Thyroid Cancer Outcomes Worse with Previous Radiation Exposure

Last Updated: 2009-04-29 13:43:13 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Thyroid cancer patients with a history of radiation exposure have more aggressive disease and worse clinical outcomes than patients without previous radiation exposure, according to findings published in the April issue of the Archives of Otolaryngology--Head and Neck Surgery.

Dr. Jeremy L. Freeman and colleagues from Mount Sinai Hospital, Toronto, Ontario, Canada, conducted a retrospective chart review of 125 patients (95 women, 30 men) diagnosed with thyroid cancer who had a history of radiation exposure prior to surgical treatment.

Inclusion criteria included a history of radiation exposure at least 3 years before diagnosis of thyroid cancer. Type of exposure included radiotherapy, radioactive iodine treatment, and occupational, diagnostic or environmental exposure.

The mean age of the patients was 48.2 years and the mean age at first exposure to radiation was 19.4 years. Pathological results showed that 89% of patients had papillary thyroid carcinoma.

The patients were followed up for a mean of 10.6 years. "Sixteen percent of patients had local recurrence of disease, and 9% had distant metastases," Dr. Freeman and colleagues report. "

The investigators compared this patient cohort with a group of 574 general thyroid carcinoma patients. They found that the radiation-exposed patients were more likely to undergo total or near-total thyroidectomy (83% versus 38%), to require multiple operative procedures (23% versus 2%), and to require adjuvant external radiotherapy (6% versus 1%) compared to the general thyroid cancer patients.

Patients who had previous radiation exposure were more likely than the general thyroid cancer group to have multifocal tumors (63% versus 36%), extrathyroid extension (26% versus 8%), stage IV disease (16% versus 5%), and distant metastases (9% versus 2%).

Eight percent of radiation-exposed patients had disease at follow-up, compared with 3% of the general thyroid cancer group. Radiation-exposed patients were more likely to have died of thyroid disease at follow-up (4% versus 1.5%).

The team concludes that, while most patients with well-differentiated thyroid cancer can expect good outcomes, the current findings suggest that patients who have been exposed to radiation "may require more aggressive treatment."

Arch Otolaryngol Head Neck Surg 2009;135:355-359.


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