The treatment strategies for oral cancer have been improving and have reduced postoperative mortality and increased the survival rate of oral cancer patients. Many issues around the major functional loss arising after treatment have been improved by microsurgical reconstructive techniques. However, surgery and chemoradiotherapy for advanced oral cancer often cause severe disabilities, such as disfigurement and problems with chewing, speech and swallowing. The impact of oral cancer resection and reconstruction on swallowing functions has been evaluated in several studies. Various risk factors of postoperative dysphagia have been identified, including poor performance status, the location of resection, anterior or extensive mandibular bone resection, method of reconstruction, tongue mobility and volume, and postoperative radiotherapy. Posttreatment function and quality of life (QOL) is influenced by various factors such as T stage, N stage and neck dissection. The deterioration of QOL by decreased postoperative function can lead to socio-economic failure, depression and, eventually, suicide.
Numerous subjective and objective evaluation of swallowing ability measures are available. The major objective evaluation for swallowing ability is videofluoroscopic evaluation (VE). Clinical evaluations are widely performed by various functional tests. These tests that conduct subjective evaluation include grading systems such as the Swallowing Ability Scale System (SASS), the M.D. Anderson Dysphagia Inventory, the Performance Status Scale for Head and Neck Cancer patients (PSS-H&N), and the Functional Assessment of Cancer Therapy-H&N (FACT-H&N). However, some scales involved multiple questionnaire and can be too difficult to understand for older patients. Fujimoto et al. reported the SASS using the MTF score that can easily evaluate swallowing function. The SASS is useful for bedside evaluation because the test is simple and easy and can evaluate by referring to actual feeding condition.