDT) might be used as an additional treatment besides surgery and radio-chemotherapy. Intra-operative PDT has been proposed to "sterilise" the tumour bed after surgical tumour resection in order to kill any remaining tumour cells which are responsible for local tumour recurrences. Often, during head and neck surgery, large blood vessels and important nerve structures are exposed and could potentially be harmed by intra-operative PDT. Despite the fact that mTHPC is the most commonly used photosensitiser for head and neck tumours, there are no data on potential detrimental side effects of intra-operative PDT onto these vital structures. The purpose of this study was to use a maximal treatment protocol in rabbit observing possible damage to the blood vessels and nerve structures and thus judge the most severe event that could happen in patients.

STUDY DESIGN/MATERIALS AND METHODS

In rabbits the large blood vessels and nerve structures at the neck and at the groin area were surgically exposed and treated by mTHPC-mediated intra-operative PDT. Various treatment parameters (drug-light interval, light dosage, follow up interval) were modified in order to find the critical treatment parameters which might cause maximum tissue effects. The intention was to define the most severe clinical complications which could be expected from mTHPC mediated intra-operative PDT.

RESULTS

The most severe tissue reactions were found at a drug dosage of 0.3 mg/kg, a drug-light interval of 24 hours and a light dosage of 20 J/cm(2). Complete necrosis was found for the muscles, fat and connective tissue within the entire treatment field. Blood vessels demonstrated severe oedema, media-hyperplasia or loosening of the endothelial layer leading to various degrees of local thrombosis but no break down of the vessel wall or any rupture was noted. Most nerves were altered by a 75% demyelisation but this did not result in any clinical symptoms.

CONCLUSIONS

Our results have shown that mTHPC mediated intra-operative PDT used with a maximal treatment protocol (very high doses and very short drug-light intervals) has significant histological impact onto all tissue structures, but did not show any clinical symptoms in rabbits. mTHPC mediated intra-operative PDT seems to be a promising and a safe treatment option which could complement existing treatment modalities in order to improve total survival rate of tumour patients.