PDT Cancer Case Study #1: Invasive Squamous Cell Carcinoma Cured In 6 Weeks

This is a case study by Dr. Merrill Biel of a 69 year old male presenting with a history of right mouth soreness for the past six months. This patient has no history of sore throat, dysphagia, hemoptysis or shortness of breath. He is a smoker (2 ppd for the past 50 years) and drinks two alcoholic beverages per day.

During his mouth examination, irregular cobblestoned mucosa of the entire right floor of the mouth was found (Figure 1). There were three areas each 1 cm in diameter of invasive firm nodules. Biopsies were then obtained and it was determined that the patient had invasive squamous cell carcinoma.  He was staged as a T3N0 superficial squamous cell cancer of the right floor of mouth and ventral tongue.

Left (Figure 1): Patient presents with squamous cell cancer of entire right floor of mouth and ventral tongue. Right (Figure 2): Six weeks post- PDT Treatment, area of tumor healed with normal mobile mucosa and without scar tissue

The patient’s cancer could be treated with a number of modalities including surgery or radiotherapy. Surgical resection would provide for a good cure rate but would likely leave the patient an oral cripple. Radiotherapy as well would have an excellent cure rate but the patient would have long-term xerostomia (dry mouth), which can cause difficulty in speech and eating. Photodynamic therapy is a minimally invasive outpatient treatment that has been found in Phase II clinical trials to provide at least the same cure rates as surgical or radiotherapy for superficial oral carcinomas.  As all of these treatment options provide for the same cure rates, it was important to discuss the various treatment options with the patient including each treatment’s risks and benefits. This way the patient could decide which treatment they would prefer to undergo for their cancer therapy.  Importantly, PDT treatment does not eliminate the options for other therapies should there be a recurrence of disease. This patient chose to undergo photodynamic therapy treatment.

Photodynamic therapy works by applying a photosensitizing agent to the affected site and activating it with a laser light. Photofrin was injected intravenously at a dose of 2.0 mg/kg over a 5 minute period as an outpatient procedure.  Approximately 48 hours after the injection, the patient underwent general anesthesia and intubation. The tumor of the right floor of mouth, mandible and ventral tongue was measured using a small ruler. The area to be treated included the actual tumor and at least 5mm of normal appearing tissue.  In this case, the area to be treated was measured to be 6×4 cm. Normal tissue of the tongue and cheeks and left floor of the mouth were protected from light administration using moist surgical gauze sponges.

Using a Nd:Yag pumped-dye laser (Laserscope) at 630 nm wavelength, light was delivered to the tissue bed.  The light treatment was performed at 75 J/cm2 and 150 mW/cm2. Light was delivered for a period of 500 seconds. In addition, the three areas of tumor invasion were treated.  This light treatment was performed at 100 J/cm fiber length at a fluence rate of 400mW per cm fiber length.

On completion of treatment, the patient received Decadron (an anti-inflammatory medication) intravenously to reduce tissue edema. With PhotofrinR PDT, when normal tissue is exposed to the 630 nm light, the limited amount of PhotofrinR in the normal tissues will be activated resulting in tissue edema. This reaction occurs immediately so that by the end of the light illumination the tissue edema is maximal.  Therefore, the patient was observed in the recovery room for 2 hours post treatment in order to ensure that the airway was stable.   After two hours of airway observation, with a normal airway, the patient was discharged to home with oral pain medications.  He was instructed to avoid daylight outside for 30 days, standard room light exposure causes no problems. He was instructed to proceed with a normal diet as tolerated and there are no voice use restrictions.

Tumor response was evaluated at 1 week, 1 month and then every 3 months thereafter.  At one week, the selective tumor necrosis is noted.  Multiple biopsy specimens of the treated area were obtained 6 weeks after treatment that demonstrated a complete histopathologic response (Figure 2).  Remarkably, the area of tumor resolution healed in with normal mobile mucosa without scar tissue.  As well, the submandibular ducts remained patent and fully functional.  The only area of scar was where the invasive tumor nodules had destroyed the collagen matrix of the tissue.  This patient has remained free of disease for over 5 years.

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