THE INFLUENCE OF LYMPHANGIOGRAPHY ON THE DEVELOPMENT OF HYPOTHYROIDISM IN PATIENTS IRRADIATED FOR HODGKINS-DISEASE

Purpose: There is no consensus in the literature regarding the role of lymphangiography in promoting hypothyroidism in individuals with Hodg kin's disease irradiated with a mantle field. We sought to analyze the onset and rate of developing clinical or chemical hypothyroidism as w ell as possible factors related to its development in patients who rec eived irradiation to the thyroid gland during treatment of Hodgkin's d isease. Methods and Materials: One hundred and forty-two patients,vith Hodgkin's disease were treated at the Fox Chase Cancer Center between June 1967 and October 1993. All patients were treated with curative i ntent with radiation therapy using a mantle field. After exclusion of patients without available thyroid function tests, < 200 days of follo w-up, or no radiation to the thyroid, 104 patients were eligible for a nalysis. Follow-up ranged from 7-170 months (median: 43 months). Sixty -seven patients had a lymphangiogram. Seventy-three patients were trea ted with radiation alone and 31 with radiation plus chemotherapy. Resu lts: The actuarial 2-, and 5-year rates of biochemical hypothyroidism for all 104 patients were 18 and 37%, respectively. Forty patients dev eloped hypothyroidism: 9 (23%) at less than or equal to 1 year, 18 (45 %) at less than or equal to 2 years, and 33 (83%) at less than or equa l to 5 years. The actuarial 2-, and 5-year rates of biochemical hypoth yroidism for patients who underwent a lymphangiogram were 23 and 42%, respectively, compared to 9 and 28%, respectively, for patients who re ceived mantle irradiation without a lymphangiogram (p = 0.05). The eff ects of lymphangiogram, total thyroid dose, stage, chemotherapy, dose per fraction, energy, and age were evaluated for all patients by Cox p roportional hazards regression analysis, The use of a lymphangiogram ( p = 0.05) was the only variable that significantly influenced hypothyr oidism. Conclusions: This paper demonstrates in a multivariate analysi s accounting for other potentially important variables the significant effect of lymphangiography and subsequent radiation therapy on the de velopment of hypothyroidism. This information must be balanced with th e fact that lymphangiograms remain a useful aid in assessing lymph nod e involvement, staging patients, and planning treatment fields.