High-Precision Radiation Therapy

Intensity modulated radiation therapy (IMRT) is particularly interesting for the treatment of HNSCC because of its ability to reduce radiation doses to the many critical normal tissues that surround tumors, thereby dimishing morbidity. The efficacy of IMRT in sparing parotid glands, thereby diminishing the severity of radiation-induced permanent xerostomia in selected patients, has been amply demonstrated during the past decade.  

 

The advances made in laboratory research and clinical trials on head and neck cancer during the past 2 decades have been exciting and gratifying. Progress in molecular biology techniques has opened research avenues yielding new knowledge about the molecular basis of cellular behavior and mechanisms governing radiation response. Some of this wisdom has already found application in the development of novel therapy strategies that are being tested. The basic and translational research efforts have finally paid off in that the mortality rates for head and neck cancers in the United States have declined since the inception of record keeping. For example, the annual death rate among men from oral cavity and pharyngeal cancers in the United States decreased by an average of 1.9% from 1975 to 1993 and by 3% from 1993 to 2001.38Clinical research on altered fractionation schedules and various combinations of radiation therapy with chemotherapy has generated firm data leading to changes in the standard of care for patients with intermediate-stage and locally advanced carcinoma of the oral cavity, oropharynx, larynx or hypopharynx, and nasopharynx. The concept of combining radiation therapy with molecular therapeutics has been validated, and the first generation of such therapy, radiation plus cetuximab, has become an option for day-to-day practice. The expertise in the application of IMRT for the treatment of some subsets of patients with HNSCC and in quality assurance and procedural improvements is improving, and proper indications for and the value of IMRT for combined-modality therapy are being assessed.The pace of discovery is anticipated to increase in the coming years. For example, it is reasonable to envision that new approaches for characterizing the molecular profile of various types of cancer will depict their individual virulence, predict their response to therapy, and guide the selection of treatment. The outlook for developing rational therapy strategies aimed at specific molecular targets to prevent malignant transformation or reverse a malignant phenotype is also increasingly optimistic. The insights and new technologies gained from further research should have considerable impact on reducing the mortality rates for head and neck cancers.The fast pace of new discoveries and the large number of research directions make determining what constitutes “standard therapy” for a variety of patient subsets increasingly complex. When several treatment options can yield approximately the same locoregional tumor control rate, other determinants need to be taken into account in selecting the best treatment for individual patients. These determinants include the cosmetic and functional outcomes acute and long-term morbidity (i.e., quality of life), resource use (i.e., cost), physician expertise, and patient convenience.