Thyroid function post supraclavicular lymph node irradiation in patients with breast cancer

Abstract

ABSTRACT

Background Breast cancer remains the most common cancer in women worldwide and across Africa in particular. In East Africa, the estimated incidence of breast cancer comes second only to cervical cancer. Supraclavicular irradiation post modified mastectomy is a crucial component of breast cancer management; it improves local control and overall survival. This is however associated with adverse effects including thyroid dysfunction which is usually under-reported.

Aim To evaluate radiation induced thyroid gland functional changes following treatment of supraclavicular lymph nodes in breast cancer patients.

Methods This was a prospective descriptive study of patients with breast cancer who were recruited from May 1, 2017 and subsequently followed up until May 30, 2018 at ORCI. Descriptive statistics were used to report patient demographics, disease characteristics. Pretreatment TSH, fT4 and fT3 values were compared with the corresponding values obtained after treatment by Wilcoxon signed-rank test. Results A total of 42 patients were recruited for this study with a mean age of 55.7 (32-71) years. The mean for baseline TSH level was 2.90(±6.37) while that for T4 and T3 were 15.77(±4.83) and 3.46(±6.22) respectively. A Wilcoxon signed-rank test indicated that there was a statistically significant rise in mean TSH level at baseline compared to those at 3, 6 and 9 months post treatment with p-values of 0.0047, 0.0002 and less than 0.0001 respectively. The difference between baseline mean levels for T3 and T4 was statistically significant both at month 6(T3, p=0.0028; T4, p=0.0018 and month 9(T3, p=0.009; T4, p=0.0001) of follow up respectively. Subclinical HT was found in 10% of the patients. Conclusion As it was hypothesized, there was a trend towards subclinical HT and these results reflect the necessity to routinely evaluate thyroid function in patients treated with radiation to the supraclavicular region.