Patterns of failure in anaplastic and differentiated thyroid carcinoma treated with intensity-modulated radiotherapy

H. Vulpe, J.Y.Y. Kwan, A. McNiven, J.D. Brierley, R. Tsang, B. Chan, D.P. Goldstein, L.W. Le, A. Hope, M. Giuliani

Abstract


Background

The radiotherapy (rt) volumes in anaplastic (atc) and differentiated thyroid carcinoma (dtc) are controversial.

Methods

We retrospectively examined the patterns of failure after postoperative intensity-modulated rt for atc and dtc. Computed tomography images were rigidly registered with the original rt plans. Recurrences were considered in-field if more than 95% of the recurrence volume received 95% of the prescribed dose, out-of-field if less than 20% received 95% of the dose, and marginal otherwise.

Results

Of 30 dtc patients, 4 developed regional recurrence: 1 being in-field (level iii), and 3 being out-of-field (all level ii). Of 5 atc patients, all 5 recurred at 7 sites: 2 recurrences being local, and 5 being regional [2 marginal (intramuscular to the digastric and sternocleidomastoid), 3 out-of-field (retropharyngeal, soft tissues near the manubrium, and lateral to the sternocleidomastoid)].

Conclusions

In dtc, locoregional recurrence is unusual after rt. Out-of-field dtc recurrences infrequently occurred in level ii. Enlarged treatment volumes to level ii must be balanced against a potentially greater risk of toxicity.


Keywords


Thyroid neoplasms; recurrence; radiotherapy; anaplastic thyroid carcinoma; papillary carcinoma

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DOI: http://dx.doi.org/10.3747/co.24.3551






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ISSN: 1198-0052 (Print) ISSN: 1718-7729 (Online)