Photodynamic therapy for treatment of cancers in oral and maxillofacial regions: a long-term follow-up study in 72 complete remission cases

Effectiveness of photodynamic therapy on treatment response and survival in patients with recurrent oral squamous cell carcinoma: A systematic review

BACKGROUND

This systematic review assessed the effectiveness of photodynamic therapy (PDT) in patients with recurrent oral squamous cell carcinoma (OSCC).

METHODS

Clinical studies on recurrent OSCC treated with PDT alone were included. Combined treatment strategies were excluded. The search was performed on Medline/Pubmed, Cochrane Library, Embase, Web of Science and ClinicalTrials.gov, manual search, and grey literature.

RESULTS

The eleven included studies were observational. The risk of bias and methodological quality were evaluated using the Newcastle-Ottawa Quality Assessment Scale. The studies reported the use of hematoporphyrin derivative, PhotofrinⓇ, FoscanⓇ and 5-aminolevulinic acid. Data on treatment response and survival was collected. Secondarily, postoperative courses and patient's quality of life/acceptance were reported whenever available. PhotofrinⓇ and FoscanⓇ were the most used photosensitisers, with more complete responses. Lesions responding less favourably were on posterior regions or deep-seated in the tissue.

CONCLUSIONS

Although treatment response differs between treatment protocols, PDT stands as a viable treatment option to be considered, as it can achieve therapeutic results and disease-free, long-lasting periods. Partial treatment responses may be of interest when achieving eligibility for other treatment strategies. Despite this study's limitations, which considered four photosensitisers, PhotofrinⓇ was the most used but more recent photosensitisers like FoscanⓇ have greater chemical stability, tissue penetration, and may be more efficacious on recurrent OSCC.

mTHPC-mediated photodynamic therapy for early oral squamous cell carcinoma

Surgery and radiotherapy are standard treatments for early oral squamous cell carcinoma, both resulting in good tumour control. However, neither of these modalities is without consequent functional or cosmetic impairment, and there are patients in whom both are contraindicated. Furthermore, there is a significant risk of metachronous tumours developing in the oral cavity, and salvage or retreatment with either surgery or radiotherapy poses difficulties. Photodynamic therapy (PDT) offers the potential for improved functional and cosmetic outcomes, while achieving comparable tumour control. We conducted an open-label, multicentre study to assess the efficacy and safety of meta-tetrahydroxyphenylchlorin (mTHPC) in patients with early oral cancer. One hundred twenty-one patients received intravenously administered mTHPC, followed 96 hr later by illumination of the tumour surface with 652 nm laser light. Of these patients, 114 were protocol compliant. A complete tumour response was achieved in 85% of protocol-compliant patients (97 of 114 patients). A complete response was maintained in 85% of responders at 1 year and in 77% at 2 years. One- and 2-year actuarial survival rates were 89% and 75%, respectively. In the opinion of the investigators, tumour clearance was accompanied by excellent cosmetic and functional results, without impact on the patients' performance status. Mild-to-moderate pain at the treatment site, a recognised side effect of PDT in the oral cavity, was reported by 82% of patients but was manageable with appropriate analgesia. Mild-to-moderate skin photosensitivity reactions were reported for 13% of patients. mTHPC offers an effective alternative treatment for early oral squamous cell carcinoma. It is associated with excellent functional and cosmetic results and can be used in conjunction with other standard therapies.

Treatment of squamous cell carcinoma of the lip using Foscan-mediated photodynamic therapy

Carcinoma of the lip is a common cancer of the head and neck area; its incidence is approximately one-quarter that for oral cavity cancers. It occurs most frequently on the lower lip of elderly males. This non-randomized Phase II study aimed to estimate the complete response (CR) rate to Foscan-mediated photodynamic therapy (Foscan-PDT) in patients with primary cancer of the lip, duration of CR, and the tolerability and safety of Foscan-PDT. Twenty-five patients with squamous cell carcinoma (SCC) of the lip (Tis, T1, T2/N0/M0) and Karnofsky status > or = 70 received 0.15 mg/kg Foscan intravenously, followed 4 days later by a single non-thermal illumination of the tumour (light dose 20 J/cm2, irradiance 100 mW/cm2, lambda=652 nm). Response was determined after 12 weeks and mean follow up is 424 days so far. After 12 weeks, 96% of cases (24/25) showed CR, and all CRs were confirmed by biopsy. The most common adverse event was swelling and local pain at the treatment site. Tumour recurrence was observed in two patients 4 and 18 months after PDT. One patient developed a single lymph node metastasis 7 months after therapy. Photosensitivity reactions occurred in five patients. The functional results were excellent in all patients without any signs of limited mouth opening or impaired lip closure. The cosmetic outcome was better than after surgical therapy. Foscan-PDT is an effective treatment modality for small primary tumours of the lips. Foscan-PDT yields complete response rates comparable to those published for surgery or radiotherapy without causing major toxicity. It allows preservation of form and function and does not compromise future treatment options for recurrent, residual or second primary disease.

