Incidence of Hypothyroidism in Patients Treated With Radiation Therapy for Head and Neck Tumors in Kenyatta National Hospital

Abstract

BACKGROUND Head and neck (H&N) malignancies encompass a broad number of sub-sites and are commonly treated with surgery and radiation. Chemotherapy may also be incorporated in the treatment of this malignancies in some of the cases. There are numerous side effects following treatment with ionizing radiation. Some are acute while others tend to occur over longer periods of time (chronic). Radiation induced hypothyroidism is an overlooked area in oncology care. With symptoms being mistaken for co morbidities or for symptoms that are treatment related. BROAD OBJECTIVE The purpose of this study was to investigate the incidence of radiation induced hypothyroidism among patients who undergo radiation therapy as part of their treatment for histologically confirmed H&N cancers. STUDY SETTING The study took place at the Kenyatta National Hospital’s cancer treatment centre, where most patients with confirmed malignancies of the H&N region are reviewed and the planning for treatment done. STUDY POPULATION The study set out inclusion and exclusion criteria: Patients who were recruited into the study had histologically confirmed H&N cancer and received adjuvant or definitive radiation treatment. Their performance status was ECOG ≤2, and ages were between 15 and 84 years. Patients with stage I, II, III and IVA were included in the study. The study excluded patients who already had a confirmed diagnosis of thyroid cancer. It also excluded patients with a prior history of total or partial thyroidectomy, and who were on follow up for thyroid diseases: Graves’ disease, autoimmune thyroiditis etc. Another subset of patients who were excluded from the study were patients who prior to commencing treatment, had sub clinical hypothyroidism or primary hypothyroidism. Patients with metastatic disease at diagnosis were also excluded from the study. STUDY DESIGN AND METHODOLOGY The proposal was for a prospective single arm cohort study to identify the incidence of hypothyroidism in patients treated for H&N malignancies with radiation therapy. The data was collected using various interview schedules: These schedules gave information on the patient demographics, past history of surgery, radiation treatment techniques and duration, value of thyroid function tests at different periods and clinical symptom assessment...