Radiation therapy for glottic cancer using 6-MV photons

Area of Science:

• Radiation Oncology
• Head and Neck Cancer Treatment
• Medical Physics

Background:

• Conventional recommendations for glottic cancer radiation therapy include cobalt-60 or 4-MV photons.
• Higher energy photons (6 MV) may risk underdosing, especially with anterior commissure involvement.
• This study investigates the use of 6-MV photons for glottic cancer treatment.

Purpose of the Study:

• To evaluate the efficacy and safety of using 6-MV photons for glottic cancer radiation therapy.
• To compare treatment outcomes with historical data using cobalt-60 or 4-MV photons.

Main Methods:

• Retrospective review of 73 patients with Tis-T3 glottic tumors treated with curative intent radiation therapy (1975-1991).
• 30 patients received cobalt-60 or 4-MV photons; 43 patients received 6-MV photons.
• Analysis focused on treatment failure patterns, cancer deaths, and local tumor control in the 6-MV photon group, with a minimum two-year follow-up.

Main Results:

• The 2-year initial local tumor control rate was 94.8% for patients treated with 6-MV photons.
• Treatment failures included local recurrence (1), local recurrence with distant metastasis (1), delayed neck metastasis (2), and delayed neck metastasis with distant metastasis (1).
• Salvage treatment was successful in three patients with treatment failure; two patients died from metastases.

Conclusions:

• Glottic cancer can be effectively treated using 6-MV photon radiation therapy.
• Local tumor control achieved with 6-MV photons is comparable to that of cobalt-60 or 4-MV photons.
• 6-MV photons represent a viable and successful treatment modality for glottic cancer.