Radiotherapeutic management of locally advanced head and neck cancer

Abstract

Head and neck cancer management has undergone several paradigm shifts for several relevant reasons. From the dismal experience with the use of radiotherapy as the sole modality in the treatment of this group of patients with advanced disease, radiotherapy has been evaluated as an adjuvant for the same group of patients who had undergone successful surgery. Although there is no level 1 evidence to support postoperative adjuvant radiation, several studies have demonstrated that adjuvant radiotherapy reduces the local failures and, thereby, improves survival. Predictors of recurrence after surgical resection are: positive margins of resection; extranodal spread in involved nodes; perineural invasion; and presence of two or more involved regional lymph nodes. Realization of the advantages of a combination of chemotherapy with radiotherapy has had a major impact on the management of these cancers. There is emerging evidence for the use of adjuvant concurrent chemoradiotherapy in the group with high-risk features. Multiple organ conservation strategies in the management of locally advanced head and neck cancers have evolved over the years. However, the meta-analyses of impact of chemotherapy in various settings reveal that concomitant chemoradiotherapy is superior to any of the other regimens. Increasing use of computed tomography, magnetic resonance imaging and positron emission tomography scan images has resulted in better visualization of target volumes and critical structures. Delineation of these structures is of paramount importance and has resulted in a profound change in conformal treatment planning. Better understanding of the physical aspects of delivery of radiotherapy and the advent of modern treatment planning systems have led to the development of conformal techniques. Although the benefit of these techniques on survival have yet to be demonstrated, there is evidence to suggest that they reduce treatment-related toxicities significantly and facilitate dose escalation. Increased knowledge of radiobiology has led to the development of various altered fractionation regimens in the management of locally advanced head and neck cancers. Discovery of cell-cycle kinetics and signal transduction pathways has led to the unearthing of several potential targets for targeted therapy. The epidermal growth factor recepter gene has emerged as the most promising target. The role of biological radiation response modifiers is evolving. All of these approaches to improve the therapeutic gain would be incomplete without evaluating their effect on the quality of life of these patients.

Keywords::

• head and neck cancer
• locally advanced
• radiotherapy