Ryo Toya MD, Abstract Co-Author: Nothing to Disclose

Ryuji Murakami MD, Presenter: Nothing to Disclose

Toshinori Hirai MD, Abstract Co-Author: Nothing to Disclose

Mika Kitajima MD, Abstract Co-Author: Nothing to Disclose

Yasuyuki Yamashita MD, Abstract Co-Author: Nothing to Disclose

Natsuo Oya, Abstract Co-Author: Nothing to Disclose

Patients receiving external beam radiation therapy (RT) for head-and-neck cancer experience anatomical changes during the course of treatment, which is particularly important in sophisticated RT techniques, notably intensity-modulated radiation therapy (IMRT). We retrospectively evaluated the relationship between the parotid gland volume and saliva production during the course of RT.

We retrospectively evaluated 16 assessable patients with advanced oral cavity cancer. Eligibility criteria were a pathologic diagnosis of squamous cell carcinoma, preoperative RT with a total dose of 30Gy delivered in 15 fractions, and both anatomic assessment with CT or MRI and functional assessment with the Saxon test before and 2 weeks after 30Gy irradiation. For the Saxon test, saliva production was measured by weighing a folded sterile gauze pad before and after chewing; the low-normal value is 2 g/2 min. Anatomic and functional changes were compared with the paired Student t-test, the Pearson correlation coefficient, and the Fisher exact test.

The mean parotid volume was decreased after 30Gy irradiation (67.8 ± 19.2 vs. 47.4 ± 13.7 cm3, p<0.01); the post-RT:pre-RT parotid volume rate ranged from 54 - 85%. Mean saliva production was decreased after 30Gy irradiation (4.3 ± 1.5 vs. 1.1 ± 0.6 g/2 min, p<0.01); the post-RT reduction in saliva production ranged from 1.7 - 5.4 g/2 min. The parotid volume rate was inversely correlated with the saliva-reduction amount (r=-0.748, p<0.01). Of 8 patients with saliva reduction of more than 3 g/2 min, 6 (75%) manifested a post-RT parotid volume less than 70% of the pre-RT volume, this was true in only 1 (13%) of 8 patients whose saliva production was reduced by less than 3 g/2 min (p=0.04).

There was a correlation between decreased parotid gland volume and decreased saliva production during the course of RT.

In patients manifesting a marked decrease in saliva production and changes in the parotid gland volume during RT, the radiation-dose distribution should be re-evaluated.

Toya, R, Murakami, R, Hirai, T, Kitajima, M, Yamashita, Y, Oya, N, Parotid Gland Changes after 30Gy Irradiation in Patients with Oral Cavity Cancer Treated with Preoperative Conventional Radiation Therapy.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5015480.html