Photodynamic therapy: an effective, but non-selective treatment for superficial cancers of the oral cavity

It has often been claimed that photodynamic therapy (PDT) produces selective destruction of small cancers without affecting the adjacent normal tissue. The objective of our work was to treat small cancers of the oral cavity with PDT and subsequently excise the treated areas for histological studies of tumour and adjacent normal tissue exposed to the same light dose. Eleven patients with histologically proven T1NO oral squamous-cell carcinomas were treated with PDT, using Photofrin as a sensitiser. The tumours plus a surrounding cuff of normal tissue were exposed to 50 J/cm2 non-thermal laser light at 630 nm delivered by surface illumination and the treated areas subsequently excised. Histological staining and image analysis were used to determine the nature and extent of injury. No macroscopic distinction was evident between tumour and normal tissue exposed to light. Histologically, replacement of superficial epithelium, tumour and connective tissue with a fibrinous necrotic slough was seen. There was also loss of endothelium from small vessels, with haemorrhage and thrombosis. Preservation of subepithelial collagen and elastin was demonstrated with EVG staining. No evidence of selective tumour necrosis was found. Although depth of injury was variable, full thickness mucosal necrosis occurred in all cases.

The efficacy of an iron chelator (CP94) in increasing cellular protoporphyrin IX following intravesical 5-aminolaevulinic acid administration: an in vivo study

5-Aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) is proving to be a useful photosensitizer for photodynamic therapy (PDT). Conversion of PpIX to haem requires catalysed chelation with iron, and thus the presence of an iron chelator should, in theory, lead to an increase in cellular PpIX accumulation. This paper assesses the in vivo effect of a new iron chelator, 1,2-diethyl-3-hydroxypyridin-4-one (CP94), on the kinetics of PpIX in different layers of the bladder wall. Wistar rats were given 1% or 10% ALA intravesically with or without intraperitoneal CP94. The biodistribution of ALA-induced PpIX in the bladder was evaluated using fluorescence microscopy. Photodynamic effects on the bladder were compared in rats receiving various drug dosimetries. In CP94-treated rats, 5-7 h after administration of 10% ALA solution, the fluorescence intensity of PpIX in the urothelium was doubled compared with animals given ALA alone, whereas in the muscle layer PpIX remained at a low level similar to that found without the iron chelator. At an ALA concentration of 1%, although the PpIX concentration was not increased with CP94, the urothelial selectivity of PDT compared with the muscle layer was enhanced. In conclusion, by using CP94, a further reduction in skin photosensitization may be possible as similar photodynamic effects can be achieved with a lower dose of ALA. The addition of CP94 seems to be an effective and convenient way to potentiate ALA-induced PpIX tissue selectivity between the urothelium and the underlying layers of the bladder wall.

Interstitial and transurethral photodynamic therapy of the canine prostate using meso-tetra-(m-hydroxyphenyl) chlorin

Photodynamic therapy (PDT) produces localised necrosis with light after prior administration of a photosensitising drug. Although the technique is promising for small tumours of hollow organs, little work has been done on solid organs like the prostate. We studied the tissue biodistribution and photodynamic effects of meso-tetra-(m-hydroxyphenyl) chlorin (mTHPC), a potent second-generation photosensitiser, on normal canine prostate in vivo. Using quantitative fluorescence microscopy, the highest concentration of mTHPC in the prostate was seen 24-72 hr after intravenous administration. For PDT, red light (650 nm) was delivered to the prostate by laser fibres inserted via the transurethral or transperineal route under transrectal ultrasound guidance. PDT lesions up to 40 mm in diameter (using 4 fibre sites) were produced, characterised by swelling, inflammatory response and extensive glandular destruction. There was persistent glandular atrophy at 90 days, but no disruption of the main stroma and no change in the ultimate size or shape of the gland. Urethral damage sometimes caused temporary urinary retention, but this resolved by 7 days, and no animal became incontinent. Occasional small lesions were seen in the rectum, but these healed without sequelae and there were no fistulae. Since cancer and normal prostate are likely to respond similarly, PDT has considerable promise for treating cancer confined to the gland as large areas of glandular tissue can be necrosed with safe healing. Because the structural integrity of the gland is maintained, PDT is unlikely to be of value in the management of benign prostatic hypertrophy.

Photodynamic therapy of oral cancer. A review of basic mechanisms and clinical applications

Photodynamic therapy (PDT) is an experimental cancer treatment modality. PDT is based on the accumulation of a photosensitive dye in premalignant and malignant lesions. A certain period of time after the dye has been administered, tumor tissue may contain more of the sensitizer then the surrounding normal tissues. When tissue containing the sensitizer is exposed to light of a proper wavelength and dose, a photochemical reaction between sensitizer and light will occur. The activated photosensitizer reacts with available oxygen which subsequently damages cells and eventually may cause necrosis of the tumor. Photosensitizers can also be used for fluorescence detection. If a tumor contains more of the photosensitizer than the surrounding normal tissue, its fluorescence can potentially be utilized to detect tumors. Analogous to PDT, this can therefore be referred to as photodynamic detection (PDD). This paper reviews the basic mechanisms and clinical applications of PDT and PDD. Emphasis is placed on PDD and PDT with the photosensitizer Photofrin for detection and treatment of premalignant epithelial lesions and squamous cell carcinomas of the oral mucosa.