Photodynamic Therapy: Looking at Treatment of Early-Stage Oral Cancer in a New Light

Gal Shafirstein, DSc
Published: Tuesday, Oct 24, 2017
dan-duncanGal Shafirstein, DSc
 
Member and Professor of Oncology,
Department of Cell Stress Biology
Director, Photodynamic Therapy Clinical Research
Roswell Park Cancer Institute
Buffalo, New York
Strategic Partnership
Although surgery and radiotherapy are standard treatment modalities for grade T1/T2 oral cavity cancer (OCC), both approaches have well-documented limitations, including their association with adverse effects that lower quality of life (QoL) for patients.

Surgery for these tumors often requires removal of functional tissue, which can affect speech and swallowing, and the risk of local recurrence following surgery is as high as 20%.1-3 The adverse events (AEs) associated with radiation therapy, such as xerostomia, chronic dental decay, and risk of mandibular osteonecrosis, remain long after the patient is “cured.”4 The long-term nature of these AEs is of particular significance for younger patients, in whom the incidence of OCC is rising and who may have more at stake in terms of QoL.4,5

For these reasons, it is important to consider alternative frontline therapies with less impact on QoL, such as photodynamic therapy (PDT), which has emerged as an attractive option for treating patients with early-stage OCC.

How PDT Works

Developed at Roswell Park Cancer Institute in the late 1970s, PDT is an FDA-approved treatment for early-stage lung cancer and palliation of late-stage lung cancer. It involves the generation of reactive oxygen species and radicals through light activation of photosensitizers administered intravenously a few hours to 4 days prior to treatment (Figure). PDT can be administered before or after surgery, chemotherapy, or radiation, without lowering the strength of the response to these therapies.6 At Roswell Park, PDT is offered as a treatment option for nonmelanoma skin cancer, lung, and esophageal cancers, as well as Barrett’s esophagus and other precancerous conditions.

Figure. Major Components of the PDT Process6

Major Components of the PDT Process

PDT for Early-Stage Head and Neck Cancer

Numerous studies over the past 25 years have demonstrated the safety and efficacy of PDT in the treatment of early-stage oral and oropharyngeal carcinomas. Between 1990 and 2013, 729 patients were treated with PDT with a cumulative overall tumor response rate of 85%. Patients whose cancer did not fully respond to PDT and who underwent secondary treatment with either surgery or repeated PDT showed 100% complete response. The AEs of PDT are largely limited to photosensitivity and pain at the treatment site, which is easily managed by analgesics. Photosensitivity, which generally manifests as mild to moderate edema, can be limited through patient education and temporary avoidance of prolonged sun exposure.

Importantly, several studies have shown that PDT of OCC results in less treatment-associated morbidity than do conventional therapies, including little to no nerve damage, minimal scarring, and retention of organ function.7-11


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Oncology Best Practice™: Choosing Therapies for Patients with EGFR-Mutant Lung Cancers: More Options... More Decisions... Better OutcomesFeb 28, 20182.0
Clinical Vignette Series: 34th Annual Chemotherapy Foundation Symposium: Innovative Cancer Therapy for Tomorrow®Feb 28, 20182.0
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