The influence of lymphangiography on the development of hypothyroidism in patients irradiated for Hodgkin's disease

Abstract

Purpose : There is no consensus in the literature regarding the role of lymphangiography in promoting hypothyroidism in individuals with Hodgkin's disease irradiated with a mantle field. We sought to analyze the onset and rate of developing clinical or chemical hypothyroidism as well as possible factors related to its development in patients who received irradiation to the thyroid gland during treatment of Hodgkin's disease. Methods and Materials : One hundred and forty-two patients with Hodgkin's disease were treated at the Fox Chase Cancer Center between June 1967 and October 1993. All patients were treated with curative intent with radiation therapy using a mantle field. After exclusion of patienst without available thyroid function tests, <200 days of follow-up, or no radiation to the thyroid, 104 patients were eligible for analysis. Follow-up ranged from 7–170 months (median: 43 months). Sixty-seven patients had a lymphangiogram. Seventy-three patients were treated with radiation alone and 13 with radiation plus chemotherapy. Results : The actuarial 2-, amd 5-year rates of biochemical hypothyroidism for all 104 patients were 18 and 37%, respectively. Forty patients developed hypothyroidism: 9 (23%) at ≤1 year, 18 (45%) at ≤2 years, and 33 (83%) at ≤ 5 years. The actuarial 2-, and 5-year rates of biochemical hypothyroidism for patients who underwent a lymphoangiogram were 23 and 42%, respectively, compared to 9 and 28%, respectively, for patients who received mantle irradiation without a lymphoangiogram ( p = 0.05). The effects of lymphangiogram, total thyroid dose, stage, chemotherapy, dose per fraction, energy, and age were evaluated for all patients by Cox proportional hazards regression analysis. The use of a lymphangiogram ( p = 0.05) was the only variable that significantly influenced hypothyroidism. Conclusions : This paper demonstrates in a multivariate analysis accounting for other potentially important variables the significant effect of lymphangiography and subsequent radiation therapy on the development of hypothyroidism. This information must be balanced with the fact that lymphangiograms remain a useful aid in assessing lymph node involvement, staging patients, and planning treatment fields.