Intensity modulated radiotherapy (IMRT) is a conformal
radiotherapy that produces concave and irregular target
volume dose distributions. IMRT has a potential to reduce
the volume of healthy tissue irradiated to a high dose, but
this often at the price of an increased volume of normal
tissue irradiated to a low dose. Clinical benefits of IMRT are
expected to be most pronounced at the body sites where
sensitive normal tissues surround or are located next to a target
with a complex 3D shape. The irradiation doses needed for
tumor control are often markedly higher than the tolerance
of the radiation sensitive structures such as the spinal cord,
the optic nerves, the eyes, or the salivary glands in the
treatment of head and neck cancer. Parotid gland salivary flow
is markedly reduced following a cumulative dose of 30 50 Gy
given with conventional fractionation and xerostomia may be
prevented in most patients using a conformal parotid-sparing
radiotherapy technique. However, in cohort studies where IMRT
was compared with conventional and conformal radiotherapy
techniques in the treatment of laryngeal or oropharyngeal
carcinoma, the dosimetric advantage of IMRT translated into
a reduction of late salivary toxicity with no apparent adverse
impact on the tumor control. IMRT might reduce the radiation
dose to the major salivary glands and the risk of permanent
xerostomia without compromizing the likelihood for cure.
Alternatively, IMRT might allow the target dose escalation at
a given level of normal tissue damage. We describe here the
clinical results on postirradiation salivary gland function in head
and neck cancer patients treated with IMRT, and the technical
aspects of IMRT applied. The results suggest that the major
salivary gland function can be maintained with IMRT without
a need to compromise the clinical target volume dose, or the
locoregional control.