Effect of Thyroid-Related Symptoms on Long-Term Quality of Life in Patients with Differentiated Thyroid Carcinoma: A Population-Based Study in Sweden.

Background: Differentiated thyroid cancer (DTC) has a good prognosis but a remaining risk of recurrence, and life-long follow-up as well as medication with levothyroxine may be necessary. The aim of this study was to clarify how thyroid-related symptoms affect health-related quality of life (HRQoL) 14-17 years after diagnosis in Swedish DTC patients.

Methods: From the all-encompassing population-based Swedish Cancer Registry, 353 patients diagnosed with DTC during 1995-1998 were identified and invited to answer a study-specific questionnaire and the HRQoL questionnaire SF-36 14-17 years after their diagnosis. Subgroups were studied according to thyroid-related symptoms, both symptoms correlated to thyroid disease or levothyroxine treatment and side effects from surgery and radioiodine treatment.

Results: Of the patients with DTC, 279 (79%) answered the questionnaires. In all, only 19 (7%) reported a recurrence. Patients with one single symptom (e.g., fatigue, sleeping disorders, irritability, lower stress resistance, muscle weakness, bodily restlessness, sweating, palpitations, or flushes) had significantly lower HRQoL measured with the SF-36 compared to those without that specific symptom (p < 0.001). Furthermore, those 238 patients with at least one symptom, regardless of which one, had significantly lower HRQoL in all eight SF-36 domains compared to patients that no thyroid symptom (n = 34; p < 0.001). In seven patients, the questionnaires were not complete in terms of the thyroid-related questions. The association between thyroid symptoms and lower HRQoL remained after adjusting for age, sex, comorbidities, education, and menopause.

Conclusions: DTC patients reporting thyroid symptoms scored lower in HRQoL compared to those with no symptoms >14 years after diagnosis.