Abstract
PurposeTo observe the late toxicities in nasopharyngeal carcinoma (NPC) patients who achieved long-term survival after intensity modulated radiation therapy (IMRT).Methods208 untreated NPC patients who received IMRT and survived more than five years with locoregional disease control and no metastasis were evaluated in this study. The prescription dose to the gross target volume of nasopharynx (GTVnx), positive neck lymph nodes (GTVnd), clinical target volume 1 (CTV1) and 2 (CTV2) was 68Gy/30f, 60-66Gy/30f, 60 Gy/30f and 54Gy/30f, respectively. The nasopharynx and upper neck targets were irradiated using IMRT, and the lower neck and supraclavicular fossae targets were irradiated using the half-beam technique with conventional irradiation. The late toxicities were evaluated according to the LENT/SOMA criteria of 1995.ResultsThe median follow-up time was 78 months (60–96 months). The occurrence rates of cervical subcutaneous fibrosis, hearing loss, skin dystrophy, xerostomia, trismus, temporal lobe injury, cranial nerve damage, cataract, and brain stem injury induced by radiotherapy were 89.9%, 67.8%, 47.6%, 40.9%, 7.21%, 4.33%, 2.88%, 1.44%, and 0.48%, respectively. No spinal cord injury and mandible damage were found. Grade 3–4 late injuries were observed as follows: 1 (0.48%) skin dystrophy, 4 (1.92%) cervical subcutaneous fibrosis, 2 (0.96%) hearing loss, 2 (0.96%) cranial nerve palsy, and 1 (0.48%) temporal lobe necrosis. No grade 3–4 late injuries occurred in parotid, temporomandibular joints and eyes. Xerostomia decreased gradually over time and then showed only slight changes after 4 years. The change in the incisor distance stabilised by 1 year after RT, however, the incidence of hearing loss, skin dystrophy, subcutaneous fibrosis and nervous system injuries increased over time after RT.ConclusionThe late injuries in most NPC patients who had long-term survivals after IMRT are alleviated. Within the 5 years of follow-up, we found xerostomia decreased gradually; The change in the incisor distance stabilised by 1 year after RT; while hearing loss, nervous system injuries increased over time after RT.
Highlights
Nasopharyngeal cancer (NPC) is one of the most important head and neck cancers in China
Cui [15] reported that the mean doses of the optical nerves, temporal lobes, Temporomandibular joints (TMJ), and middle ears all were over 63 Gy and that some were even higher than Gy, with a prescription dose of Gy gross target volume of nasopharynx (GTVnx) in conventional Two-dimensional radiation therapy (RT)
The results showed that the maximum excretion rate (MER) of parotids in patients with intensity modulated radiation therapy (IMRT) recovered by more than 25% after 6 months in 64.5% of patients who received a mean dose of 43.9 Gy (33.2–58.8 Gy)
Summary
Nasopharyngeal cancer (NPC) is one of the most important head and neck cancers in China. More than 50% of NPC patients treated with two-dimensional radiation therapy (2-D RT) achieved long-term survival [1]. Late adverse events are obvious in these surviving NPC patients and greatly affect their quality of life [2]. IMRT clearly alleviates acute RT injuries, such as xerostomia, during the middle and later periods of RT [10] and remarkably reduces the degree of late injuries more than six months after RT [6,7,8,9,10,11,12]. Many reports regarding the late injuries of NPC patients after IMRT had short follow-up periods. We observed the long-term late toxicities in NPC patients after IMRT in the present study
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