Medicina Nuclear e Radioterapia

Radiation Induced Hypothyroidism and its Relationship with Gender and Smoking History in Head and Neck Cancer Patients

Abstract

Tariq Khurram, Rana Fauzia, Zuberi Lara, Zaiden Robert, Farhangi Arezo, Ibrahim Saif, Tariq Wajiha, Palacio Carlos, Al-Saffar Farah and Pham Dat

ntroduction: Patients with head and neck cancers are often treated with external beam radiation therapy. Unfortunately this therapy is not without its unintended consequences. One of these side effects include the development of radiation induced hypothyroidism. Our study is designed to pay special attention to variables like gender and smoking history and analyze their relationship with the development of hypothyroidism. Methods: Tumor Registry Database at the University of Florida, College of Medicine in Jacksonville was utilized for our retrospective study to gather information on patients who had previously received external beam radiations for head and neck cancers. Patients’ charts were reviewed over a period of thirteen years from January 1st 2000 to November 30th 2013. General characteristics were examined including age, gender, race/ethnicity, and smoking history. Hypothyroidism was defined as TSH value greater than 5.0 along with appropriate decrease in free serum thyroxine (T4) levels after exposure to external beam radiation. Results were then analyzed using the Univariate statistical analysis which was done using the SAS software. Alpha level of significance was set to 0.05 and associations were expressed in terms of Odds ratio (OR) with 95% confidence intervals (CI). Results: We found a total of 1116 patients in our database who have received external beam radiations for head and neck cancers. Out of these 72 (6.45%) patient developed hypothyroidism. Out of 263 African American patients 20 (7.6%) had hypothyroidism, whereas 49 (6%) out of 819 white people had this outcome. As for gender 32 out of 341 females (9.4%) and 40 out of 775 males had hypothyroidism. Thirty five out of 544 (6.4%) with no family history and 19 (2.4%) out of 205 (9.3%) with positive family history for cancer had the outcome too. Finally 43(6.5%) out of 664 smokers and 17(8.3%) out of 206 non-smokers were found to develop hypothyroid as well. Both groups were found to have homogenous average age at diagnosis. When conducting the univariate analysis, the strongest predicting variable was gender as hypothyroid patients were 1.90 (95% CI 1.17 – 3.09) times more likely to be females, and these results were statistically significant with p-value of 0.008. More patients tended to be African Americans with OR 1.21 (CI 0.822 - 1.78), had positive family history of cancer, (negative family history had OR 0.67 (CI 0.38 – 1.21), and less likely to be smokers (OR 0.77 (0.43 – 1.38). However, Race, family history of cancer and smoking history did not achieve any statistical significance as evident by the p-values. Conclusion: In our patient population, females were more likely to develop radiation induced hypothyroidism.