Estimated radiation dose and breast cancer incidence risk of contra-lateral breast for patients with unilateral breast cancer / 中华放射医学与防护杂志

ABSTRACT

Objective To analyze the radiation dose to contra-lateral breasts and estimate the incidence risk of contra-lateral breast cancer for women undergone unilateral breast cancer radiotherapy.Methods The radiation doses of contra-lateral breasts for 49 patients were counted and analyzed in a hospital,and the risk of contra-lateral breast cancer in different age groups that induced by radiotherapy was estimated based on BEIR Ⅶ model combined with the Chinese lifetime table.Results The prescribed doses for the patients were all 50 Gy.The mean dose to contra-lateral breasts ranged from 0.14 Gy to 3.59 Gy,with an average of (1.21 ±0.89) Gy,and the maximum point dose varied from 0.98 Gy to 45.27 Gy,with the average of (17.42 ±13.20) Gy.Both the maximum point dose and the mean dose obviously varied among the patients,and their correlation was significant (R =0.527,P =0.000).Furthermore,no significant differences of the mean dose was found among the ages (P ＞ 0.05).The lifetime attribute risks of contra-lateral breast cancer were estimated to be 2 449,1 857,994,446,173 and 55 for per 100 thousand women corresponding to the ages of 35,40,50,60,70 and 80,respectively.Conclusions In the radiotherapy for unilateral breast cancer,the dose delivered to the contra-lateral breast is about 1 Gy order of magnitude,the risk of contra-lateral breast cancer cannot be ignored for young women.Therefore,the irradiation dose of contra-lateral breasts should be controlled as less as possible in planning the treatment.