Evaluation of long-term outcome and prognostic factors of feline squamous cell carcinomas treated with photodynamic therapy using liposomal phosphorylated meta-tetra(hydroxylphenyl)chlorine.

Abstract

OBJECTIVES:

The aim of this study was to evaluate the efficacy, long-term outcome and prognostic factors of feline squamous cell carcinoma (SCC) treated with photodynamic therapy (PDT).

METHODS:

Cats with histologically verified SCC of the head and neck received an intravenous injection of liposomal phosphorylated meta-tetra(hydroxylphenyl)chlorine (mTHPC) and 4 h later 652 nm light was delivered by a diode laser. One group received ⩽10 J/cm2, the other 20 J/cm2. Tumour response and duration were analysed with stage, tumour diameter, location and treatment intensity as prognostic factors.

RESULTS:

In total, 63 lesions in 38 cats underwent treatment with ⩽10 J/cm2 (n = 22) and 20 J/cm2 (n = 41). Overall response rate was 84% (complete remission 61%, partial remission 22%) with a mean progression-free interval of 35 months (median not reached) and a median overall survival time of 40 months (95% confidence interval 33-47). With regard to tumour stage, invasiveness yielded a highly significant worse outcome ( P <0.017). All patients with invasive tumours showed progression at less than 6 months. Larger lesions were associated with inferior control and treatment intensity, and tumour location did not influence response and duration.

CONCLUSIONS AND RELEVANCE:

PDT using a systemic photosensitiser leads to excellent long-term tumour control in the majority of cats. However, invasive and large tumours had a clearly inferior outcome, even if treated with the higher-dose intensity. This suggests that advanced lesions are not indications for PDT.

• Authors: Irene Flickinger, Eva Gasymova, Simona Dietiker-Moretti, Alexander Tichy, Carla Rohrer Bley
• Journal: Journal of feline medicine and surgery (J Feline Med Surg) Vol. 20 Issue 12 Pg. 1100-1104 (12 2018) ISSN: 1532-2750 [Electronic] England
• PMID: 29359611 (Publication Type: Journal Article)

Chemical References

• Antineoplastic Agents
• Mesoporphyrins
• Photosensitizing Agents
• temoporfin

Topics

• Animals
• Antineoplastic Agents (therapeutic use)
• Carcinoma, Squamous Cell (therapy, veterinary)
• Cat Diseases (drug therapy, therapy)
• Cats
• Female
• Head and Neck Neoplasms (therapy, veterinary)
• Male
• Mesoporphyrins (therapeutic use)
• Photochemotherapy (veterinary)
• Photosensitizing Agents (therapeutic use)
• Prognosis