Adaptive Radiotherapy in Head and Neck Cancers-A Prospective Study

Head and neck cancers (HNC) constitute one of the most common cancers in the developing world. In a recent study from India, of approximately 556,400 cancer deaths in the year 2010, the most fatal cancers were HNC. Radiotherapy plays a central role in treatment of locally advanced head and neck cancers (LAHNC). Over the years, the delivery of radiation therapy has improved with innovations that have reduced toxicity without compromis­ing loco-regional control. Among these advances, the development of intensity-modulated radiation therapy (IMRT) has represented a major turning point in the treatment of HNC patients.

Several factors may result in set-up uncertainties and a potentially decreased therapeutic ratio such as patient repositioning on the treatment table, weight loss, tumor and lymph node shrinkage, tissue swelling and lymphedema, and alteration of fat distribution.   More recently, image guidance has been used for adaptive radiotherapy (ART) — the adjustment of treatment planning dur­ing the course of radiation to account for anatomic changes and improves the thera­peutic index.

Why is ART necessary?

In literature, some studies have reported volumetric changes during adaptive planning. Barker et al  have reported a median GTV reduction at a rate of 0.2 cm3 per day, corresponding to a 70% reduction on the last day of RT.

ART is conceptually an attractive approach to account for and correct tumour and normal tissue variations during treatment, but at present, there are limited data to guide its clinical application in day-to-day practice. This study will help in designing institutional protocol and will give useful scientific data for further studies.